Over 100 years after “London Fog,” is London’s air safe? I just analyzed data on London’s PM2.5 air pollution—tiny particles in the air measuring 2.5 microns and below. In 2018, London averaged 12 micrograms of PM2.5, that’s higher than the World Health Organisation annual limit.

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. And it comes after years of improvement, according to separate World Bank Data.

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!

Monthly Analysis

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.

Caveat: I analysed 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 From London’s PM2.5

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!