Air pollution is linked to heart disease

August 31, 2011 Health Care, Medicine, Social Health Community 144 Comments

1.    The Women’s Health Initiative Observational study database of more than 65,000 postmenopausal women without prior CVD evaluated the relation between a woman’s long term exposure to air pollutants and the risk for a first cardiovascular event 1. For each 10 µg/m3 increase in pollution concentration, there were significant increases in the risk of any cardiovascular event (hazard ratio 1.24), death from CVD (hazard ratio 1.76), and of cerebrovascular events (hazard ratio 1.35).

  1. Mortality data from nearly 450,000 patients in the American Cancer Society Cancer Prevention Study II data base showed that PM2.5 (fine particulate matter ≤2.5 micrometers in diameter) 2 but not ozone concentration was significantly associated with the risk of death from cardiovascular causes (relative risk 1.2).
  2. Further support for the importance of air pollution comes from a study of death rates in Dublin, Ireland before and after a ban on coal sales that led to a 70 percent reduction in black smoke concentrations 3. Adjusted cardiovascular deaths fell by 10.3 percent in the six years after the ban.
  3. In addition to long-term risk, short-term exposure to air pollutants (both ozone and fine particulate matter) has been associated with acute coronary ischemic events 4,5.
  4. In a study of over 12,000 patients living in a defined geographic area, a short-term increase in fine ambient particulate matter positively correlated with an increase in acute ischemic coronary events 4,5.
  5. The air pollution: Carbon particulates in the air from the burning of fossil fuels, wood, and other materials scatter and absorb UVB rays. Ozone absorbs UVB radiation, so holes in the ozone layer could be a pollution problem that winds up enhancing vitamin D levels.

Possible mechanisms by which fine particulate air pollution may increase the risk of CVD include

1.    An increase in mean resting arterial blood pressure through an increase in sympathetic tone and/or the modulation of basal systemic vascular tone

2.    An increase in the likelihood of intravascular thrombosis through transient increases in plasma viscosity and impaired endothelial dysfunction

3.       Initiation and promotion of atherosclerosis 6-8.

References

1.    Miller KA, Siscovick DS, Sheppard L, et al. Long-term exposure to air pollution and incidence of cardiovascular events in women. N Engl J Med 2007; 356:447.

2.    Jerrett M, Burnett RT, Pope CA 3rd, et al. Long-term ozone exposure and mortality. N Engl J Med 2009; 360:1085.

3.    Clancy L, Goodman P, Sinclair H, Dockery DW. Effect of air-pollution control on death rates in Dublin, Ireland: an intervention study. Lancet 2002; 360:1210.

4.    Pope CA 3rd, Muhlestein JB, May HT, et al. Ischemic heart disease events triggered by short-term exposure to fine particulate air pollution. Circulation 2006; 114:2443.

5.    Ruidavets JB, Cournot M, Cassadou S, et al. Ozone air pollution is associated with acute myocardial infarction. Circulation 2005; 111:563.

6.    Brook RD, Brook JR, Urch B, et al. Inhalation of fine particulate air pollution and ozone causes acute arterial vasoconstriction in healthy adults. Circulation 2002; 105:1534.

7.    Pekkanen J, Peters A, Hoek G, et al. Particulate air pollution and risk of ST-segment depression during repeated submaximal exercise tests among subjects with coronary heart disease: the Exposure and Risk Assessment for Fine and Ultrafine Particles in Ambient Air (ULTRA) study. Circulation 2002; 106:933.

8.       Sun Q, Hong X, Wold LE. Cardiovascular effects of ambient particulate air pollution exposure. Circulation 2010; 121:2755.