In a study from Berlin Brandenburg Myocardial Infarction Registry, scientists found a causal link between air pollution and heart attacks since smokers, who already inhale smoke, were unaffected by dirty air.
This may indicate that bad air can actually cause heart attacks since smokers, who are continuously self-intoxicating with air pollutants, seem less affected by additional external pollutants.
In the study, the team examined the associations of nitric oxide, particulate matter with a diameter less than 10 µm (PM10), and weather with the risk of a heart attack in Berlin.
Nitric oxide originates from combustion at high temperatures, in particular from diesel vehicles. Combustion is also a source of PM10, along with abrasion from brakes and tires, and dust.
The team tested 17,873 patients with heart attacks between 2008 and 2014.
Regarding pollution, the team found heart attack was much more common on days with high nitric oxide concentrations, with a 1% higher incidence for every 10 µg/m3 increase.
The heart attack was also more common when there was a high average PM10 concentration over the three preceding days, with a 4% higher incidence for every 10 µg/increase.
The incidence of a heart attack in smokers was unaffected by nitric oxide and PM10 concentrations.
Regarding weather, the team found the incidence of heart attack was strongly related to the maximum temperature, with a 6% lower incidence for every 10°C rises in temperature.
No associations with sunshine duration or precipitation were detected.
The study indicates that dirty air is a risk factor for heart attack and more efforts are needed to lower pollution from traffic and combustion.
Causation cannot be established by an observational study.
It is plausible that air pollution is a contributing cause of heart attack, given that nitric oxide and PM10 promote inflammation, atherosclerosis is partly caused by inflammatory processes, and no associations were found in smokers.
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The study was conducted by Dr. Insa de Buhr-Stockburger et al and presented at ESC Congress 2022.
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