(NaturalNews) It would be natural to think that microscopic particles in polluted air would do damage to one's lungs, nose and throat. However, recent research published in Circulation: Journal of the American Heart Association has reported that such particles can in fact negatively affect the ability of the heart in people with serious coronary artery disease to conduct electrical signals.
Details of Study
The study looked at 48 coronary artery disease patients who lived in the Boston area, all of whom had previously experienced hospital procedures to open up or examine their coronary arteries.
The group of them had been hospitalized because of deteriorating symptoms of stable coronary artery disease, unstable angina, or a heart attack. Their median age was 57 years and more than 80% were men. In addition, 1 out of 4 had diabetes, while 2 out of every 5 had had a heart attack.
The study team followed up with the patients about two to four weeks post-discharge, and then another three more times at interval periods of about 3-months.
Holter monitors, which are portable electrocardiographs, were used to record the participants' heart activity and to help obtain indications of events such as lack of blood flow to the heart or a heart muscle which was inflamed. Should such situations present themselves, a conductivity change, called an "ST-segment depression", would show up on electrocardiograms.
These measurements were then compared with the levels of certain pollutants, including particulate matter with a diameter less than 2.5 micrometers (or 1/10,000th of an inch), also called PM2.5, and black carbon, which is produced during the incomplete combustion of fossil fuels.
For all the pollutants which were included in the analysis, mean 24-hour levels were within the National Air Quality Standard limits. This meant that air quality was generally considered healthy.
Findings of Study
"We found that an elevation in fine particles, from non-traffic as well as traffic sources, and black carbon, a marker for traffic, predicted ST-segment depression," said Diane R. Gold, M.D., M.P.H., senior author of the study, which involved researchers from the Harvard School of Public Health and the Harvard Medical School in Boston, Mass.
"Effects were greatest within the first month after hospitalization, and for patients who were hospitalized for a heart attack or had diabetes," added Gold.
Another pollutant associated with ST-segment depression was sulfur dioxide, which can also originate from non-traffic sources. There was no significant correlation obtained between ST-segment depression and the levels of carbon monoxide, although it should be noted that levels of the latter were generally low for this study.
Broadly speaking, these findings are consistent with previous studies, which have shown the link between increased particulate air pollution and risk of heart attack or cardiac death, as well as exposure to road traffic triggering off heart attacks. For example, in a study published in 2002, it was reported that cardiovascular deaths decreased by 10 percent in Dublin, Ireland, after coal sales were banned and concentrations of black smoke in the air dropped by 70 percent within the next 3 years.
While the ST-segment changes which the study team observed were not associated with actual physical symptoms in the subjects, nevertheless, their findings provide further evidence that unclean air can affect heart health, either through reduction of blood flow or heart muscle inflammation.
While the question remains as to how air pollution causes ST-segment depression – Gold said that "further research is needed to evaluate whether the pollution-related ST-segment depression that we see is related to increased heart muscle inflammation, reduced oxygen flow, oxidative stress, or increased risk of arrhythmias" – enough is probably known for now for those at risk to take some action.
"We think that our findings, which are definitely subclinical, may represent a process that increases clinical risk for people with symptomatic coronary artery disease," Gold said. The research team also said that their findings suggest that physicians and heart patients be extra careful in the weeks immediately after discharge from hospital.
If you or a loved one has heart problems, then you may want to take note.
The American Heart Association recommends that some heart patients, especially those who have had a heart attack, do not drive for two to weeks after being discharged and also avoid driving in heavy traffic because of the stress such a situation creates.
"Our study provides additional rationale to avoid or reduce heavy traffic exposure after discharge, even for those without a heart attack, since traffic exposure involves pollution exposure as well as stress," said Gold.
Certain additional precautionary steps may also be useful, such as making sure one is not exposed to other forms of air pollution, for example construction sites, and the use of air purifiers to improve the quality of air in the home.