Rapid increases in nitrogen oxide air pollution may be as harmful to the heart as exposure to sustained high levels, according to research published this month
The research, carried out by scientists at University Hospital Jena in Germany and published in the European Journal of Preventive Cardiology evaluated the association between rapid changes in air pollutants and the risk of myocardial infarction independently of ‘absolute’ concentrations.
It also looked at whether an association between heart attacks and changes in air pollution exists in “clean air cities”, where concentrations of air pollution vary but do not exceed EU limits.
The study was conducted in Jena a city with 100,000 residents where concentrations of some air pollutants exceeded EU daily limits on a handful of days over the last few years.
Heart attack patients living within 10km of Jena, and who were admitted to Jena University Hospital between 2003 and 2010, were included in the study, with 693 cases identified overall.
Researchers looked at the concentrations of air pollutants one, two, and three days before heart attack symptoms arose were compared to concentrations in both the previous and following weeks.
They found that increases of nitrogen oxides of more than 20 μg/m3 within 24 hours of symptoms were associated with a more than doubled risk of heart attack.
“This strong association surprised us as it is almost linear,” said Dr Florian Rakers, senior author of the study.
Professor Dr Matthias Schwab, Senior Consultant at the University Hospital Jena Department of Neurology and co-author of the study added: “The acute risk of heart attack in our study approximately doubled when the nitric oxide concentration increased by 20 micrograms per cubic metre within one day.”
The British Heart Foundation has described the findings of the report as ‘further evidence of the daily danger people face from breathing dirty air’.
Commenting on the study Professor Metin Avkiran, Associate Medical Director at the British Heart Foundation, said: “We already know that air pollution, including various gases and small particles, contributes to an estimated 40,000 premature deaths in the UK each year. This research indicates that even temporary increases in nitrogen dioxide levels may elevate the risk of having a potentially fatal heart attack.
“If confirmed by larger studies, this is likely to reshape thinking around the impact of air pollution on heart-health, to take into account the importance of sharp increases in pollution levels. We also need research to determine how a temporary increase in nitrogen dioxide levels might trigger a heart attack.
“There is now a wealth of evidence which clearly demonstrates the harm air pollution causes. Adopting the World Health Organisation’s air quality guidelines would help ensure the nation’s heart health is better protected from the potential risks they pose.”