North Shore AIR

Health Impacts: Heart Disease and Stroke

Heart disease is the leading cause of death in Massachusetts.  In 2003, the most recent year for which statistics are available, heart disease accounted for 26 percent of all deaths in the State.

Researchers in both the U.S. and abroad have found a positive association between cardiovascular disease and several air pollutants.  In one study, data was collected on more than half a million people over age 16, then matched with air pollution data gathered by the U.S. EPA.  Researchers found a clear association between air pollution and death rates, especially heart-related deaths.  In fact, 45 percent of all deaths in the study were due to cardiovascular disease.  (Note that respiratory disease accounted for only 8.2 percent of the deaths.) (1)

Studies show that the fine particles and ozone that make up air pollutants are able to travel through the airways and enter the tiny air sacs at the base of the lungs where they can create inflammation and affect circulating blood, helping to trigger cardiac events for those individuals who are at risk for heart disease.

Researchers have also learned that the inhalation of these microscopic particles and ozone causes blood vessels to constrict.  In one study, young healthy volunteers were put into a special chamber where they had to breathe polluted air for two hours.  Measurements were then taken on their blood vessels and were compared to measurements taken on the same volunteers after having been exposed to ozone-free and particle-free air in this chamber.  Their vessels were found to have constricted after breathing the polluted air, but not after breathing the clean air.  The amount of restriction was not great enough to cause problems in healthy people, but could possibly "trigger cardiac events in those individuals who have or are at risk for heart disease." (2)

Given the significance of air pollution to those people who are vulnerable to illness or death from heart disease, the NSAIR project looked at rates of cardiovascular diseases in the three target communities.  Circulatory system disease data includes coronary heart disease, cerebrovascular disease (including stroke), and acute myocardial infarction (heart attack).  The data is compiled in Table 1 below, and more detailed data is available in the appendix.

Salem:
Mortality rates for all circulatory system diseases were elevated when compared with the state. Mortality rates were increased for both the 3 year age-adjusted mortality rate and the 3 year pre-mature mortality age-adjusted rate.  (The pre-mature mortality rate is a measure of persons who died under the age of 75 which is considered a pre-mature death.)  See appendix…

Total hospitalization rates for all heart diseases combined were not elevated.  However, hospitalization rates for males were higher for cerebrovascular disease (stroke) and acute myocardial infarction (heart attack).  Hospitalization rates for females were elevated only for acute myocardial infarction.  See appendix…

Beverly:
Mortality rates from circulatory system diseases for males and females together were only slightly elevated when compared to the State.  This elevation can be attributed to females who showed a much higher death rate for cerebrovascular disease only when compared with the state.  The pre-mature mortality rate (those who die under the age of 75) was not elevated. See appendix 1b for more information

Hospitalization rates for males and females together did not show any elevation when compared with the state, however on closer inspection, the rate of disease for males was found to be elevated in all of the cardiovascular categories—coronary heart disease, cerebrovascular disease, and acute myocardial infarction.  Rates for females were not elevated, which explains why the total was not elevated.

Marblehead:
Total mortality due to heart disease was not found to be elevated in Marblehead. However, males did show a higher rate as compared with the state for cerebrovascular disease. 

The cardiovascular hospitalization rate was not increased.   See appendix 1b for more information

Table 3:  Cardiovascular Hospitalizations - Total by Community

Source: MassCHIP (MA DPH) instant topics, Cardiovascular Health Report.  2001-2003 Hospital Discharges (UHDDS)  Rates are expressed per 100,000 people.

Increased Risk of Stroke