Air pollution linked to 4,800 heart attack patient deaths

British research finds that long-term exposure to particulate matter PM2.5 is responsible for a 12% increase in the mortality rate of heart attack patients in England and Wales

Almost 4,800 early deaths among people with heart problems in England and Wales are caused by long-term exposure to particulate matter PM2.5, according to government-funded research.

A study carried out by the London School of Hygiene and Tropical Medicine, entitled ‘Long-term exposure to air pollution is associated with survival following acute coronary syndrome (ACS)’, investigated whether long-term exposure to air pollution was associated with mortality in survivors of heart attacks. It also analysed the extent to which exposure to air pollution contributed to socioeconomic differences in prognosis.

A UK study investigated whether long-term exposure to air pollution was associated with mortality in survivors of heart attacks

The study authors Dr Cathryn Tonne and Dr Paul Wilkinson estimated that the mortality rate of the monitored patients would be reduced by 12% if they were exposed to naturally occurring PM2.5 rather than their actual modelled exposure.

This reduction translates to 4,783 deaths brought forward due to PM2.5 exposure from man-made sources.

More than 154,000 heart attack and chest pain patients were monitored in England and Wales for an average period of 3.7 years in the study. During this period, there were 39,863 deaths (26% of patients).

Patients living in London had the highest exposure to particulate matter and nitrogen oxides compared with other regions, according to the research. The next highest levels of exposure for PM2.5 were found in south east England, east England and the east and west Midlands.

Overall, the study found that a 10 microgram per cubic metre increase in PM2.5 was associated with a 20% increase in deaths among patients from all causes. However, there was no association found between mortality and other pollutants.

While previous studies have linked heart problems with exposure to particulate matter, this study looked at the effects of exposure on survival and also on subsequent cardiac events among survivors of heart attacks, co-author Dr Cathryn Tonne said.

She commented: “We found an association between long-term exposure to fine particulate matter (PM2.5) and all-cause mortality among patients who had previously had a heart attack.”

However, despite higher exposure to PM2.5 among those from more deprived areas, the study found that such exposure was a minor contribution to the socioeconomic differences in prognosis following Acute Coronary Syndrome (ACS).

Dr Tonne added: “Air pollution doesn’t fully explain the huge differences in how well people do after a heart attack with regards to socioeconomic background — this requires more research. We will be doing similar work on this issue in the future.”

The authors worked for two years on the study, which was funded by the Department for Health and the Economic and Social Research Council.
The study is available on the European Heart Journal website.