Even comparatively low levels of air pollution boost the chances of an early death, suggests new research.

The researchers base their findings on long term monitoring of air quality in different electoral wards around Britain during different time periods, and national data on causes of death.

More than 5000 adults aged 30 and above were included in the study.

To assess more closely the impact of pollution on health, they divided the data into four chunks, spanning a total of 16 years each, starting in 1966-70 and ending in 1994-8.

Black smoke and sulphur dioxide were strongly linked to the chances of an early death, the findings showed.

But despite a fall in air pollutants over the study period, as measured by the air quality readings, the risk of an early death remained, even at the comparatively low levels of air pollutants during the most recent time frame.

This was especially true for deaths from respiratory illness.

The risk of an early death from respiratory disease rose by almost 4% for every 10 ug/m3 increase in black smoke, and by 13% for every 10 parts per billion increase in sulphur dioxide during 1982-98.

In 1994-8, the comparable figures were more than 19% and almost 22%, respectively.

The figures held true even after adjusting for factors known to increase the chances of an early death, including social deprivation.

Their findings confirm the enduring legacy of air pollution on health, say the authors. And they “point to continuing public health risks even at the relatively low levels of black smoke and sulphur dioxide that now occur.”

Long term associations of outdoor air pollution with mortality in Great Britain