Diary Of An ADI

A Driving Instructor's Blog

The Jen Fog fogging machineRegular readers will know I have referred to JennyChem before, mainly in my article about smearing windscreens. I buy their brand of TFR.

I got an email from them today announcing the launch of their new defogging machine, which claims to do anti-viral sanitising as well as removing tobacco and pet odours. It can be used in cars and for treating small living spaces. It’s called The Jen Fog.

At £145, it’s quite a bit cheaper than other fogging machines, and it comes with 5L of the fogging liquid. Each treatment takes about 20 minutes.

The fogging liquid itself costs £17.50 for 5L. You can even choose between unfragranced, Cherry, Tea Tree and Pine, Strawberry, and Bubblegum scents.

The machine has a 400ml reservoir, and each fill will treat up to 30 cars. So a 5L bottle will be good for up to 375 treatments!

Those numpties looking at buying things to clip on to their air vents should invest a little more – actually, only three times more, because they’re being ripped off with those dinky things – and buy the real McCoy. If anything is going to sanitise the car properly, it’ll be something like this – which is much more cost-effective than some of the prices for ‘refills’ I’ve seen being bandied around social media.

If anyone is interested, these are the datasheets for the FogSan fluid, and it has been tested and confirmed as a viricide.


Product Spec Sheet


Three American MoronsAmerica has a problem. Actually, America has many problems. But with COVID-19, some problems stick out more than others.

Mind you, I say that. But in America right now, pretty much all problems stick out. One of the current ones is in Texas. It seems they have had daily new cases of COVID-19 jump from 2,000 to 6,000 (the article says 5,000, but it is actually 6,000 right now) in a few weeks. Putting that in perspective, Texas has a population which is about a third of the entire UK, yet our maximum number of daily cases has never – apart from one day in April, where I think care homes were added – been much above about 6,000. And the charts indicate it is still accelerating in Texas.

Of course, we had the lockdown. And apart from a worrying number of morons ignoring it, that has brought our daily cases down to around 1,000.

In a similar vein, Texas has seen around 150,000 cases overall. So far. That’s already half of what we’ve seen with three times as many people, and a higher population density.

America has a complicated political structure, whereby state government mainly calls the shots, but this is further complicated by the various amendments to The Constitution, meaning the people pretty much decide whether they follow the Law or not (it’s the ‘Land of the Free’, after all). And if anyone tries to make them, they get their guns out and it gets even more complicated (it’s also the ‘Land of the Stupid’ at the best of times). And all this is completely legal, thanks to that same Constitution.

You could write forever about the American system. But the point I wanted to make was about wearing face masks. It seems that the Texas Governor has urged people to wear masks ‘where it is indicated’. This has proved unpopular – violently so, from what I can gather. And my question in the title is simply illustrated by the photo from the BBC.

See if you can spot the morons in it. Hint: there are three of them, and I’ve numbered them just in case you can’t work it out.


Flip-flops - the most inappropriate driving shoesOriginally published in 2019, so references to ‘recent’ apply to 2019.

With the weather we’ve had recently, there’s a good chance you’ll have had pupils turn up half naked for their lessons ready to sweat all over your seats (one of mine has been bringing a towel to sit on after I ribbed him about wetting the seat). Then, five minutes later, they’re moaning about being too cold because you have the aircon turned on (assuming you’re not a tight-arse who refuses to turn it on to save fuel).

One issue which comes up regularly throughout the year, though, is what they have on their feet.

At the most basic level, a new driver has got to learn how to control the pedals, and especially the clutch. To do that, they’ve got to be able to feel it – which they can’t if they’re wearing big, clunky shoes. Running shoes are probably the worst for this, because they’re specifically designed to absorb shock (and therefore any light touch on the pedals), but any kind of shoe with a platform is going to make clutch control harder. This is especially true if the pupil hasn’t driven before, and even more so if they’re one of the types who is going to have problems in this area anyway.

I had a pupil a few years ago who was one of the jumpy kind. One day I picked her up directly from work, which meant she had ‘forgotten’ her driving shoes. She was wearing platformed Doc Martens – literally, with a four inch chunky heel and bulldozer tread underneath. I abandoned the lesson after less than ten minutes before someone was killed, and drove her home. In a similar vein, I remember once seeing a woman get out of a Mini Cooper wearing massive goth boots with wedge soles that were at least three inches thick (below the knee, she was a ringer for Karloff’s Frankenstein). You cannot drive safely in those. Period.

I always advise pupils to wear flat soled shoes with a thin profile. Anything thick is going to make life difficult, and it drives me crazy when one turns up for their very first lesson in designer running shoes, with the extra thick sole and a concealed wedge heel.

Speaking personally, I absolutely hate it when they want to drive barefoot. My reasoning behind this is that I know from direct experience that you can stub your toe or even cut your foot on the pedals if you hit them in the wrong place at the wrong time, and it bloody hurts. Car manufacturers don’t seem to put much effort into ensuring the undersides of the pedals free from burrs or sharp edges. Furthermore, there is no way most people can brake as hard barefoot as they could in shoes. And if it’s more than half an hour since the car was last valeted, the floor mat will have grit on it, and the last thing you want is to have to execute an emergency stop in your bare feet only to discover something sharp stuck on your sole.

Having said that, I had one pass recently who drove barefoot. I let her do it (after telling her off the first time for trying to stow her shoes in the footwell) after I’d done my usual test in this situation: the Emergency Stop. If they can execute an Emergency Stop barefoot to the standard I expect, then they can drive like that if they want (though I still don’t like it). And she could. However, at the same time she had referred a friend to me who was in the same Halls of Residence, and she couldn’t. One day a few months ago, she came out to a lesson wearing huge furry slip-on slippers (‘why’ was a long story which I’m not sure I fully understand even now). She immediately knew they were not good for driving and asked if she could drive barefoot.

I said that I didn’t mind (because her friend did it), but I was concerned about how well she would be able to operate the brake in bare feet. I asked her to brake firmly while we were stationary and to tell me how it felt. She said it hurt, and she didn’t think she’d be able to brake hard if she needed to on the lesson. Problem solved, and we rescheduled – with the additional light-hearted warning not to come out with the wrong shoes again.

I can think of loads of examples where pupils had previously worn sensible shoes, then come to lessons wearing different though not necessarily inappropriate ones, and had a stinker – just because the shoes are different! Small differences can have a huge effect on some people.

Pupils with larger feet also need to be careful. Anything much above size 9 or 10 doesn’t work well if their shoes have long toe caps, because they’re likely to start catching on the cowling above the pedals. Winkle pickers are a no-no if you have large feet in many normal cars, and since they often have absolutely no grip (just a thin, shiny sole), the risk of the wearer’s foot slipping is also greater.

Very wide- and loose-fitting shoes – Ugg boots spring to mind – are also potentially dangerous, because if you try to slam on the brakes there’s a good chance you’ll make contact with the brake and gas pedals at the same time. And it does happen – it happens sometimes even with small-footed people wearing sensible shoes, so throwing Uggs into the mix is just asking for trouble. The same is true when someone insists on wearing some sort of hobnailed boot two sizes too big as a fashion statement – they’re too bloody wide.

Probably the most dangerous shoes for driving, though, are backless types. Mules, backless sandals, and flip-flops. It’s not necessarily anything to do with the heel thickness – though it can be if they’re platformed – but the fact that they can slip off. I mean, think about it. You can potter about as much as you like in summer wearing flip-flops or mules, but try to run and it’s 50-50 whether they will stay on, and 50-50 whether you end up flat on your face on the pavement or road. They present the same risks in the car if you have to move your foot suddenly to brake – with the additional chance that they will fall under the pedal and prevent you from depressing it fully. They could even get tangled up sufficiently to prevent you being able to brake at all. And don’t dismiss that out of hand – I once had a loop in a shoe lace double bow get itself completely over the clutch pedal (God knows how) so I couldn’t take my foot away or lift it high enough to declutch, and when I slipped the shoe off it swung under the pedal and stopped me declutching fully anyway. Shit happens, as the saying goes.

Strap-on sandals are not so bad, though the open toe arrangement still means you can catch your foot more easily if the sandals are particularly large and oversized (which many are these days).

And it goes without saying that trying to drive in high heels is just plain stupid. The heel messes up how you have to operate the pedals, and you cannot get anything like the same force if you really needed it. Many high heels have shiny soles with little grip, which makes matters even worse.

It isn’t illegal to drive barefoot, nor are any specific types of footwear banned or even mentioned in the Highway Code. The only reference is in Rule 97 (partial quote):

Before setting off. You should ensure that

  • clothing and footwear do not prevent you using the controls in the correct manner

However, DVSA has been quoted separately as follows:

Wear sensible clothing for driving, especially on a long journey. Suitable shoes are particularly important. We also would not recommend driving barefoot because you don’t have the same braking force with bare feet as you do with shoes.

My comments above are based purely on my own experience and knowledge, and they agree completely with this DVSA advice. And so do various other organisations.

I wear flip-flops and never had a problem

This stupid argument makes me angry – especially when it is coming from ADIs.

Everyone knows that if you have a set of expensive crystal glass goblets you shouldn’t drop them. If you do, they’re likely to smash. However, someone somewhere will undoubtedly have dropped one by accident one time, and it will have bounced on the carpet or the arm of a chair, and survived. This does not mean it is OK to drop or mishandle delicate glass goblets. It just means you were bloody lucky.

As I said above, if you try and run in flip-flops or mules, they’re easily likely to come off or send you sprawling (possibly both). The chances of that happening are roughly the same as they are of you getting away with it. If personal injury is one of the possible outcomes, then those odds are not good. If death for you or a passer-by were a possible outcome, they’re catastrophically bad.

There’s no evidence flip-flops are dangerous

You really shouldn’t just say what comes into your head before you’ve fact-checked it. Back in 2016 the insurance company, Sheila’s Wheels, did a survey – and it was of enough people to have statistical significance across the population –  which showed inappropriate footwear was responsible for as many as 1.4 million accidents a year in the UK. Of those surveyed, 60% admitted to driving in ‘inappropriate footwear’. A third said that this involved sandals and flip-flops. And a quarter said they still did it in spite of their previous mishap. About one twentieth to one tenth had actually had an accident as a result.

It doesn’t matter that more people have accidents opening a tin of beans, or taking a sheet of paper out of their printer. Those things have nothing whatsoever to do with driving a car. What matters is that flip-flops are demonstrably dangerous when worn for driving.

I drive in high heels and don’t have a problem

There is no way you can drive as safely in high heels as you can with sensible flat soles. Period. It is a simple scientific fact based on the change to the way you have to apply leverage to the pedals when a high heel is extending and deforming your foot length. Having to brake hard in an emergency situation is going to be a lottery if there is the chance of your four inch heel making contact with the floor before you’ve got the brake on hard enough, or if it snags on the mat.

Remember the example I gave above, of the woman in the goth boots? Three inches of plastic increasing her leg length by 10% and suppressing all feeling of the pedals? Driving in high heels is no different – possibly worse – and anyone who suggests otherwise is a complete idiot, even if they have “always done it”. That’s the risk you’re taking each time you drive in heels.

Pupils will drive in those shoes when they pass

That’s their problem. Your job is to try and educate them in what’s right and what’s stupid while they are with you – not to encourage them in dangerous practices.

I advise all of mine to keep a pair of driving shoes in the car when they pass and not to risk it with heels. Beyond that, it’s up to them.

It’s not against the Law to wear flip-flops

Well, you’d probably still be arguing the toss even if it was. But the fact that it isn’t specifically against the Law doesn’t mean it is the sensible or right thing to do. That it isn’t specifically against the Law means that you doing it is your problem as you struggle with simple common sense. But if you’re encouraging others to do it, then you have become the problem.

But you let people drive barefoot

And I don’t like it. I only give in if they can prove to me that they can do an Emergency Stop properly. As it is, I can count on the fingers of one hand the number who have done it out of many hundreds I have taught. Quite frankly, I wish they would make it illegal to drive barefoot or in inappropriate shoes.

What shoes do your wear?

Deck shoes. I suggest to my male pupils they drive in something similar if they have any issues on lessons. I suggest to the females that ballet pumps with a firm sole are worth a try. It’s surprising how many times I explain – diplomatically – that a driving lesson isn’t a fashion shoot, and people should be comfortable ahead of looking like they’re going to an opera.

Why shouldn’t you put your shoes or bag in the footwell?

If you brake, whatever is down there will move forward. The only place for it to go is under the pedals. So if a kid on a bike rides out in front of you and your bag has moved under the brake or clutch, one of you will be in hospital (or worse) and the other will be up on a careless driving charge (or worse) and about 99% of the way towards becoming an ex-ADI.

Putting your shoes or bag in the footwell isn’t a problem

I have a tidy bag on the back seat of my car for a good reason. On more than one occasion during my driving lifetime, sharp braking has resulted in a bottle or book sliding under the seat and straight under the pedals. The design of the car footwell and the universal laws of physics guarantee that loose objects will end up there if you brake hard. Shit happens.

Storing anything in the footwell is dangerous. I regularly get people wanting to put their shoes, handbags, and even an umbrella (surprisingly common) down there. I simply won’t let them. Because I know from experience how dangerous it is.


COVID SOM imageJust saw this in the news. Driving lessons can recommence from 4 July 2020.

I’m now going to have to let most of my pupils go, since I cannot start immediately as I am still isolating to protect my elderly parents. And it’s too soon, anyway (we can’t socially distance, and far too many new cases of the virus are still occurring daily).

On the plus side, there will be no more idiotic social media posts about ‘when can we go back’ and ‘well, technically, we never had to stop’.

And the official DVSA email has now come through.


The Chillmax AirI wrote this in the summer of 2019. In 2020, I am seeing blanket adverts for the device – or identical devices – some of them priced at frankly silly figures.

Be aware that the device does not work to anything like the levels these ads claim. So be careful. The original article follows.

Early in July 2019, I saw this thing advertised on TV. Then, the same evening, I was shopping in Asda and saw it on display. I am an idiot for things like this, and bought it on impulse so I could test whether it worked or not.

As a chemist, I know full well that if you want to cool a large space down effectively you’re going to need something that uses a special refrigerant. From a practical perspective – where people are going to be in that space, and you need to cool for long periods – that’s going to mean some sort of motor-driven compressor, a closed radiator filled with the refrigerant, a big fan to suck air in and blow it across the radiator, and a wide exhaust pipe through the wall or window to get rid of the “removed heat”. Oh, and probably some sort of collection bucket for the condensed water it takes out, because proper air conditioners dehumidify the air they cool.

The Chillmax Air is much simpler. Anyone who has used a normal fan will know that you only feel “cooler” if you’re sweating. That’s because the fan evaporates your sweat, and that evaporation is accompanied by a small cooling effect – it’s called “evaporative cooling”. Conversely, if the surrounding air is very humid, then no matter how powerful your fan is, you will feel little or no cooling because sweat can only evaporate if the air has capacity to hold additional moisture (I’ll explain that a bit more later).  This same evaporative cooling effect can even be used to freeze water – albeit in very small amounts (and if you’re lucky) – when you force diethyl ether (the stuff they used to use as an anaesthetic) to evaporate quickly. The evaporative cooling effect of different liquids varies greatly, and ether will cool down to a very low temperature if you do it properly. However, ether is both highly flammable and toxic, so apart from demonstrating it in the school lab (where I remember it from, along with the massive headache it gave me), it doesn’t have much practical application these days (though early refrigerators used it, which was spectacularly dangerous).

The Chillmax Air uses the evaporative cooling effect of water, which is much less than ether. The unit consists of a reservoir at the top, which you fill with normal tap water, and this drips down on to a radiator unit which has ten sideways-stacked fibre panels in it through which a fan blows air. The water evaporates from the fibre panels, and the evaporatively cooled air comes out through the front grille. According to the marketing spiel on the TV ad, you’d be forgiven for thinking you’re going to get frostbite if you sit too close. I knew this wasn’t going to happen – but I wanted to know just how effective the Chillmax Air was.

When I set it up and turned it on, the first thing I noticed was that the fan is quite powerful, so you get a good flow of air directed at you – but note that that it’s only about 5″ in diameter, so it can’t beat a proper desk fan for air flow. The next thing I noticed was that the air did seem a little cooler compared with what my desk fan was blowing at me. It also felt different in another way, which I’ll also come to later. But the big question was how much cooler was the exhaust air?

I fired up my trusty data logger and left it in front of my desk fan for 30 minutes for the control data. Then I moved it and suspended it in front of the Chillmax for the same period of time. This is what it recorded (red line is the switch over point).Chillmax Air - temperature recording

The ambient temperature where I ran the test was about 26ºC (it rose by about half a degree because I had entered the room, turned on the TV and my PC, and so on). The Chillmax brought this down by about 2.5ºC (the blip at the end is where it had just run out of water and was starting to warm up again, and I estimate that it might have dropped another degree at most).

So, the Chillmax definitely cools the air that passes through it, albeit by a small amount. Let’s work on the assumption that it would be able to get the same 2.5-3.5ºC drop no matter what the ambient temperature was. It’s for you to decide if that’s worth the investment, but be aware that if the ambient temperature is 38ºC, pulling it down to 35ºC still means it’s damned hot. And also note that since it is so small, the cooling is very localised – it won’t cool a room down.

But there’s a little more to it than that. I mentioned that the exhaust from the Chillmax felt different to what my fan was throwing at me, and not just cooler. If I was going to try and put a word to it, I’d say it felt softer. I already knew what it was, but my data logger shows it in numbers.

This is the data for relative humidity recorded at the same time as the temperature measurement, above (red line is the switch over).Chillmax Air - relative humidity recording

As I’ve already explained, the Chillmax works by evaporating water on fibrous panels by forcing air across them. So where does the water go once it has evaporated? Quite simply, it comes out as a vapour in the cooled air. Well, most of it does. Some of it actually condensed on to my data logger and began to drip during my test. I have since discovered that it also condenses on the front grille and can drip periodically, so you need to be careful if you put it on a shelf with, say, your laptop underneath. This is especially true if you’ve set the grille (which is adjustable) to aim slightly downwards, which you probably would do if it was above eye level. And the fan is quite powerful enough to project the drips forward when they drop.

The ambient humidity in the room where I did the test was about 43%RH. The Chillmax sent that up to nearly 58%RH. The drop at the end is where the water ran out, and it is likely that it would have settled around 60%RH. And that was why the air coming out of it feels softer – it’s more humid than the air being sucked in. When you turn the Chillmax on, you can actually see the vapour in the right light – it’s basically fog.

It’s this raised humidity of the cooled air which really brings into question whether the Chillmax is worth the investment. Most people will know that you can have a hot summer day in the high 20s where it is comfortable and pleasant, and another – perhaps slightly cooler – one which is really sticky and sweaty. That’s because of the humidity, or water vapour in the air.

The amount of water vapour that air can hold varies with the temperature. At very low temperatures, air might only be able to hold a few milligrammes of water per kg, but at higher temperatures this can go up to nearly 100g per kg of air. People generally refer to this as “the humidity”, but the important measurement – and the one people are probably referring to without realising it – is the relative humidity (RH). This is the amount of water in the air expressed as a percentage of the maximum amount it could hold. When the RH hits 100% (more or less the dew point, though there’s a bit more to it than that) at any temperature, then any additional water will condense out immediately. It’s why your car windscreen fogs up in winter as soon as you get inside, because the air is already close to 100%RH and your breath and perspiration immediately causes the dew point to be exceeded. But even below the dew point, you can still get some condensation if there are nuclei which promote it (such as data loggers and the grille on the front of the Chillmax). But the most important detail in all this is that at higher temperatures, high RH is uncomfortable.

The real issue with evaporative cooling comes with changes of temperature when it is already humid. If it is 30ºC outside and 90%RH, dropping the temperature by 3ºC will send the RH up automatically – possibly hitting the dew point there and then. But if you are adding another 500g of water (which is how much the Chillmax holds when you fill it up), and as my data logger showed, you’re pushing the RH up by at least another 10%. On a hot and sticky day, and with the air unable to hold any more moisture, you’re likely to notice dampness when using the Chillmax (I noticed it even in this test). And as I have already mentioned, when the RH is high evaporative cooling from your sweat is less effective, so you would actually feel more uncomfortable even though the air is a few degrees cooler.

Proper air conditioners remove water from the air they cool – so much so that the best ones have humidifiers in them to stop the cooled air from being too dry. In my car, for example, if I have the A/C on the lowest temperature setting my lips start to feel sore because they’re losing moisture, and other people say that it dries their hair out. Proper A/C units use a special refrigerant the same as you get in fridges and freezers, and they cool the inlet air so much that the RH goes beyond the dew point and most of the water condenses out – that’s why you get a pool of water under your car if you stop with the air conditioning turned on in humid weather (or have problems with them icing up if they’re badly drained). It’s also why it is nice and comfy inside an air-conditioned car (apart from your lips) when it’s hot and sweaty outside, even if you have your A/C set at a normal temperature rather than deep-freeze mode most people use. Dry air feels crisp, whereas moist air feels… well, softer. Almost like a sauna if it’s hot enough. The Chillmax does the opposite of normal A/Cs, and adds moisture.

Aesthetically speaking, the Chillmax is a cube – more or less – about 15cm along each side. There are two buttons on the top rear, one which changes the fan speed to one of three settings (or off), with a blue LED for each, and another button that turns the night light on or off. There’s a flap on the top front through which you add the water. The radiator system is a plastic-framed insert which you access by pulling the front grille out. It slots in and out easily. You can’t replace the fibre inserts in the radiator (well, I think you could if you could get hold of them), but you can buy the whole radiator assembly from JML for £15. My only major gripe is the power cable. The jack plug that goes into the Chillmax is quite stubby and doesn’t go into the socket very far, so it is easy to dislodge it. However, the cable itself is quite long, and the  mains plug is a moulded UK type.

JML claims the Chillmax can run for up to 10 hours per fill, but this is undoubtedly on the lowest of the three fan speeds. At top speed, it runs out in less than three hours. To be fair to it, you do still get a noticeable cooling effect on the lowest speed, and since the water lasts longer then, less of it will be getting pumped into the air at any one time, and that might offset what I said about humidity very slightly – but it’s still being pumped out.  JML sells the humidification as a positive without relating it to the comfort relationship between temperature and RH, but note what I said above. If you want to cool down in humid weather, it probably isn’t just the temperature that needs to come down, certainly not a mere 3ºC drop, and definitely not if that means pushing high humidity even higher.

Update #1: I have now tested it in what I considered to be hot and sticky conditions – the kind of weather that means you’re sweating even when sitting still.

Here’s the temperature log (red line again shows the switch over between desk fan and Chillmax.Chillmax - temperature log in hot and sticky conditions

The Chillmax still achieved a similar temperature drop to the initial test. However, the air did not actually feel any cooler blowing on my face. If anything, it was more uncomfortable, though this is a subjective comment. The graph for Relative Humidity below explains why.

Chillmax - RH log in hot and sticky conditionsThe ambient RH was similar to last time, but the Chillmax sent it up to about 70% (a larger jump than in the first test). This is why there was no noticeable improvement in comfort – the small temperature drop was cancelled out by making the air much more humid (i.e. sticky).

You might find the Chillmax useful. It’s quite a smart little device – it’s not a Rolls Royce build, but it’s not badly made for what it is – and not that noisy (but you can hear the fan on the top speed). It certainly cools the air. A little, at any rate, and only close to the unit. Unfortunately, the increase in humidity that goes along with that cooling definitely seems to cancel it out out at higher temperatures – and unfortunately, the humidity affects a much larger room space.

Update #2: I tried it in the latest heatwave (33ºC outside on 23 July) and you can’t feel any cooling effect at all.

Update #3: Right! That’s it! That “latest heatwave” maxed at 38°C indoors on 25 July, and even now – 1am on 26 July – it’s 36°C at 50%RH and I feel The Devil biting my ass. The last thing I want is to send the RH up to 90% using the Chillmax to get the temperature down to only 33°C. God knows how I’m going to sleep tonight. So I have a proper air conditioner arriving tomorrow – watch out for a review of that.

Does it really work?

Well, it does cool the air by a few degrees, but it also sends the humidity up. So if it is already humid and sticky, the cooling effect is completely cancelled out by the extra stickiness. You might get away with that if your windows are open and there’s a through-draught in your house (or personal space), but if it’s also very hot you may not see any benefit at all.

It definitely doesn’t do what you might think it does from those TV ads. It would be fine if it just cooled, but the fact that it also humidifies is the main problem you’re likely to experience.

From my own use of it, I would say that it is a better humidifier than it is a cooler – especially when it is very hot, which is the last thing you want.

Will it cool more if I use ice water?

No. Evaporative coolers are not influenced significantly by the temperature of the water used in them. The temperature of the air that comes out depends on the temperature (and humidity) of the air going in, and the science of evaporation.

Can I use it to cool my PC?

Someone found this article on the search term “jml chillmax air for pc cooling”. If they mean what I think they mean, no, there is absolutely no way you want to be blowing damp air into your PC.

They might have meant powering it from a PC. The mains adapter is rated 5.0V at 1.8A, so assuming the Chillmax does draw 1.8A (and it probably doesn’t, as this is the maximum rating of the adapter) then your PC couldn’t supply that current from a USB port. USB ports are rated at 0.5A or 0.9A depending on the type. Dedicated charging USB ports can handle up to 1.5A, and although that’s a close call (the fan in the Chillmax looks like a computer fan), personally I wouldn’t risk trying to power it from a PC.

Can you get larger versions?

You can certainly get larger evaporative coolers. The working principle is that the larger the surface area of water, and the greater the airflow over that water, then the greater will be the possible drop in temperature at the front end. However, cooling effectiveness is influenced greatly by the RH of the air going in.

If the air is very dry, then a large evaporative cooler might be able to drop inlet air at 30ºC down by as much as 10ºC. However, if the inlet air is very humid, the temperature drop could be as little as 1ºC. In the UK, the realistic temperature drop you could expect on a non-humid day for a large cooler would be around 5-6ºC, but on a sticky day you’d only get about a 3ºC drop.

Suppliers of these devices say that they need good ventilation or extraction, and I would imagine that’s so the humid air can escape. If you’re evaporating more water to get better cooling on larger devices, you’re also producing a lot more water vapour. Be careful if you read any of the reviews – people may have noticed cooling in already cooler conditions, but trust me – if it’s very warm and humid, you aill not notice much effect.

So, does the Chillmax work?

It cools the air by a few degrees. In that sense, it works. But it sends the humidity of that air up considerably, and this cancels out the benefits of the cooling effect in the instances where I tried it. Indeed, when it is already very humid – which is common in UK heatwaves – the device actually makes things worse overall. That’s because comfort isn’t related just to the temperature – the humidity is an important factor. Basically, if it’s already 38°C and humid in your room, dropping the temperature to 33-34°C in a very small area and sending the humidity higher isn’t that much of a benefit. Note that the temperatures I recorded were right in front of the unit – once that cooler air has passed through the warmer air, the benefit once it reaches you is less still – but the humidity still goes up.

Only the air being directed at you is cooler. The device cannot cool down a room. It’s far too small for that.

The increased humidity does produce condensation, so you have to be careful to keep it away from electrical sockets where it might drip on them. The cooler also contains a fair volume of water when full, so you don’t want to knock it over.


Covid-19 on blackboardQuestion: Can I start doing lessons yet?

Answer: There is no Law which directly says you cannot. As in, there is no Law which specifically states ‘driving instructors must not give lessons’. This is probably why your grocer, your hairdresser, your mum, your nan, the police, DVSA, some weirdo you met in the park last night, all your Facebook ‘friends’, and any one of the millions of other people you have repeatedly asked the same question of hasn’t given you the answer that you want. And you’re not going to find the answer by resorting to ‘alternative news’ websites operated by anti-vaxxers and non-qualified ‘medical advisors’.

Obviously, you have a problem with simple logic. But let me try to help.

COVID-19 kills people. Even if it doesn’t kill you, it can kill others. And it does – quite a few of them so far, in fact. Unfortunately, whether or not it does kill you if you catch it can vary in probability from quite unlikely all the way up to virtually guaranteed. The problem is that you don’t know where you are in that range until you try it. And among the higher primates, that is generally regarded as a high-risk strategy, and one to be avoided unless you want to get on the wrong side of Natural Selection.

Now, this is where it is going to get really hard for you to understand. The COVID-19 virus itself is small – much smaller than anything you can imagine. You’d be able to fit more than 30,000 of them across a single French Fry that you’d get with, say, your Happy Meal. They are not physically stopped by anything other than a completely solid and sealed barrier. The simplest way of imagining them is by thinking what happens if either you or your pupil farts on a lesson (or if one of you is particularly odoriferous). Let’s call it the ‘Fart Factor’. Both of you can smell it no matter how much the culprit denies doing it, and neither of you can do anything realistically possible to avoid smelling it. If that fart (or BO) were COVID-19 wafting around, then smelling it means you caught it.

In order to reduce the spread of this fart-like COVID-19, it is important that close person-to-person contact is restricted and – wherever possible – eliminated. That is why we have the ‘2 metre rule’ to keep people away from each other if they meet, and the ‘isolation’ principle otherwise. Two metres is about six times the distance a French Fry travels each time you move it from your tray to your mouth. It is therefore considerably further than the distance between you and your pupils when you’re in your car.

You may have heard talk of reducing this separation distance to 1 metre, or even half a metre. In a car, you are as close as a few centimetres at least some of the time – particularly when a pupil decides to take evasive action over a squirrel they might have seen in a tree 200 metres up the road, and you have to intervene.

Question: I used to clean my car anyway between pupils, so what’s the problem now?

Answer: You used to clean your car because of colds and flu, a build up of gunk from excessive use of hand cream by some pupils of a certain gender on the gear knob, or possibly bad smells left by others with questionable hygiene. At a guess, you’ve probably still had colds and flu in spite of all your cleaning, so it didn’t work. Did it? You might already be able to see where this is heading.

Even that build of gunk on the gear knob is actually there before you can see it. All you did with your precautions was shift the risk – maybe, and only by a little – in your favour. And as we’ve already noted, it wasn’t enough. You still caught colds, and possibly even an interesting skin disorder in some very rare cases. Well, that initially invisible gunk could easily be a coating of COVID-19, and scraping or wiping it off obviously carries an increased risk of exposure above and beyond the fact you were in the car with someone who had it in the first place.

I refer again to the fact that COVID-19 kills people. There’s no vaccine right now, and it is not a cold or flu. If your cleaning precautions fail with COVID-19, keep your fingers crossed there’s no bullet in that particular chamber of the gun you’re now holding to your head. And maybe spare at least a passing thought to all the other people you will now have put in the same situation.

Question: Does an antibacterial sanitizer kill viruses?

Answer: Well, viruses are not actually ‘alive’ in the same way as bacteria are, but the simple answer is yes – most of them. What happens is that a good sanitizer which contains alcohol will ‘denature’ the shell around many viruses and destroy them. This might be less effective for something like Norovirus, which is resistant to alcohol, but it will destroy COVID-19.

However, the whole process relies on actual – and relatively prolonged – contact between the alcohol and the virus. COVID-19 doesn’t turn and run at the mere sight of a bottle of sanitizer. So the $64,000 question is always going to be: did I miss a bit?

I stress that this only applies to alcohol-based sanitizers containing at least 60% alcohol. It does not apply to that hypo-allergenic, vegan, organic citrus-based product with Ylang Ylang and Tea Tree Oil in it in the pretty bottle your Wellbeing coach on Instagram advised you to buy (probably from her).

Question: Does bleach kills viruses?

Answer: As above, the short answer is yes. However, be aware that bleach is also toxic to pretty much everything else, and can cause serious burns if not diluted properly. These burns can lead to permanent nerve damage and also serious eye damage if any gets in those. It also causes breathing problems, especially in people who already have respiratory issues. From a safety perspective you need to be asking if your cleverly devised ‘risk assessment’ has truly considered all the risks – as opposed to having been deliberately constructed just to give you an excuse to start working again –  before sticking bleach in spray bottles and squirting it around inside the car.

Also be aware that bleach can cause an allergic skin reaction in some people even at normal dilutions, the outcome of which can still lead to nerve damage. Skin allergies can develop over time, and don’t always occur immediately. And the long-term effects of bleach on the plastics and fabrics in your car are unlikely to be of the positive variety. Bleach at any concentration should not be used as a hand-sanitizer.

You ought to consider all this before concluding that Domestos is cheaper than alcohol-based hand sanitizer.

Question: Do face masks work?

Answer: Viruses are not stopped by normal face masks (aka surgical masks’). All these do is catch some/most of the larger droplets of moisture (containing the virus), and this reduces the number of virus ‘spores’ being circulated beyond the mask. It doesn’t eliminate them. And of course, until they become inactive, the mask is still contaminated with them when you fling it on to the back seat and it dries out, while you put a clean one on

All you have to do is try one while you’re wearing glasses and see how easily they steam up. Well, that ‘steam’ could easily contain viruses, and that’s where the Fart Factor comes into play again (including what that dirty one on the back seat is doing while you continue your lesson). Also consider that the ‘steam’ is coming from the other person in the car too, and if your ‘steam’ can get out, theirs can get in through the same channels. And vice versa.

You need proper respirator masks to give any serious protection against viruses. At least an FFP2 or FFP3. These are single use, like surgical masks, but create a tight seal around the nose and mouth, and have a small enough pore size to stop viruses. They’re difficult to breathe through as a result, and the tight fit makes them uncomfortable – especially worn over long periods. And they cost about £3 each – if you can get them. In theory, you can wear one for up to 3 hours, but if you take it off at any point you ought to use a new one.

Proper respirators can cause facial skin damage if worn repeatedly and/or for long periods.

Question: Does having the windows open reduce the risk?

Answer: If you’ve ever driven at moderate speed with the windows fully open, and had empty plastic bags on the back seat for any reason, you will probably have experienced what can happen. The bags can get pulled into a vortex – a bit like a tornado – inside the car, spin a round for a while, then get sucked out of the windows. Let’s call this one the ‘Vortex Factor’.

If you’re desperate to return to work, you might be tempted to conclude from your ‘risk assessment’ that yes, having the windows open reduces the risk. But just ask yourself what happens while that vortex – this time containing invisible COVID-19 spores stirred up from old masks and things – is still inside the car, and before it heads for the windows. And think further about what happens when the vortex is less as a result of the windows being only slightly open, so it never bothers with a full exit. Think Fart Factor.

The last week has seen many torrential downpours around the country, and these look set to continue for the next week at least. It’s what often happens in summer in the UK. If it rains, and the car windows are open even a little, you get wet. If this concept is still too difficult to understand, I will write a separate article on why rain is wet, and why it gets in through open windows.

The short answer is that having the windows open could actually increase the risk in one way, even if it could potentially reduce it in another. At best, the two just cancel each other out – but I would think the increased risk carries more weight than the reduction. And you’ll get wet if it rains.

Question: Do those wing-dang-doodles you plug into the USB socket work?

Answer: People have started looking at fitting ‘air purifiers’ in their cars. Such a device would have to process all the air before it was passed on to you to breathe to be of any use. And I mean all the air. You see, air is an ideal Fart Factor medium, and it is very difficult to keep one bucket of air containing a fart away from other (clean) buckets of air, unless the buckets you use are completely sealed – much like in a balloon. In order to implement this for a human, said human would need to be in a completely sealed suit, and have the purified air fed to them inside the suit via hoses from the processing unit. One bucket of air would be good for two, maybe three deep breaths, and this is why scuba divers have tanks of compressed air with them underwater, since two or three breaths tends to limit how much exploration of the ocean depths is possible. To filter air on demand – and especially to the level of filtration needed to remove viral particles – means the processing unit would need to be at least the size of a large suitcase. And you’d still need to be inside a sealed suit to use it, otherwise it would be pointless.

If you can guarantee that each and every COVID-19 ‘spore’ passes through something which ‘kills’ it before it get’s anywhere near your nose, mouth, or bare skin, any device which claimed to do this would be an ideal investment. However, something the size of a mobile phone clipped on the dashboard (or kettle-sized under the seats) wafting Tea Tree Oil and Ylang Ylang into the car is unlikely (as in ‘it can’t’) to be capable of doing so. And it doesn’t matter what they put in it – essential oils, alcohol, bleach, Plutonium – it simply cannot work.

So thanks to the Vortex Factor, you’ll be breathing plenty of the ‘nasty’ air at the same time. Yes, such a gizmo may well ‘kill’ the spores if any pass through it – though given that it probably costs about as much as a handful of Happy Meals, that is far from guaranteed (as in ‘it isn’t’) – but I honestly can’t see them being fitted into hospitals and other settings anytime soon.

Question: Do Perspex dividing screens work?

Answer: If someone coughs directly at you, or tries to spit at you, yes. They stop them coughing or spitting directly in your face. However, due to the Fart Factor and the Vortex Factor, they cannot stop viral ‘spores’ circulating around the car. So no, they do not eliminate or ‘stop’ the virus.

Some insurance companies will not allow them, although some apparently do. The issue is maintaining control of the car. You see normal driving instructors – as opposed to the ones with enlarged frontal lobes who can apparently control the car, the pupil, and the overall lesson just by a few pulses of their lobes – occasionally need to take physical control away from the pupil to prevent harm coming to the vehicle and other road users. It is hard to do that when there’s a bloody big plastic screen in the way.

The solution to this problem for some seems to be that you simply have a big hole cut in the Perspex so that you can reach the steering wheel, thus allowing greater influence from the Fart Factor and the Vortex factor, and completely negating the original purpose.

Then there is the issue of ‘sanitizing’. Your fancy new screen has now given you a new surface area in the car of between 3-6 square metres. It has also made some of the existing surfaces (i.e. between the seats) even more difficult to access than usual. And it has introduced a lot of very fiddly nooks and crannies that were not there before that you will need a Q-tip or toothpick to get to.

Perspex (or acrylic) can be attacked by bleach, and the surface becomes ‘crazed’ (small cracks, which make it go cloudy). So your Domestos idea will need to be shelved, and you’ll be using a ton of alcohol sanitizer instead. Hand sanitizer contains other ingredients that prevent your hands drying out, and these may also attack Perspex. If nothing else, they’ll leave an oily film behind, leading to more cleaning.

Finally, and even if your insurance has cleared it, there is the ‘what if?’ question. As in, what happens if you do have an accident and your arm is through the hole at the time (which it likely will be under such circumstances)? The jolt of an impact alone is likely to snap it like a twig as your body weight is thrown around and your arm is levered against the Perspex. And if compression of the vehicle occurs, the Perspex will snap and turn into a giant pair of scissors and a variety of very sharp daggers – with your arm right in the middle of it all.

It’s a hell of a risk over something which doesn’t bloody work in the first place – unless you get a lot of people who spit at you, or you’ve allowed someone in the car even though they have a chronic cough.


I just saw this video posted by Jeremy Vine on his Twitter feed. For anyone who doesn’t know, Vine is the cycling equivalent of a Born Again Christian. He never gives up in his crusades. And they are legion.

There are two incidents in the video. The first – which he circles – is where a car pulls out into the cycle lane, forcing him to have to deviate slightly from the cycle lane (ironically, his Twitter feed shows another video where he’s in and out of the cycle lane avoiding puddles). That’s wrong on the part of the driver.

But in the second case, HE is in the wrong. The Highway Code says:

Rules for cyclists (59 to 82)

Rule 72

On the left. When approaching a junction on the left, watch out for vehicles turning in front of you, out of or into the side road. Just before you turn, check for undertaking cyclists or motorcyclists. Do not ride on the inside of vehicles signalling or slowing down to turn left.

Vine was in complete contravention of this. The car was in front of him all the time. It indicated well before turning, so Vine – as the big nuts, all-seeing, all-knowing űber-cyclist he believes he is – would have known exactly what it was intending to do. Instead, he pumps on without slowing even a fraction and attempts to undertake it. The only possible alternative for the car driver, had she known he was trying this, would have been to slam her brakes on to let Vine pass – with the risk of someone slamming into the back of her. She should not have been put in that situation by someone blatantly disregarding the Highway Code as it applies to them.

Vine cleverly captions her comment on the video: ‘Oh my God. I didn’t see you at all’. I know what my response would have been, and part of it would have rhymed with ‘clucking bat’.

It’s really coming to something when cyclists who do things like this believe they are somehow in the right. And they seem prepared to put their lives at risk trying to exercise it.


I received an email alert from DVSA today (as should most other instructors have done). Basically – and except for key workers – all tests are off until further notice. The essential part is reproduced here:

Driving instruction and driving tests

Other than emergency training and tests for critical workers, driving instruction and driving tests have not yet been able to restart because the risk of transmission of the virus in vehicles is higher.

In his statement on 10 June, the Prime Minister reiterated that the government will remain cautious and measure the effect of the changes it makes. The Prime Minister explained this means moving slower than we’d have liked in some areas.

Driving instruction and tests will only restart when the government is confident that the assessment of risk warrants it, subject to the 5 tests and further detailed scientific advice.

In the meantime, I want to re-emphasise that you should continue to limit driving lessons to critical workers who are preparing for an emergency driving test.

Once again, I would like to thank those of you who have been able to offer driving lessons to critical workers during these unprecedented times.

We will, of course, share more information with you as soon as it’s available – including the dates that driving instruction and driving tests can restart.

Any change to this is wholly dependent on what COVID-19 does next, and what the government decides as a result. That is unlikely to occur before July at the earliest, and I have texted all my pupils this afternoon indicating that we are unlikely to be doing lessons before August at the earliest.

One of my pupils has already received a cancellation email – and it is a cancellation, not a rescheduled date. That ought to be telling you something.

I have highlighted in bold the part DVSA emphasises in its email. For anyone too stupid to understand it, it says you should only be giving lessons to key workers who are preparing for a driving test.

I am awaiting the usual clowns arguing ‘yes, but it says should, not MUST’ (a reference to the terminology used in the Highway Code, where the difference is between advice or Law). I’d point out to these idiots that even going against advice can often lead you towards the hard legal aspects. Quite easily. In this case, by working when you shouldn’t you’re probably making the delay for everybody else longer, as you help COVID-19 spread.

Just remember. Apart from the money-grabbing aspect, there is absolutely no point teaching people at the moment if they cannot book a test. Try as you might to sound philanthropical about it, you’re doing it for you, not them. And it shines through like a beacon. Even if you do go ahead and work – and it cracks me up to see all these people who’ve been saying we can, and they’re going to start again ‘on Monday’ every week without fail (but haven’t) – what will you do once your pupils reach test standard? It’s likely there’ll be no tests until September – maybe longer if the shit hits the fan again, which you working is likely to help happen – and that’s three months away. By then you’ll possibly have blown your chances with SEISS (Part 2) and run out of people to teach. And that’s even assuming you can run a full diary right now (with most pupils not being as clueless as you and staying safe), and having to sanitise the car with a gallon of sanitizer every hour.


COVID School of MotoringThey get, worse. They really do. Why do people who are usually unable to even do their own accounts insist on reading into things, and then create concerns among others?

A few weeks ago, it was announced that the SEISS scheme would be paid for a 2nd and final time, and you’ll be able to apply in August. Bear in mind that SEISS is not something created specifically for driving instructors – it is for self-employed people. It may come as a surprise, but there are more self-employed people out there than there are driving instructors. A lot more.

The Government website states:

This scheme is being extended, and you’ll be able to claim a second and final grant in August 2020.

We will work out your eligibility the same way as the first grant. If you make a claim for the second grant you will have to confirm your business has been adversely affected on or after 14 July 2020.

This grant will be a taxable grant worth 70% of your average monthly trading profits, paid out in a single instalment covering a further 3 months’ worth of profits, and capped at £6,570 in total.

You can claim for the second and final grant even if you did not make a claim for the first grant.

It is the part about ‘on or after 14 July’ which has steamed up a few pairs of bifocals. Apparently, if you twist it around enough, you can convince yourself that they aren’t paying you for June.

Look, it’s really simple. In August you will be able to claim 70% of your average monthly business profit (not 80%, like last time), for a further three months of missed work. It’s up to you whether you include June in that, but it’s still three months – it says so in black and white.

The part about having to confirm your business is affected is fairly obvious – because of the aforementioned belief that SEISS is only for instructors. That condition was in there from the moment they announced it on 31 May, and is more relevant to the vast majority of self-employed people who could be working fairly normally by that time.

If you’re one of those instructors who has been itching to get back – and even if you’re one of the ones who has spent the time since March spamming every message board going telling people ‘technically, we can work’, even though you haven’t – if you are working before 14 July then it’s your problem if HMRC decides you are not affected and therefore not eligible. Just as it would be for me.

The problem here is that it is obvious to anyone with any sense that driving instructors should not be working right now. Even if you manage to cram all the good things you’ve read into a toothpaste tube and squeeze them out into a convoluted sentence that leads you to conclude you technically can work, you shouldn’t be. Even if you dunk your car in a bath of sanitizer between lessons you shouldn’t be. And even if you conduct lessons wearing a deep-sea diving suit you shouldn’t be. Because the virus is still there, at quite a high level, and you will be shut in a tin box with strangers less than half a metre away from you for hours at a time. The only thing you’re thinking of is money – which explains why some people are prepared both to go back to work as soon as they can and try to claim SEISS on top.

I know full well I will not be working on 14 July. Even if I technically can.

They’re going to take it off you again

No. They. Aren’t.

Jesus, how thick do you need to be? If you were eligible in the first place – by not working at all, and not getting a mountain of income from stocks and shares, or a pension – the first SEISS is yours, as long as you didn’t lie to them. If you did lie, it serves you right if you have to pay it back.

The criterion was that if more than 50% of your income over the last three years was from self-employment, you were eligible for the SEISS. That’s how it was for me – initially, 100% of my income was from self-employment over the last three years, and half way through it switched to 70% self-employment and 30% private pension. My PAYE account, along with my self-assessment, shows HMRC clearly what my income was. I had purposely dialled back on work because of my pension – with hindsight, and for purely financial reasons, I wish I hadn’t. But that’s irrelevant. Even if I’d always had that pension, I’d still have been eligible.

In August, and unless I am am working normally, I will be eligible again. I may have to prove that, but it would be no issue at all doing so.

The only way you’d need to pay anything back is if it turned out you’d been working normally throughout the period. If they caught up with you on that, it’s up to you to sort it out. You shouldn’t have been working, and if you were and still claimed, you only have yourself to blame.


Sweet - Steve Priest on the leftAnother legend from my childhood gone. Sweet were one of the glam rock pioneers in the early 70s, and one of the bands I grew up with.

The 70s was easily the best for music.

Steve Priest – one of the founding members – was the one who wore make-up and big ear-rings. RIP, Steve.

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