PM2.5 stands for Particulate Matter less than 2.5 micrometers in size. They are small enough that they penetrate deeply into the lungs and get stuck there. According to the World Health Organization, they are now recognized as causing “respiratory and cardiovascular morbidity, such as aggravation of asthma, respiratory symptoms and an increase in hospital admissions; mortality from cardiovascular and respiratory diseases and from lung cancer.”
Now new data from the Greater London Authority show that everybody in the entire Greater London area is breathing more PM2.5 than is recommended by the World Health Organization of 10 micrograms per cubic meter, although even the WHO says there is no evidence that there is any safe level.
Greater London Council/Public Domain
The Mayor of London, Sadiq Khan, is quoted in the Guardian:
It’s sickening to know that not a single area of London meets World Health Organisation health standards, but even worse than that, nearly 95% of the capital is exceeding these guidelines by at least 50%….We should be ashamed that our young people – the next generation of Londoners – are being exposed to these tiny particles of toxic dust that are seriously damaging their lungs and shortening their life expectancy.
The biggest source of PM2.5 in London is transportation, but surprisingly, the biggest source isn’t diesel exhaust; it is, according to the report, tire and brake wear. So for everyone who thinks electric cars will save us, think again.
As the number of zero emissions vehicles increases and exhaust emissions fall, the proportion of transport emissions that come from road, tyre and brake wear increases. By 2030, an estimated 90 percent of PM emissions from road transport will be from tyre and brake wear. … the most effective reduction of tyre and brake emissions is to reduce the vehicle kilometres being driven. This will be one of the many co-benefits of the Mayor’s Healthy Streets approach and the huge investments being made in walking, cycling and public transport.
Lloyd Alter/ morning in Tienanmen Square/CC BY 2.0
London air is bad, but many cities have unsafe PM2.5 levels; New York City hit 60 recently, and Toronto downtown hit 63. Beijing maxed out at 132, which is relatively good for that city. The worldwide background average is 22. (Check your city here).
The WHO notes that PM2.5 were thought of as a respiratory problem, but more and more, it is being recognized as a cause of a wide range of cardiovascular diseases and a major cause of death. It contributes to 3.3 million deaths per year.
But the main sources of PM2.5 are coal and cars, so it’s not going away.