Link between Atherosclerosis and Air Pollution has been established
Traffic policemen and many people who run small roadside businesses spend extended hours outdoor*, like in traffic and at road junctions, are more vulnerable to the effects of exposure to Air Pollution. Long-term exposure to air pollution may increase risk of heart disease, in addition to other host of health conditions including psychological problems, especially in these people. Though the link between air pollution and heart disease is known but the biological process has not been understood very well so far.
Recent study found that people living in areas with more outdoor pollution accumulate deposits in the arteries that supply the heart faster than do people living in less polluted areas. If this is the case in countries like United States and Other well-developed nations in the world, the situation in countries like India could be unimaginable taking into the fact the condition of roads, dust, vehicle exhaust, traffic conditions, driving behaviors etc., to mention a few.
The current major decade long study results on this were published online in The Lancet (May 24) and the researchers in this study were successful in establishing the link between exposure to particulate matter and to the diseases of the cardiovascular system and it says that…
“Now, direct evidence from the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), a 10-year epidemiological study of more than 6,000 people from six U.S. states, shows that air pollution — even at levels below regulatory standards — accelerates the progression of atherosclerosis. The condition, also called hardening of the arteries, can cause heart attacks.”
Researchers repeatedly measured calcium deposits in the heart’s arteries by using CT scans. They also assessed each person’s exposure to pollution based on home address.
- The participants lived in six major cities across the United States. The clinics were in Baltimore, Chicago, Los Angeles, New York City, St. Paul and Winston-Salem.
- Of the people in the study, 39 percent were white, 27 percent black, 22 percent Hispanic, and 12 percent Chinese
- The researchers…
- calculated each participant’s exposure to ambient fine particulate matter that is less than 2.5 microns in diameter and too small to be seen by the naked eye.
- measured, in addition to PM2.5, exposure to nitrogen oxide and nitrogen dioxide, and black carbon or soot.
- collected thousands of air pollution measurements in the study participants’ communities and at their homes.
- developed and applied computational models that included local information on land use, roadway and traffic volumes, weather conditions, and local sources of air pollution.
- participants visited study clinics several times to undergo CT scanning to determine the amount of calcium deposits in their heart arteries.
The study found that…
- Results were strongest for fine particulate matter and the traffic-related pollutant gases called oxides of nitrogen.
- for every 5 µg/m3 higher concentration of PM2.5, or 35 parts per billion higher concentration of oxides of nitrogen individuals had a 4 Agatston units/year faster rate of progression of coronary artery calcium scores. This is about a 20 percent acceleration in the rate of these calcium deposits.
- The effects were seen even in the United States where efforts to reduce exposure have been notably successful compared with many other parts of the world.
- Exposures were low when compared to U.S. ambient air quality standards, which permit an annual average PM2.5 concentration of 12 µg/m3.
- The participants in this MESA-Air study experienced concentrations between 9.2 and 22.6 µg/m3.
Dr. Joel Kaufman who is the lead author of this Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air) said that “The study provides important new information on how pollution affects the main biological process that leads to heart disease”.
He said “This was the most in-depth study of air pollution exposures ever applied to a large study group specifically designed to examine influences on cardiovascular health.”
Dr. Bert Brunekreef, a professor at Utrecht University in The Netherlands, and Dr. Barbara Hoffmann, a professor of the University of Düsseldorf in Germany, described the study as “exemplary.” Noting that the results are sobering, they called for decisive action in controlling pollution levels worldwide.
*The common sources of outdoor air (ambient air) pollution are emissions caused by combustion processes from motor vehicles, solid fuel burning and industry. Other pollution sources include smoke from bush-fires, dust, etc. The most common air pollutants of ambient air include: Particulate matter (PM10 and PM2.5), Ozone (O3),Nitrogen dioxide (NO2). Carbon monoxide (CO), Sulphur dioxide (SO2)
Some Facts on Link between Air Pollution and Health Conditions, including Cancer, and Mortality/Morbidity
According to World Health Organization,
- The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes.
- Few risks have a greater impact on global health today than air pollution; the evidence signals the need for concerted action to clean up the air we all breathe.
- Indoor air pollution was linked to 4.3 million deaths in 2012 in households especially cooking over coal, wood and biomass stoves. (Poor women and children pay a heavy price from indoor air pollution since they spend more time at home breathing in smoke and soot from leaky coal and wood cook stoves.)
- Outdoor air pollution was linked to 3.7 million deaths in 2012 from urban and rural sources worldwide.
- Regionally, low- and middle-income countries in the WHO South-East Asia and Western Pacific Regions had the largest air pollution-related burden in 2012, with a total of 3.3 million deaths linked to indoor air pollution and 2.6 million deaths related to outdoor air pollution.
- Studies reveal a stronger link between both indoor and outdoor air pollution exposure and cardiovascular diseases, such as strokes and ischaemic heart disease, as well as between air pollution and cancer. (This is in addition to air pollution’s role in the development of respiratory diseases, including acute respiratory infections and chronic obstructive pulmonary diseases).
- breakdown of deaths attributed to specific diseases, underlining that the vast majority of air pollution deaths are due to cardiovascular diseases as follows:
Outdoor air pollution-caused deaths – breakdown by disease:
- 40% – ischaemic heart disease;
- 40% – stroke;
- 11% – chronic obstructive pulmonary disease (COPD);
- 6% – lung cancer; and
- 3% – acute lower respiratory infections in children.
Indoor air pollution-caused deaths – breakdown by disease:
- 34% – stroke;
- 26% – ischaemic heart disease;
- 22% – COPD;
- 12% – acute lower respiratory infections in children; and
- 6% – lung cancer.
“Cleaning up the air we breathe prevents
non-communicable diseases as well as reduces
disease risks among women and vulnerable groups,
including children and the elderly…”
Dr Flavia Bustreo,
WHO Assistant Director-General
Family, Women and Children’s Health