I just analyzed data on London’s PM2.5 pollution and found that it averaged 12 micrograms in 2018.
What Does That Mean?
Based on this data from the King’s College London, London’s air quality is slightly above the WHO annual limit. That limit is important because research shows that even levels around 10 micrograms affect our health.
However, 12 micrograms is already pretty good; it’s just within the ‘Healthy’ range for the US air quality index. London’s PM2.5 is lower than other major cities like Paris and Berlin, although there are safer major cities, such as Montreal.
But compared to the cities around the world that are famous for pollution, like Delhi or Beijing, London isn’t even close!
However, one problem with the data above is that it averages over the entire year. When we do a month-by-month analysis, we can see that London’s air is in the ‘Moderate’ range about half the time.
Bottom line: London’s PM2.5 is not the worst in the world but averages slightly above the WHO annual limit.
Caveat: I analyzed PM2.5 data. This covers particles in the air, but it doesn’t cover gas pollutants like NO2. That’s important for London because studies have found unhealthy NO2 levels in London and around England.
How to Protect Yourself
Despite London’s relatively good air quality, measures can still be taken to protect against air pollution. Studies have found that wearing a mask outdoors during bad air pollution prevents harmful effects on blood pressure and heart rate variability. Even at very low levels of air pollution, a study in the US found that using air purifiers to reduce indoor PM2.5 from 11 micrograms to 7 micrograms significantly improved blood pressure.
Breathe safe, London!
Kang Wei is a chemical engineer from the National University of Singapore. He’s currently working on R&D and engineering at Smart Air.