Nitric oxide and particulate matter cause heart attacks in non-smokers

A new study analysing possible causal relationships between air pollution, weather conditions and cardiac incidents has identified a worrying trend.

Researchers have presented new evidence to support the idea of a direct link between heart attacks in non-smokers, and levels of nitric oxide and particulate matter in the air. The findings were presented at ESC Congress 2022. 

Focusing on 17,873 Berlin patients with a myocardial infarction (heart attack) between 2008 and 2014, the team behind the study took into account sex, age, smoking status, and diabetes diagnosis in all those involved. External factors, including the daily PM10 particulate matter and nitric oxide readings, alongside the number of direct sunshine hours, minimum and maximum temperatures, and precipitation level, were also included. 

The incidence of acute heart myocardial infarction were then cross referenced with the pollutant concentrations and weather conditions on the day of the cardiac event, in the previous 24-hours, and preceding three days. Overall, it was found that with every 10µg/m3 increase in nitric oxide, the rate of heart attacks in non-smokers was 1% higher. High average PM10 concentrations in the three preceding days was also linked to more cardiac emergencies, rising 4% for every 10µg/m3 increase. 

Incidence was reduced with warmer weather, running at 6% lower for every 10C rise in temperature. The rate of myocardial infarction among smokers was unaffected by atmospheric pollution, which experts believe is because their lungs, respiratory and cardiovascular systems are already used to an intake of highly polluted and toxic air. 

 ‘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. 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,’ Dr. de Buhr-Stockburger. 

The findings back up a previous study reported by Air Quality News back in April, which suggested even World Health Organisation recommended maximum levels of air pollution may have the potential to cause a heart attack within 60minutes of exposure.

Image credit: Robina Weermeijer