Even low levels of air pollution tied to heart damage

Air filters to curb indoor pollution can improve blood pressure

A Syrian doctor checks a child injured during a bombing after a surgery at a hospital in Syria’s rebel-held Idlib province on Sept 10. (AFP)

LONDON, Sept 15, (RTRS): People exposed to even low levels of air pollution are more likely to develop structural changes in the heart that can be a precursor to heart failure, a UK study suggests.

While exposure to air pollution has long been linked to an increased risk of heart attacks and strokes, less is known about how pollutants might alter the structure and function of the heart, the study team writes in Circulation.

Researchers looked at data on exposure to traffic-related air pollution and results from heart MRIs for 3,920 adults who did not have cardiovascular disease. They found that previous exposure to tiny particles known as PM2.5, which include dust, dirt, soot and smoke, and to nitrogen dioxide, a poisonous gas in car exhaust, were associated with enlargement on both sides of the heart.

“Air pollution appears to be damaging for cardiovascular health even at a relatively low exposure level,” said lead study author Nay Aung of Queen Mary University of London.

Individuals exposed to higher level of air pollutants were more likely to have larger cardiac ventricles (main pumping chambers) after accounting for potential factors that can independently influence the size of these chambers, Aung said by email.

“This is important because these observed changes in the heart were similar to the patterns seen in heart failure development,” Aung said.

To assess exposure to traffic fumes, researchers examined data on average annual air pollution levels at participants’ home addresses at the start of the study.

Half of the participants were exposed to average annual concentrations of less than 9.9 micrograms of PM2.5 particles per cubic meter of air (ug/m3) and 28.2 ug/m3 of nitrogen dioxide.

For fine particulate matter, that’s well within UK guidelines limiting average exposure to no more than 25 ug/m3 of PM2.5, although the World Health Organization (WHO) has said there are no safe limits for PM2.5 exposure, Aung and colleagues note in Circulation.

Researchers measured participants’ heart structure with MRIs a median of 5.2 years after assessing their air pollution exposure.

For every extra 1 ug/m3 of PM2.5 and every additional 10 ug/m3 of nitrogen dioxide people were exposed to near their homes, their hearts were enlarged by approximately 1 percent, the study found.

The type of enlargement seen in the study is a “well-recognized . . . adaptation heralding heart failure development,” the authors note.

Heart failure happens when the heart muscle is too weak to pump enough blood through the body. Symptoms can include fatigue, weight gain from fluid retention, shortness of breath and coughing or wheezing. Medications can help strengthen the heart and minimize fluid buildup in the body.

The study wasn’t a controlled experiment designed to prove whether or how air pollution might directly cause enlargement in the heart.

Causes

It’s possible that when people inhale polluted air it causes inflammation in the lungs and blood vessels and fine particulate matter enters the bloodstream, said Benjamin Horne, director of cardiovascular and genetic epidemiology at Intermountain Medical Center Heart Institute in Salt Lake City, Utah.

This can overwork the heart, Horne, who wasn’t involved in the study, said by email.

“Even people who are free from cardiovascular disease may, over time, develop diseases due to chronic exposure to air pollution,” Horne said.

Seniors living in housing with poor indoor air quality may have healthier blood pressure when they use portable air filters than when they don’t have these devices, a small experiment suggests. Exposure to so-called PM2.5 – tiny particles of dust, dirt, soot, and smoke – has long been linked to an increased risk of cardiovascular diseases, researchers note in JAMA Internal Medicine. But less is known about whether portable air filters might help reduce this risk.

The current study involved 40 nonsmokers living in low-income housing for seniors in Detroit, Michigan. The residence was located near major roadways and industrial facilities that release fine particulate matter into the air.

Residents’ blood pressure was measured after they used three different types of portable air filters, each for three days at a time: a low-efficiency air filter; a high efficiency particulate arrestance (HEPA) filter; and a sham filter that didn’t clean the air at all.

Compared to when they used the sham filter, the seniors’ average exposure to PM2.5 indoors was 31 percent lower with the low-efficiency filter and 53 percent lower with the HEPA filter.

And with use of the air filters, blood pressure levels in people with hypertension improved by an amount similar to what might be achieved with lifestyle changes like increased exercise or reduced salt consumption, said lead study author Masako Morishita of Michigan State University in East Lansing.