Lack of exercise, smoking, a lot of stress: It has long been known that these and other factors promote heart attacks. However, the population is hardly aware of another, largely invisible danger: polluted air. Pollutants enter the airways, can lead to chronic pneumonia and put a heavy strain on the heart.
A new study by researchers with the participation of the Berlin-Brandenburg Heart Attack Registry and the Charité shows that heart attacks in Berlin occurred significantly more frequently on days with high nitrogen oxide (NOx) pollution.
The incidence of heart attacks increased with rising nitrogen oxide concentrations: by one percent for every increase of ten micrograms of nitrogen oxide per cubic meter of air (abbreviated: 10 µg/m³).
In Berlin last year, the scientifically supported reference value for nitrogen dioxide (NO2) was significantly exceeded at 20 of 24 measuring stations. According to the World Health Organization, it is ten micrograms per cubic meter per year. The nitrogen oxide pollution in 2021 was the worst at the three measuring stations Spandauer Damm (38 µg/m³), Herrmannplatz (36 µg/m³) and Silbersteinstraße (35 µg/m³), as can be seen from the publicly accessible air data from the Federal Environment Agency.
The study is based on data from around 18,000 patients who suffered a heart attack between 2008 and 2014. The data were collected from around 30 participating clinics in the heart attack registry. Nitrogen oxide escapes mainly from the exhaust of diesel vehicles, from industrial plants and sometimes also from wood stoves.
According to the analysis, more Berliners suffered a heart attack when the concentration of fine dust with a particle size of ten micrometers and smaller (abbreviated as PM10) was high for three consecutive days beforehand. Like nitrogen oxides, particulate matter can promote respiratory and cardiovascular diseases and is mainly produced in road traffic due to abrasion on brakes, tires or the road surface.
The study has not yet been published in any scientific journal and has not been reviewed for it. The results are to be presented at a conference of the European specialist society of cardiologists in Barcelona at the end of August.
Cardiologist and lead author Ina de Buhr-Stockburger from the Berlin-Brandenburg Heart Attack Registry is quoted in a statement on Tuesday: “The association between air pollution and heart attacks was not found in smokers in our study. This could indicate that bad air causes heart attacks, as smokers who continuously inhale pollutants appear to be less affected by other external pollutants.”
For their analyses, the researchers investigated the connection between the occurrence of a heart attack and the average pollutant concentrations on the same day, the previous day and over a period of three previous days.
The experts also took into account gender, age and whether the patients had diabetes at the time of the heart attack. The study authors received data on solar radiation, temperature and precipitation from the weather station in Berlin-Tempelhof.
The hotter it was in Berlin, the fewer heart attacks occurred – the frequency decreased by six percent at temperatures that were ten degrees higher than at lower temperatures. Neither sun exposure nor precipitation were associated with heart attacks.
“The study shows that polluted air is a risk factor for heart attacks and that more efforts need to be made to reduce pollution from traffic and combustion processes,” says study author de Buhr-Stockburger.
Meltem Kutlar Joss is also familiar with the consequences of polluted air – she is an environmental scientist at the Swiss Tropical and Public Health Institute (Swiss TPH) in Basel and heads the Air Hygiene Documentation Center (Ludok). “More heart attacks with high levels of nitrogen oxide are plausible. The study results match the current state of research,” says the researcher in an interview with the Tagesspiegel.
However, the health-damaging consequences of nitrogen oxides cannot yet be assigned as clearly as is the case with fine dust. “It is possible that other traffic-related pollutants such as ultrafine particles instead of nitrogen oxides pose a much greater health risk,” says Kutlar Joss.
“Ultra-fine dust” refers to particles in the air that have a diameter of between one and 100 nanometers and are therefore even smaller than the two frequently measured fine dust fractions PM10 and PM2.5.
Gudrun Weinmayr, epidemiologist and research associate at the University of Ulm, points out in an email that initial studies on the long-term effects of air pollution indicate serious consequences: “There is another series of diseases for which there are connections or the first ones Evidence has been found – such as stroke, diabetes, cancer and probably even dementia.”
Since 2008, limit values for air pollutants have been in force in the European Union, which in some places are far above the scientifically based guide values of the World Health Organization. So are the results of the Berlin study an indication that disregarding them can have serious health consequences for the population?
Kutlar Joss from Swiss TPH says: “Definitely. If there are more pollutants in the air than the scientific guideline suggests, it means more cardiovascular and respiratory diseases and more premature deaths.”
Improved air quality could reduce the burden of disease in the population and reduce the number of premature deaths.
“Many critics brush aside air pollution concerns, saying the risks are small. But the pollutants work over time and increase the risk of diseases in all sections of the population – from children to adults to the elderly.”
At most measuring stations, the values for pollutants such as fine dust or nitrogen oxides are below the legally specified limit values. If the stricter and scientifically reliable WHO guideline values were to apply in the EU and thus in Germany instead, it would become clear that the air in many places is polluted with fine dust (PM2.5) and nitrogen oxides (NO2) and is a health hazard.
Air pollution is a global problem: Some 4.5 million people died prematurely in 2019 from exposure to outdoor air pollution, according to a report published in May in The Lancet Planetary Health. Globally, polluted air is far more deadly than drug and alcohol abuse, malnutrition or diseases such as AIDS, tuberculosis and malaria, according to the study.
