Health & Medicine

Exposure to small particle pollution linked to heart-disease death

Data from about 8,000 women living in the Sacramento metropolitan area were used in a major study – released Wednesday – that linked death from heart disease to exposure to soot found in car exhaust, cooking smoke and diesel pollution.

The study, one of the most comprehensive to date, used data from the tracking of 100,000 middle-aged women in California between 2000 and 2007.

The study was conducted by the state’s Office of Environmental Health Hazard Assessment, as well as UC Davis and other institutions. It found an association between areas where there are high levels of fine particle pollution, and shorter life spans and a risk of heart disease death.

A growing body of evidence has shown that particle pollution is linked to increased risk of heart disease, lung cancer and asthma attacks.

California’s Air Resources Board estimates that 9,000 people die prematurely each year from exposure to particulate matter.

The OEHHA study is one of the first to look at the long-term effects of ultrafine particles – tiny particles that are a thousand times smaller than the width of a human hair, and tiny enough to pass through lung tissue and into the bloodstream. Most prior studies looked at much shorter exposures – usually a day or two – or at larger particles called fine particles.

The implication of the study is that those who live near freeways or active farms that use diesel machinery, and those who cook in or live near restaurants, may be at higher risk of breathing the particulate matter, said Mike Kleeman, professor of civil and environmental engineering at UC Davis.

The university provided long-term estimates of exposure the women had to ultrafine particles within a 2.5-mile area, said Kleeman.

The information was matched to health records in each area. According to the study, researchers found that women who lived in areas with more pollution from ultrafine particles suffered a higher death rate from heart disease.

“Where mortality should be highest is where there is the highest pollution – and those are places like Bakersfield and Central Valley population centers,” said Kleeman. “Sacramento has its own challenges with major freeways and wood smoke.

“If you look around a city like Sacramento there are two things emitting smoke right now – one are the fireplaces and the other is cooking operations that use an open flame where the fat drips to an open flame,” Kleeman added. “That produces these ultrafine particles.”

Kleeman said people who live near refineries and ports are also at risk of exposure to fine and ultrafine particle pollution.

The data on the women were culled from California teachers and administrators recruited from the California State Teachers Retirement System, said Bart Ostro, a researcher at OEHHA’s Air Pollution Epidemiology Section and lead author of the study, which appeared in the journal Environmental Health Perspectives.

Ostro said the data collected over the eight-year period was matched to information about particulate matter found in a 2.5-mile area where the women lived. Using that data, the study was able to eliminate risk factors that would cause death – such as smoking and drinking – as well as other factors such as socio-economic status.

“Then we looked at whether the women that lived where there were high levels of ultrafine particle exposure died earlier than those in areas where the levels were lower,” Ostro said. “We were able to rule out the possibility that the associations between exposure to ultrafine particles and death from heart attacks happened by chance.”

Ostro did not say what areas saw the highest mortality and said the scope of the study did not establish which women died from heart attacks.

“The data has not yet been analyzed to the point of estimating a specific number of deaths,” said Ostro.

But he said the researchers found that certain elements, such as copper, iron and elemental carbon – or soot – were strongly associated with death from heart attacks.

Kleeman said that more research will establish a closer link between particulate exposure and heart attack deaths.

“Air pollution is still an issue for California, and there are aspects of air pollution that we do not claim to understand yet,” said Kleeman. “The role of these ultrafine particles is something that we’re still actively investigating.”

Call The Bee’s Edward Ortiz, (916) 321-1071. Follow him on Twitter @edwardortiz.