Cities Outlook 2020


This report from the UK think tank Centre for Cities takes an in-depth look at air pollution.

Air pollution is an urban problem

Centre for Cities finds that air quality tends to be worse in urban areas. The report estimates that just one pollutant, PM2.5, is the cause of more than one in 19 deaths in the UK’s largest cities and towns — even though the UK currently meets legal limits. Research also found that 95 per cent of the monitored roads in the UK that are breaching the legal limits for NO2 are in the UK’s largest cities and towns.

Which cities are worst affected by poor air quality?

Air quality is worse in some cities compared to others. There is a clear South / North divide to the problem. Across multiple indicators, cities in the South of England do worse than others. For example, in 2018 there were 62 days when pollution in Bournemouth rose to levels affecting those with health conditions like asthma (according to the Met Office’s Daily Air Quality Index); whereas in Belfast there were eight. The proportion of deaths related to the PM2.5 pollutant is highest in cities in southeastern England such as Slough, Luton and London — where an estimated one in 16 people dies from exposure. Cities in Scotland and northern England see the smallest proportion of PM2.5-related deaths. Aberdeen is the city with the lowest proportion, at one in 33.

What are the sources of air pollution?

The sources of emissions vary from place to place but transport and the burning of wood and coal are between them the biggest contributors. Transport is the main source of NO2 emissions but is not the only one. At a national level, road transport accounts for 34 per cent of all NO2 emissions, and this rises to 42 per cent in cities — it represents the biggest source of local NO2 in 54 cities. But transport plays a smaller role in PM2.5 emissions, accounting for 12 per cent of these emissions at a national level, with similar levels in UK cities. Instead, it is domestic combustion (for example, through coal or wood fires) that is the biggest contributor. In cities, 50 per cent of PM2.5 levels can be explained by domestic wood and coal burning. But there is also variation within urban areas. While road transport’s contribution is much higher in city centres, in suburbs more than half of PM2.5 emissions come from domestic and commercial combustion. This shows that in tackling air pollution, different approaches will be required even within a city.

How does poor air quality affect our health?

Air pollution kills thousands of people each year, and affects the health of many more. Although local data on the number of people whose health is affected by poor air quality is limited — what can be estimated are the deaths attributable to one pollutant, PM2.5, in cities across the UK. This one pollutant is estimated to have caused just over 14,400 deaths of those aged 25 or older in UK cities in 2017. Looking in this way at the proportion of local deaths that can be attributed to long-term exposure to PM2.5 reveals that London, Slough, Chatham and Luton top the list with one in 16 deaths. This is contrast to Dundee and Aberdeen, where one in 33 deaths is related to exposure. These deaths occur in spite of the UK meeting current legal limits for PM2.5 in the air.

What do cities and the Government need to do to clean up the air we breathe?

Laudable environmental concerns in relation to climate change need to be mirrored in action on the linked issue of air pollution. Politically, it is difficult given the strength of the motoring and other lobbies but it is by no means impossible as London has shown. After all, this is an issue that is affecting the health of people living and working in cities, that increases the number of sick days taken in workplaces and in the most extreme cases kills residents. It is difficult to think of a more compelling case for action.

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