For those who live in industrial areas, large cities or urban areas, air quality -- or rather the lack thereof -- can be problematic. Many of us are well familiar with the various ozone action days or smog alerts advising children, the elderly, and those with asthma, pulmonary diseases, respiratory and other breathing difficulties to remain indoors.
Such alerts are issued because it’s generally accepted that air pollutants negatively impact the health of persons falling into these categories and that prolonged exposure may result in serious health complications or even death.
The effect of exposure to air pollutants on health has been the subject of numerous studies, particularly since the 1990s. The National Institute of Environmental Health Sciences began funding research to study the long-term effects of air pollutants on heart disease and respiratory health as early as 1974 in a study which came to be known as the Six Cities Study.
These early studies indicated that persons living in areas where they had a high exposure to air pollutants were at a greater risk of hospitalization and death from heart or pulmonary diseases than their counterparts living in non-polluted areas.
However, not all studies concurred with the findings. As it relates to heart disease, study results have been mixed with some reporting no impact on an increased risk of heart attack, while the findings from other studies report the opposite.
Results from a new study examining the relationship between short-term exposure to air pollutants and the risk of heart attack were released today in the Journal of the American Medical Association or JAMA. Led by Hazrije Mustafic, M.D., M.P.H, of the University of Paris Descartes, researchers analyzed the findings from 34 different studies relating to a potential correlation between heart attack risk and exposure to air pollutants.
The various substances considered in the study included air pollutants such as carbon monoxide, sulfur dioxide, ozone, nitrogen dioxide, and particulate matter. Study findings indicated that even short-term exposure to air pollutants increased the risk of heart attack.
Researchers believe that the increased heart attack risk is due in part to three mechanisms:
• Inflammation. Exposure to air pollutants cause inflammatory marker levels to increase. Inflammatory markers such as C-reactive protein are linked to an increased risk of heart attack.
• Abnormal Heart Regulation. Exposure to air pollutants is linked to higher than normal heart rates along with decreased heart rate variability.
• Blood Viscosity. Exposure to air pollutants causes the blood viscosity, or thickening. This viscosity leads to an increase in atherosclerosis progression and blood clot formation or thrombosis.
Researchers acknowledge that this study is small when compared to some studies examining traditional heart attack risk factors. However, given the number of living in urban areas, researchers believe that improving air quality could play a major role in improving health. Additional research is required to determine if the rate of heart attack decreases as air quality improves.
Sources:
Short-Term Exposure to Most Major Air Pollutants Associated With Increased Risk of Heart Attack. (JAMA. 2012;307[7]:713-721. Available pre-embargo to the media at
http://www.jamamedia.org
Air Pollution & Cardiovascular Disease. National Institute of Environmental Health Sciences.
http://www.niehs.nih.gov/health/impacts/cardiovascular
Reviewed February 14, 2012
by Michele Blacksberg RN
Edited by Jody Smith