Blood type linked to heart-attack risk from high air pollution levels

People with history of coronary problems should avoid smoggy places, scientists recommend

PEOPLE with type O blood have a reduced risk of suffering a heart attack or chest pain during episodes of high air pollution compared with the rest of the population, American scientists have claimed.

Researchers warned that people with type A, B or AB blood should consider staying indoors to minimise their risk if they have underlying heart conditions, such as coronary artery disease.

It has been known for some time that pollution raises the risk of a heart attack but it is the first time that it has been linked to blood type.

A study of 14 years of patient data from the Intermountain Medical Center Heart Institute in Utah found that the risk of a heart attack or chest pain doubled for people of type A, B or AB blood when pollution hit high levels. In contrast, the risk rose by only 40 per cent for those with type O.

“The 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,” said Dr Benjamin Horne, a clinical epidemiologist and the study lead investigator at the Salt Lake City institute, one of the premier cardiac centres in the US, which focuses on the diagnosis, medical management and prevention of cardiovascular disease.

“In the information we provide to our patients about pollution, we try to stress that they can do something about it to reduce their risks: stay indoors out of pollution and exercise indoors.”

Air pollution in Britain is thought to contribute to around 40,000 early deaths a year, according to the Royal Colleges of Physicians and of Paediatrics and Child Health.

Recent research by the World Health Organisation found that 44 major UK towns and cities now breach WHO guidelines on air quality with particulate levels so high they cause six million sick days each year.

Safe levels of air pollution are generally considered to be under 20 micrograms per cubic metre, but during levels of high pollution, the PM2.5 count – the measure of small particulates in the air – rises to around 60micrograms per cubic metre. In London, it has been known to rise to 197mg.

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 it rose by only 10 per cent for people with type O.

Around 55 per cent of people are A, B or AB and they are thought to be at greater risk of heart problems because their blood contains greater quantities of a clotting agent.

The study was presented yesterday at the American Heart Association Scientific Sessions in Anaheim, southern California.