Exposure to air pollution can affect an individual’s mortality risk more than 30 years after the event, according to a study published in the journal Thorax.
The report is the result of one of the world’s longest-running air pollution studies, which tracked the health of 368,000 people in England and Wales over a 38-year period. The team, from Imperial College London, measured air pollution levels in ten-year intervals, using measurements from Britain’s historic air pollution monitoring networks.
The most common health conditions exacerbated by air pollution are bronchitis, emphysema and pneumonia. Air pollution also affected mortality risk from cardiovascular diseases, such as heart disease.
Dr Anna Hansell, the study’s lead author, said: ‘Air pollution has well established impacts on health, especially on heart and lung disease. The novel aspects of our study are the very long follow-up time and the very detailed assessment of air pollution exposure, using air quality measurements going back to the 1970s.
‘Our study found more recent exposures were more important for mortality risk than historic exposures, but we need to do more work on how air pollution affects health over a person’s entire lifetime.’
‘We were surprised to find pollution has effects on mortality that persist over three decades after exposure.’
The researchers assessed levels of black smoke and sulphur dioxide air pollution, both of which are measures of small particles in the air, and produced mainly by burning fossil fuel.
They reported risks from exposure to pollution in units of 10 micrograms per cubic metre of air. Researchers compared these levels of exposure with data on disease and deaths. The study suggests that for every additional unit of pollution that people were exposed to in 1971, the risk of mortality in 2002 to 2009 increased by two per cent.
Dr Rebecca Ghosh, the study’s co-author, said: ‘Putting this in context, an individual who lived in a higher polluted area in 1971 had a 14 per cent higher risk of dying in 2002 to 2009 than someone who had lived in a lower polluted area. An individual living in a higher polluted area in 2001 also had an increased risk of mortality of 14 per cent compared to someone in a low pollution area.’