How Effective is the Hand Sanitiser in Your Car?

Soap and water is hands down the most effective and thorough way to clean your hands. Despite this, many of us still rely on hand sanitisers when soap and water is not available and simply because (let’s face it) it is more convenient.

Hence why many of us carry travel-sized sanitisers in our purses, bags and an even bigger bottle in our cars – in case we run out, forget, etcetera. Knowing us Malaysians, sure thinkbuy big bottle also more value for money mah.” “Satu duduk kat rumah, lepas tu satu lagi buat spare dalam kereta.”

But the truth is, you shouldn’t leave your sanitisers in the car and here are some of the reasons why:

OH! I know… my car will explode right?

While it is possible, it is highly unlikely and if it does happen it is probably not due to the heat in the car. This is following the viral Facebook post from a fire department in Wisconsin claiming that a hand sanitiser exploded after it was left in a hot car.

Experts later slammed the viral post because it is very unlikely for a hand sanitiser to combust in a hot car. First of all the most common alcohol found in hand sanitisers is ethanol. It is the same type of alcohol that is found in wine, beer, and liquors except hand sanitisers have a much higher concentration (roughly about 70%, which is the requirement needed to combat coronavirus).

Yalo, so because of the alcohol, sure explode lah kan?

Not really, because according to the National Fire Protection Association (NFPA) in the US, a spontaneous combustion involves self-heating. And since hand sanitisers is not subject to self-heating, therefore the interior of your car will need to reach temperatures of approximately 370 degrees for it to spontaneously combust. 

Abuden?! So can keep hand sanitisers in the car lah!

You can, but only for a short while and not for extended periods of time. The reasoning behind this is because Ethanol has a significantly lower boiling point than water. This simply means that it heats up faster and evaporates much faster at any temperature compared to water.

So the MAIN worry here is the evaporation of the alcohol in hand sanitisers which in turn would make them less effective. After all, we are all trying to keep everyone safe and prevent them from contracting germs and viruses. 

Experts suggests avoiding excessive heat that is above 40 degrees celsius and if you really need to leave your hand sanitiser in the car then do so temporarily. From the table above, you can see just how quickly the interior temperature of the car increases with time. Even with the bottle firmly closed, there is still the chance of alcohol evaporating. Let’s not forget that when the concentration of the alcohol is compromised, so does its germ-killing ability.

Another thing to take into consideration is how UV light reacts with hydrogen peroxide by converting it into water. Hydrogen peroxide is the other active ingredient found in sanitisers. So what happens if both active ingredients for combating germs are lacking from your hand sanitiser? Will it still be as effective? Thus, it is recommended that hand sanitisers be stored away from direct sunlight and not left in warm enironments. If you must, store it away in the glove compartment or the car’s middle compartment and remember to take it out when you get out of your car.

Habis? So should I throw away the sanitiser that has been sitting in my car?

Now before you go Marie Kondo your car and get rid of all hand sanitisers that no longer spark joy, there is a simple trick to check if your hand sanitizer is still effective. You can check my examining the viscosity / texture of the sanitizer in the bottle. It should be somewhat runny and easy to swivel around in the bottle easily. When applied to your hands, it should dry pretty quickly. 

If the texture of your hand sanitiser has gotten thicker and it doesn’t seem to be evaporating as quickly as it used to, then it is probably best to dump it. Why rasa sayang, if it is not going to keep you and your loved one safe from the virus? For the same reasons, all hand sanitiser come with an expiration date. So please do not hesitate to discard them if they are no longer effective and make sure to check that they are not expired – especially with school rolling around the corner. 

Don’t say tidak apa lah. When in doubt, just replace the bottle. In this situation, it is better to feel assured that you and your loved ones are safe rather than fuss over wastage.

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