Monday, October 11, 2010
I didn't need any air quality meter to tell me the pollution was bad-- you could just see, smell and (I might be imagining...) taste it, but this is what the air quality index for Beijing said yesterday around the time that Simon was to play soccer:
10-10-2010; 11:00; PM2.5; 408.0; 439; Hazardous // Ozone; no data
about 24 hours ago via BeijingAir AQI Tweet (Source: http://www.twitter.com/beijingair)
Translated, this means that on Sunday morning 10 October at 11am, the concentration of fine particular matter (PM2.5, which are the tiniest particles, smaller than 2.5 micrometer across, thus smaller than a human hair and beyond what you can see with the naked eye) was 408.0 ug/m3 (micrograms per cubic meter air), which translated into an Air Quality Index of 439. (And for Ozone there was no data).
Well, an Air Quality Index of 439 is pretty much off the charts if you look at this EPA overview of the Index:
Source: Air Quality Index (AQI): A Guide to Air Quality and Your Health.
All Friday and throughout the weekend we were in the "Hazardous" category.
In a nutshell, these extremely small particles in the air are a mixture of tiny solids and liquid droplets, all of different sizes and origin. They are (in part) created when fuel, like coal, oil, diesel, or wood, are burned, for example in a power plant or when we are driving a car. If they are not trapped in a filter at the time that they are created, the particles get up in the air, where -- if there are a lot of them and wind and rain do not move them out, they simply sit and form a dusty blanket.
Now, the Air Index above focuses on the PM2.5 particles, the particles smaller than 2.5 micrometer across. This is because the smaller the particles are, the larger their effect on your health, as it is these tiny particles that make it past your nose and throat, all the way into your lungs. (The larger particles, larger than 10 micrometer across, just irritate your nose, throat and eyes, which is annoying, but not nearly as bad as getting a lung disease.)
(If you're fascinated by particulate matter now, you can continue reading on this U.S. EPA website. Dutchies may want to check out this page on fijnstof.)
Luckily for us, there was a heavy rain last night, so today the sky is blue (as the particles are out of the sky and now moving on to ground and surface water). The air quality index reads:
10-11-2010; 11:00; PM2.5; 5.0; 16; Good // Ozone; no data
3 minutes ago via BeijingAir AQI Tweet