Among nonsmokers, data showed a link between higher concentrations of air pollution and greater MI incidence in Germany, researchers reported at the European Society of Cardiology Congress.

“The correlation between air pollution and heart attacks in our study was absent in smokers,” Insa de Buhr-Stockburger, MD, of Berlin Brandenburg Myocardial Infarction Registry, said in a press release. “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.”

De Buhr-Stockburger and colleagues analyzed data from 17,873 MI cases from 2008 to 2014, using the Berlin Brandenburg Myocardial Infarction Registry, as well as detailed regional air pollution data provided by the BLUME network, including daily levels of nitric oxide and particulate matter with a diameter of less than 10 µm (PM₁₀), grouped by region (downtown, main roads, suburbs). Preceding days (single and 3-day average) were also assorted to every single day. Researchers also assessed ambient temperature, precipitation and sunshine duration from the Berlin-Tempelhof weather station.

The researchers analyzed associations between the incidence of acute MI and average pollutant concentrations on the same day, the previous day and an average of the 3 preceding days among all patients and according to baseline characteristics.

Researchers found MI was significantly more common on days with high nitric oxide concentrations, with a 3.2% higher incidence for every 10 µg/m³ increase on the same day (P < .001). MI was also more common when there was a high average PM₁₀ concentration during the 3 preceding days, with a 4.8% higher incidence for every 10 µg/m³ increase (P < .001).

Incidence of MI among smokers was unaffected by nitric oxide and PM₁₀ concentrations. Researchers also observed that incidence of MI was related to the maximum temperature, with a 6% lower incidence for every 10°C rise in temperature (P < .001).

There were no associations with sunshine duration and precipitation.

“The study indicates that dirty air is a risk factor for acute myocardial infarction, and more efforts are needed to lower pollution from traffic and combustion,” de Buhr-Stockburger said in the release. “Causation cannot be established by an observational study. It is plausible that air pollution is a contributing cause of myocardial infarction, given that nitric oxide and PM₁₀ promote inflammation, atherosclerosis is partly caused by inflammatory processes and no associations were found in smokers.”