Air pollution is a cause of cardiovascular disease: New York City is not exempted

One of the mega-trend in 21st century is the rising pollution in China and other countries.

Previous reports have linked increasing pollution to heart disease (such as: Kristin A. Miller et al.  Long-Term Exposure to Air Pollution and Incidence of Cardiovascular Events in Women. N Engl J Med 2007; 356:447-458). In 2000, levels of PM2.5 exposure varied from 3.4 to 28.3 μg per cubic meter (mean, 13.5). Each increase of 10 μg per cubic meter was associated with a 24% increase in the risk of a cardiovascular event (hazard ratio, 1.24; 95% confidence interval [CI], 1.09 to 1.41) and a 76% increase in the risk of death from cardiovascular disease (hazard ratio, 1.76; 95% CI, 1.25 to 2.47). For cardiovascular events, the between-city effect appeared to be smaller than the within-city effect. The risk of cerebrovascular events was also associated with increased levels of PM2.5 (hazard ratio, 1.35; 95% CI, 1.08 to 1.68).

The postulated physiology is as follows (from Qinghua Sun et al. Circulation.2010; 121: 2755-2765): inhaled, insoluble PM2.5 or PM0.1 could rapidly translocate into the circulation, with the potential for direct effects on homeostasis and cardiovascular integrity. The ability of PM0.1 to cross the lung-blood barrier is likely to be influenced by a number of factors, including particle size and charge, chemical composition, and propensity to form aggregates. Once in the circulation, PM0.1 can interact with the vascular endothelium or have direct effects on atherosclerotic plaques, causing local oxidative stress and proinflammatory effects similar to those seen in the lungs. Through either direct translocation into the circulation or secondary pulmonary-derived mediators, PM augments atherogenesis and causes acute adverse thrombotic and vascular effects.

However, you will be mistaken if this problem is only restricted to China or some industrial cities. This week NYU published a study linking air pollution in NYC to carotid artery atherosclerosis (Newman JD, Thurston GD, Cromar K, et al. Particulate Air Pollution and Carotid Artery Stenosis. J Am Coll Cardiol. 2015;():. doi:10.1016/j.jacc.2014.12.052.)  Within New York City, they found a nearly 2-fold increase in carotid artery stenosis (odds ratio [OR]: 1.90, 95% confidence interval [CI]: 1.35 to 2.66) for every 10-μg/m3 increase in PM2.5.

NYC city department of health published data on effect of air pollution to health in 2011.  The PM2.5-attributable cardiovascular hospitalization rate is 60% higher in neighborhoods with high, as compared to low, poverty rates. In my community Sunset Park, Brooklyn, the rate is not high. Sections of the Bronx, especially the South Bronx; Upper Manhattan; North-Central and Southern Brooklyn; Eastern Queens; the Rockaways; and Northern Staten Island typically have higher rates of particulate matter-related emergency room and hospital visits, and/or deaths.  Annually, about 7200 admissions to hospitalization in NYC are related to respiratory disorder from air pollution, and another 920 admissions are secondary to cardiovascular disorder secondary to pollution. While most of the health problem from pollution is related to lung problems, cardiovascular system is affected also.

Despite the low rate of pollution in Sunset Park, Brooklyn, we are seeing a lot of pollution related diseases because a lot of my patients are from China, where they have been exposed to high level of air pollution. Therefore, many of my patients have sign of bronchiectasis on lung CT despite being non-smokers, and lung cancer in non-smokers is not rare. Not infrequently, my stable patients ended up with stroke while visiting China, and in my mind some of these are pollution related.

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