JOIN USAir pollution can cause significant damage to the heart structure and function, raising the risk of cardiac diseases and death, a new study warns.
"There is strong evidence that particulate matter (PM) emitted mainly from diesel road vehicles is associated with increased risk of heart attack, heart failure and death," said Nay Aung, from the Queen Mary University of London in the UK.
The study examined whether PM2.5 may damage the heart directly. It included 4,255 participants.
Cardiac magnetic resonance imaging was conducted to measure left ventricular volume (structure) and left ventricular ejection fraction (function).
Annual average exposure to PM2.5 was calculated based on participants' home address.
Researchers adjusted for factors that could influence health such as age, gender, diabetes and blood pressure.
"We found that as PM2.5 exposure rises, the larger the heart gets and the worse it performs. Both of these measures are associated with increased morbidity and mortality from heart disease," said Aung.
The researchers also looked for potential factors that could modify the relationship.
They found that people with degree-level education were less prone to having a larger heart and had a smaller reduction in ejection fraction when exposed to PM2.5 than people with a lower level of education.
"This could be due to a number of factors including better housing and workplace conditions, which reduce pollution exposure," said Aung.
"Educated people may also be more aware of their health, have healthier lifestyles, and have better access to healthcare," he said.
"We found that the average exposure to PM2.5 in the UK is about 10 microgrammes per cubic metre in our study. This is way below the European target of less than 25 microgrammes per cubic metre and yet we are still seeing these harmful effects," Aung said.
"This suggests that the current target level is not safe and should be lowered," he said.
Regarding how pollution might have these negative effects on the heart, Aung said PM2.5 causes systemic inflammation, vasoconstriction and raised blood pressure.
The combination of these factors can increase the pressure in the heart, which enlarges to cope with the overload.
The heart chamber enlargement reduces the contractile efficiency leading to reduction in ejection fraction.
"Our results suggest that PM2.5 is linked with negative changes in the heart structure and function that are associated with poor outcomes," said Aung.