Research Highlights: Exposure to Air Pollution May Increase Risk of Coronary Events

Exposure to Air Pollution May Increase Risk of Coronary Events

A study published in the British Medical Journal (BMJ) has found strong associations between acute coronary events and exposure to air pollution. Air pollution has become an increasingly serious problem in the world and may cause millions of deaths annually. Recently, many studies have suggested that air pollutants could be linked to heart failure and other cardiovascular-related deaths. The BMJ study furthered this research by investigating the relationship between air pollution exposure and incidence of acute coronary events in several European countries.
11 cohort studies conducted in Finland, Sweden, Germany, Denmark and Italy made up this entire study. In total, 100,166 people with no previous coronary events participated. The study enlisted participants from 1997 until 2007 with the mean participant follow-up time being 11.5 years. Experimenters recorded air pollution exposure in the five European countries by using a series of filters to measure soot and black carbon levels in the air, and by measuring nitrogen oxide levels. Experimenters then used participants’ hospital records to check the amount of coronary events participants experienced throughout the study. Potential confounding variables such as the marital status, education, lifestyle, physical activity levels, and occupation of the participants were also recorded. Finally, the experimenters used statistical tests to determine the association between air pollution exposure and coronary events in participants.
Of the 100,166 people enrolled in the study, 5,157 experienced coronary events. Results showed that increases in levels of certain types of air pollutants were strongly associated with a 12-13% increased risk of coronary event incidence. Experimenters found other smaller associations between air pollutants and coronary health but deemed these statistically insignificant. Therefore, the results of this study strongly suggest that exposure to air pollution increases an individual’s risk of experiencing a coronary event.
Though the results of this study agree with past studies, as well as cohort studies conducted in the United States, researchers noted that some of the study’s results could have been caused by factors other than air pollution. For example, cohort studies with younger participants and higher rates of smoking among participants showed air pollution to have a smaller effect on coronary health. Another weakness of the study was that experimenters were only able to examine variation in air pollution levels within a cohort study (i.e. within one area of one country). They were not able to examine differences in air pollution between different cohort studies in different countries. Overall, however, this study provides new information about the serious effects of air pollution on individual health and demonstrates the urgency of limiting air pollution in the modern world.
BMJ 2014;348:f7412

Caroline Russell-Troutman is the 2013-2014 Research Highlights Editor