Latest UK air pollution data: NO2 continues to fall, PM2.5 stable

The Department for Environment, Food and Rural Affairs (Defra) has published its annual air quality statistics update, which shows that nitrogen dioxide (NO2) continued to fall in 2019 whilst fine particulate matter (PM2.5) has barely moved in towns and cities since 2015.

The report summarises the concentrations of particulates (PM10, PM2.5), NO2 and ozone (O3) from monitoring sites measured by the Automatic Urban and Rural Network (AURN) and also covers the number of days when levels of any these four pollutants, plus sulphur dioxide (SO2) was ‘moderate or higher’.

With sales of diesel vehicles falling year-on-year and the UK continuing its move away from coal-power, 2019 saw the lowest average annual mean concentrations for NO2 since records began in 1987, for both roadside and urban background monitoring sites.

Between 2006 and 2019, the annual mean NO2 concentration at urban background sites has reduced by an average of 1.0 μg/m3 a year.

There were also on average fewer hours of moderate or higher levels of nitrogen dioxide pollution in 2019 compared with 2018 at roadside sites. This continues a trend for reduction in short-term moderate or high NO2 pollution since 2007, mainly due to reductions in this measure at monitoring sites in London.

The picture for PM2.5 was less positive, where levels have stayed stable from 2015 to 2019 for both roadside and urban background sites. 

The number of hours of moderate or higher levels of particulate matter (PM10/PM2.5) pollution has reduced in the long term, but there was an increase in the number of hours of moderate or higher PM2.5 pollution recorded in 2019 compared with 2018 at both roadside and urban background sites.

The data revealed that O3 pollution has remained fairly stable between 2003 and 2019, although daily maximum eight-hour mean concentrations have shown a long-term increase since monitoring began.

O3 is not emitted directly in significant quantities but is created in the air through chemical reactions between other pollutants in sunlight, with more being created on hot, still, sunny days, with researchers attributing the high levels to the UK’s hot summer.

When combining all the pollutants, there was a greater number of days of moderate or higher pollution at monitoring sites in 2019 compared with 2018. 

Read the full report here.


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