Friday 21 August 2020

Day 158 of self-isolation - It's not the heat, it's the humidity

It's not the heat, it's the humidity

Some interesting new research; low humidity leads to more Covid-19 cases. This helps to explain why the sun belt USA is having so many new cases now. Of course, the other causes are still a lack of common sense and too much wishful thinking. Wishing won't make the virus go away.

If it's really hot, then you want to sit indoors with the air conditioning on. When you're indoors, the virus particles don't get dispersed as well as they do when you're outdoors. But aircon also reduces humidity.

The main transmission vector of Covid-19, is the virus particles that you breathe out. They are contained in the water droplets that come out of your mouth and nose when breathing, talking, singing, coughing or (worst) sneezing.

The largest droplets quickly fall to the ground, and can't be breathed in. The smaller droplets stay longer in the air. But the worst is when the droplets evaporate completely, leaving the very microscopic virus particles floating in the air, where they can remain for a long time, and be breathed in by uninfected people.

Air conditioning reduces humidity, and with lower humidity, water evaporates more quickly. So if you're indoors, using aircon, that's the worst possible environment for virus transmission.

It's August now, the hottest time of the year. In the hot states of the USA, people will prefer to be indoors, enjoying the aircon. In the UK, aircon is not common except in cars. Part of the reason for the terrible increase in cases (and deaths) in Florida, Texas, California and other hot states, is the tendency to stay indoors with aircon.

I'm not suggesting that people should stop using aircon, I'm just looking at reasons.

Now let's fast-forward to winter. November to February, is winter in the Northern hemisphere. And it will be cold. People will spend more time indoors, and turn up the heating. That will reduce humidity, and the rest is obvious.

We have a thing called "seasonal flu", so-called because it hits us every winter. It's safe to guess that this winter will be no exception. The seasonal flu is caused by a virus, which is spread in the same ways as Covid-19. Huddling indoors, low humidity leads to more flu and more Covid-19.

I will definitely be getting a vaccination against the seasonal flu, even though I know that it's not 100% protection. It's like walking through nettles; I'd rather be wearing long trousers than none, even though I know that I will still suffer some stings.

I will also be getting a vaccination against Covid-19, if it is approved by the NHS. Because I've done my own research, and I have discovered that there are people in the NHS who really understand this stuff much better than I do, and better than I would even if I spent a couple of years studying virology.

1 comment:

  1. Aircon doesn't necessarily decrease humidity. Despite living in a hot climate I can't take the heat at all, having grown up in a very cold place and never acclimatised. To get some respite I'll often visit air conditioned stores in summer. Sometimes the humidity is lower, sometimes it feels even more clammy than outside. In every case it initially feels cooler once I go inside. However maybe half the time the humidity is higher, in spite of the aircon, and I feel even more sticky than I did outside.

    I'd have thought a serious problem with aircon is what it pumps out, so even if you're not inside you stand a good chance of getting a blast of stale air just walking down the street.