When spring finally came, it came in HOT!
Temperatures have been into the 30s for most of the last week, and with the still, warm air over the city, the air quality has been noticeably decreasing. But what we’re seeing (or not seeing, because it’s so polluted) at the moment is only classed as “Moderate” on the AQI (Air Quality Index (low numbers are better numbers)) scale:
But look at that: today’s allegedly “Moderate” levels have nothing on tomorrow, where – in the early afternoon – we’re looking at “Very Unhealthy” air quality, before returning to something altogether (well, slightly) more satisfactory on Wednesday and Thursday.
Here’s the AQI scale for reference:
And you’ll note immediately that we run up 3 steps to the penultimate level of nastiness in the next 24 hours. That’s mainly due to high counts for PM2.5 and low level ozone:
PM2.5, (also written PM2.5) are tiny particles of dust or soot – especially prevalent in vehicle exhaust fumes – and which are contributing to the murky, hazy atmosphere over the city at the moment.
Then – and bear with me here – add in those high levels of low level ozone…
Yes, I know it’s a bit confusing: high levels of high level ozone are good – thanks for using your roll-on deodorant back in the 1980s and 90s – but we really only want the ozone about 20 or 25km up there, and not at ground level:
Ground-level ozone or the “bad” ozone that forms closer to the Earth in the air we breathe. This ozone is not usually emitted directly, but rather forms from chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in sunlight.
These pollutants can have acute effects on people who suffer with asthma or other respiratory diseases. Especially at these hugely elevated levels. It’s not called “Very Unhealthy” just for shits and giggles (neither of which are symptoms, by the way).
Longer term effects can include cardio-vascular problems and issues in pregnancy, but we’re fortunate in Cape Town that while quite ugly, these are fairly rare levels for this little corner of Africa.
A small cold front passing over or near to the Cape on Wednesday will see a lot of this nastiness blown out into the South Atlantic where it can dissipate and harm the wildlife instead of us important humans.
But in the meantime, if you are sensitive to pollution and/or you do suffer from asthma or a respiratory illness, you might want to take steps to protect yourself from what promises to be a rather unpleasant day tomorrow.
Stay safe.
