While many studies have shown that air pollution is linked to negative health impacts including poor cardiovascular health, it's been difficult to determine exactly how the two are connected. Air pollution tends to contain toxic gases, including carbon monoxide, ozone, and sulfur dioxide, and fine particles. These chemicals and particulates have been shown to cause arteries to constrict in healthy people, as well as raising blood pressure axnd disrupting the function of the vasculature; some research has suggested that oxidative stress on cells is involved, while others have pointed to an increase in inflammation or endothelial dysfunction.
A new study has indicated that the fine particulate matter in air pollution can trigger the production of bone marrow cells that promote inflammation. The research, which was reported in the European Heart Journal, suggests that these inflammatory cells cause inflammation in the arteries, and that there is no 'safe' level of air pollution exposure according to this air testing lab.
In this work, the researchers assessed 503 patients of Massachusetts General Hospital (MGH) who needed imaging tests to treat a variety of ailments, but none of them had cancer or heart disease. The average level of their particulate matter exposure was only estimated, but the researchers looked to air quality monitors that were closest to each volunteer's residence to obtain a value.
The retrospective study indicated that in a median period of 4.1 years, 40 of the participants had a major cardiovascular event like a heart attack. Those at highest risk were also exposed to the highest levels of fine particulate matter at their residence, and this elevated risk held true even when the investigators considered confounding factors like socioeconomics or other cardiovascular issues.
An analysis of the internal organs of these individuals revealed that they had higher activity levels in their bone marrow that indicate increased production of inflammatory cells and arterial inflammation.
"The pathway linking air pollution exposure to cardiovascular events through higher bone marrow activity and arterial inflammation accounted for 29 percent of the relationship between air pollution and cardiovascular disease events," said the co-first study author Shady Abohashem, M.D., a cardiovascular imaging fellow at MGH. "These findings implicate air pollution exposure as an underrecognized risk factor for cardiovascular disease and suggest therapeutic targets beyond pollution mitigation to lessen the cardiovascular impact of air pollution exposure."
Some people can't avoid air pollution, so therapies that act to reduce this increased inflammation could be especially beneficial to them, noted the co-first study author and MGH cardiologist Michael Osborne, M.D.
"Importantly, most of the population studied had air pollution exposures well below the unhealthy thresholds established by the World Health Organization, suggesting that no level of air pollution can truly be considered safe," he said.