London’s poor rating for sanitation (67th) by the recently released Mercer Quality of Living Rankings due to “persistent air pollution and traffic congestion” prompted London Cleaning System to investigate the issue of air pollution in the UK capital.
Looking at official data on air pollution in London, the company researchers observed a significant improvement over the recent years and that the majority of the most harmful air pollutants are not “at levels that affect human health”. But the researchers also found that some air pollutants remain a major concern. These include nitrogen dioxide (NO2) which, according to a King’s College London study claimed 5,900 lives in the UK capital in 2010.
The official figures show that since 2010, NO2 concentrations in London dropped significantly but despite that, the EU yearly NO2 maximum was exceeded as early as end of January 2018. Further analysis of London’s NO2 levels from January 2010 to January 2018 also showed a dramatic difference in monthly average concentrations between roadside and background monitoring sites. Roadside sites had continuously higher readings although these didn’t exceed the “low” index level even once from January 2010 to January 2018.
London Cleaning System also noticed that mean daily NO2 concentrations show a very predictable pattern. The NO2 levels in the UK capital begin to rise just before the morning and afternoon rush hours, and peak around 8 to 9 am and 5 to 6 pm. Just like the monthly averages, mean daily concentrations are higher at roadside during all times of the day.
Compared to January 2016, the NO2 mean levels in January 2018 dropped considerably at both roadside and background, reaching a maximum of 60.3 ug/m3 and 50.9 ug/m3, respectively. This is a decrease of nearly 20% at roadside and nearly 17% in background.
The results of NO2 readings during morning and afternoon hours are important for two reasons. First, they provide strong evidence that traffic is the main source of NO2 pollution in the UK capital. And second, they mean that Londoners living at roadside, especially those living at the most congested roads, are at increased risk of health problems associated with exposure to high NO2 levels. To reduce these risks, it may help to keep the windows closed and avoid outdoor activities during morning and afternoon rush hours.