The importance of PM2.5 air pollution has finally been recognised with the Department of Environment, Food and Rural Affair (Defra) launching its new Daily Air Quality Index (DAQI) earlier this year. Previously, the index had not changed for 12 years. Defra took advice from the Committee on the Medical Effects of Air Pollution when redesigning the index.
There are coloured index bands for each of the key pollutants, namely:
- Nitrogen dioxide
- Sulphur dioxide
- PM10s (particles of size 10 microns or less)
- PM2.5s (particles of size 2.5 microns or less).
Levels of pollution on the air quality index are classed from 1-10, depending on the level measured. Levels 1-3 are classed 'low', 4-6 'moderate', 7-9 'high' and 10 'very high'. Each air quality index band is linked to advice for both healthy people and those suffering with asthma symptoms and other lung problems, or heart problems.
This strikes me as being a good way of displaying the information that is measured, day in day out, by the UK's network of air pollution monitoring stations.
On the day of writing this (a wet mid-February Saturday) I checked out the air quality index for several sites in London and was relieved to find levels of all five pollutants were relatively low. You get information for your area by clicking on Defra's interactive map. I suggest you check back often – not just if you suffer with asthma but just in the interests of being a concerned and informed citizen! You then have all the facts at your disposal to lobby against any local pollution sources, such as traffic congestion.
As far as PM2.5s are concerned, it looks as if the UK and Beijing are on the same page. The US Embassy in Beijing has been broadcasting PM2.5 data via Twitter for some time now and has, seemingly, embarrassed the Beijing government into stating that it, too, will publish official figures on PM2.5 pollution.
PM2.5 air pollution penetrates deep into the lungs and may even enter the bloodstream. Exposure causes coughing, wheezing, decreased lung function and is thought to be an asthma cause. It has also been linked to premature death among those with existing lung and heart disease.
Just for comparison, I checked PM2.5 levels in London and Beijing on the same mid-February day. In London, the highest level (Marylebone Road – one of London's busiest roads) of PM2.5 was 25 micrograms per cubic meter, while in Beijing it was over four times higher at a level of 105. Clearly the Chinese capital has a long way to go in cleaning up its pollution levels. And London cannot afford to be complacent either – a low PM2.5 reading on that single day, to be sure, but how will levels change in the coming months.