Air pollution and associated cardiovascular health

 

Aims: The project is designed to investigate the effects of exposure to airborne pollution on cardiovascular health. Many studies have identified an association between exposure to elevated levels of airborne pollution and increases in morbidity and mortality associated with acute myocardial infarction, heart failures and coronary heart disease. The project investigates the occurrence of these diseases in a low pollution scenario and investigates plausible biomedical causes of the observed increases. The study investigates the composition of airborne particles in the city, as one hypothesis is that particle composition may be as important as the total mass of respired particles.

The project investigates the aetiology of myocardial infarction and heart failure in the city, associated with exposure to air pollution and variations in meteorological conditions. The study aimed to identify to what degree these diseases are affected by changes in environmental conditions. Variations in the composition of the blood were investigated as a possible mediator in the association between air pollution, meteorology and MI and HF. In one study an epidemiological approach was used to investigate changes in the concentrations of blood coagulation factors. The second study used blood obtained from healthy volunteers on high pollution days and low pollution days, accounting for meteorological changes. The samples were analysed for several non-blood coagulation factors, with the capability of adversely altering MI and HF aetiology.

Primary results: The study identified that no significant association is observed between exposure to airborne pollution and morbidity and mortality associated with acute myocardial infarction of heart failure. The gaseous pollution levels in the city were identified as too low to have a significant effect on cardiovascular health, however decreases in outdoor temperature were seen to have a significant detrimental effect on myocardial infarction and heart failure. However air pollution levels were observed to be significantly associated with deaths arising from respiratory disease. The composition of the collected particulate matter was identified as the primary reason of the lack of any association between airborne particulate matter and acute myocardial infarction of heart failure. Daily variations in outdoor temperature are identified as the most significant environmental parameter affecting the occurrence of morbidity and mortality associated with acute myocardial infarction of heart failure.

There was no significant association between exposure to elevated levels of air pollution or decreased temperature and variations in blood coagulation factors. There was also no significant association between changes in non-coagulation blood factors and changes in meteorological and air pollution factors. Two possible explanations exist to explain these results, either air pollution levels are too low to effect blood composition, or the association between air pollution and MI and HF is not mediated through the studied parameters.

Several significant associations were identified between exposure to airborne pollution and changes in non-coagulation blood parameters. These changes, including a variety of changes in white blood cells, the haematocrit and plasma viscosity, all suggest mechanisms by which exposure to airborne pollution may exacerbate myocardial infarction and heart failures. These findings indicate that exposure to airborne pollution has more than a statistical association with MI and HF.

Conclusions: In the city and county of Cardiff levels of primary airborne pollutants is at a much lower level than many other study areas. As a consequence of these differences in air pollution dynamics there is a significant difference in the disease aetiology, particularly associated with MI and FIF. However even in this low pollution environment adverse health effects are noted, including elevation in deaths associated with respiratory disease. The pollution levels identified in Cardiff were associated with changes in several blood parameters, which in other studies are associated with adverse health effects, including exacerbation of MI and HF.