Extensive study on effects of air pollution
Exposure to air pollution more than 30 years ago may still affect an individual’s mortality risk today, according to new research.
The new report comes from one of the world’s longest running air pollution studies, which included 368 000 people in England and Wales followed over a 38-year period.
The team, from the MRC-PHE Centre for Environment and Health, estimated air pollution levels in the areas where the individuals lived in 1971, 1981, 1991 and 2001, using measurements from Britain’s extensive historic air pollution monitoring networks.
Diseases linked with air pollution exposure
Highest risks were seen for respiratory disease, such as bronchitis, emphysema and pneumonia. Air pollution also affected mortality risk from cardiovascular diseases, such as heart disease.
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
“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,” said Dr Anna Hansell, lead author of the study, from the MRC-PHE Centre for Environment and Health at Imperial.
Black smoke, sulphur dioxide and PM10
Researchers assessed levels of black smoke and sulphur dioxide air pollution from 1971 to 1991 and PM10 air pollution in 2001. Both black smoke and PM10 are measures of small particles in the air. Black smoke and sulphur dioxide were produced mainly by burning fossil fuels (including coal, oil, diesel, petrol).
What is PM10?
Today, the methods of measuring air pollution have changed. A common measure is PM10, which measures very small particles that are less than 10 microns in size. These can travel deep into the lungs and may even be small enough to enter the bloodstream. This type of air pollution is mainly produced by transport and industry with a contribution from construction activities and natural sources (e.g. sea salt, soil).
Recent and past exposure to air pollution
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 increases by two per cent.
The researchers also looked at more recent exposure and found a 24 per cent increase in mortality risk in 2002 to 2009 for each additional unit of pollution people were exposed to in 2001.
What does this mean?
“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,” said Dr Rebecca Ghosh, co-author of the study from the School of Public Health at Imperial.
Source: Imperial College London via Sciencedaily.com
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