The UK is second only to Italy in Europe for the highest number of annual deaths from nitrogen dioxide (NO2), a major air pollutant. The toxic gas is mostly caused by diesel vehicles and is linked to lung problems.
The European Environment Agency said the UK had 11,490 premature deaths.
The UK is home to the worst NO2 hotspot in Europe. Marylebone Road in London recorded the highest annual mean levels of the pollutant, more than double than double the legal EU limit.
Across Europe, the EEA estimated that 71,000 people died prematurely in 2013