A multi-ethnic, longitudinal cohort study, conducted within six metropolitan areas in the USA between 2000-2010, shows an association between air pollution and calcification in the coronary artery.

According to the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), published in The Lancet on May 24th, 2016, long term exposure to even low levels of air-pollutants, deposits calcium in the arteries and could lead to cardiovascular problems.

According to this in-depth study, exposure to air pollutants resulted in an increase in the rate of calcification of the coronary artery by 24 Agatston unite per year and associated intima-media thickness by 12µm per year. Spanning over 10 years i.e., from 2000-2010, the study enrolled more than 6,000 Americans who were exposed to pollutant concentrations ranging from 9.2-22.6µg PM 2-5 /m3 and 7.2-139.2 parts per billion NOX. For each 5µg PM 2-5/m3 and 40 ppb NOX increase in the air, the deposition of coronary calcium rose by 4.1 Agatston units per year and 4.8 Agatston per year, respectively.

Intima-media thickness, also known as intimal medial thickness (IMT) is a measurement of the thickness of tunica intima and tunica media, the two innermost wall layers of an artery. It is mentioned in the study that pollutant exposure was not associated with IMT changes.

Insight Into Air Pollution And The Study

The participants included in this study belonged to six metropolitan cities: Baltimore, Chicago, Los Angeles, New York, St Paul and Winston-Salem. 39% of participants were white, 27% black, 22% Hispanic and 12% Chinese. Every participant was tested for exposure to ambient particulate matter less than 2.5 microns in diameter (too small to be seen by the naked eye), as well as to other materials present in the traffic and air pollution, such as nitrogen oxide, nitrogen dioxide and black carbon or soot.

“Particulate Matter” is a term used for the mixture of solid particles and liquid droplets found in the air. Some particles, such as soot, dirt, dust or smoke are large or dark enough to be seen with the naked eye.

Besides this, the participants were tested for thousands of other air pollution measurements collected from their communities and homes. A few computational models had been developed which encompassed local information on land use, roadway and traffic mass, weather conditions and local sources of air pollution. These models were designed to accurately measure the pollution concentrations at each person’s home.

The MESA Air study was funded in 2004 by the US Environmental Protection Agency (EPA). Other funding for this study came from the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Environmental Health Sciences (NIEHS).

Dr Bert Brunekreef, a professor at Utrecht University in the Netherlands, and Dr Barbara Hoffmann, a professor at the University of Dusseldorf in Germany, labeled the study as exemplary. Considering the outcomes of the study, they called for serious interventions to stop the globally rising pollution levels.

Dissimilarity Between The Old And Current Studies

The previous studies were shorter and dependent on the existing data whereas this study consists of evidence received directly from MESA Air. More than 6,000 people from six metro areas of the US have been considered for the study.

“Besides, this study contains new information on how pollution affects the main biological processes that may result into cardiovascular problems”, said the lead author of the study, Dr Joel Kaufman.

Hazardous Effects Of Nitrogen Oxides (NO) On Health

If the gases in the air cross their threshold level, they can be very deadly for human beings as well as other living things. For example, exposure to high levels of NO can cause rapid burning and swelling of the respiratory tract leading to breathing difficulties, throat spasms and many other associated symptoms.

A long-term exposure can trigger permanent respiratory difficulties. Small levels of NO in the air can cause irritation of the eyes, nose, throat and can sometimes lead to nausea, vomiting and fatigue.