The ABO gene -; which is present in people who have A, B, and AB blood types -; is the only gene that's been validated in large global studies to predict heart attacks among people with coronary disease. This new study was created to build on and tie together those findings and test the influence of one variation: the impact of an individual's blood type.
The study found that for every additional 10 micrograms over 20, the risk to people with type A, B, or AB blood increased by 25 per cent, but only by 10 per cent for people with type O.
"We wondered, if someone has a specific variation in this ABO gene, are they more or less likely to experience a heart attack in times of higher pollution?" said Dr Benjamin Horne, lead investigator of the study.
'The one that's been found in genetic studies to be lower risk is O. The other three were higher risk'.
However, "this association between heart attacks and pollution in patients with non-O blood isn't something to panic over, but it is something to be aware of", he said.
Safe levels of air pollution are generally considered to be under 20 micrograms per cubic meter, but during levels of high pollution, the PM2.5 count - the measure of small particulates in the air - raise to around 60 micrograms per cubic meter.
Dozens of genes have been shown in large worldwide studies to predict the onset of coronary artery disease in people who are free of the disease.
But the vast majority of people won't have a heart attack unless they already have coronary artery disease.
Results of the study were reported to the 2017 American Heart Association Scientific Sessions in Anaheim, California on Tuesday.
The clinical data used for the study came from Intermountain Healthcare patients seen between 1993 and 2007.
Recent research by the World Health Organisation found that 44 major United Kingdom towns and cities now breach WHO guidelines on air quality with particulate levels so high they cause six million sick days each year.
People who have A, B, and AB blood types carry the ABO gene and the team at the Intermountain Medical Centre Heart Institute in Utah, wanted to find out whether a variant of this gene was linked to elevated risk of heart attacks during periods of high air pollution.
For each 10 additional micrograms of PM2.5 particles per cubic metre, risk for people with non-O blood types goes up by 25 percent, whereas for people with O blood it only goes up by 10 percent. So at the 65 micrograms per cubic meter pollution level, a person with type O blood faces risk that's 40 percent higher than if the air wasn't polluted.
Staying indoors, exercising indoors, compliance with heart medication may help reduce risks, the researchers said.