We already know that particulate matter (PMs) is bad for your health because it can lodge in the lungs and cause both respiratory and heart problems. But most of the research on PMs has focused on outdoor air pollution involving car exhaust fumes. However, Indoor air pollution can be equally hazardous to health. A new study from researchers at Simon Fraser University, Burnaby, Canada, now reveals that the use of a HEPA filter improves heart health.

The researchers worked with 45 healthy adults in 25 homes in a small community in British Columbia where wood burning stoves are frequently used and are a common source of indoor pollution. A HEPA air purifier (or simply called 'HEPA filter') was installed in the main activity room of each home and a quieter HEPA filter was placed in the participant’s bedroom. The study lasted for two weeks; for one week, the HEPA filters were operated as normal, and for the other week the filters were removed. The participants were not aware of when their air was actually being filtered. An indoor air pollution sampler was placed in the main room.

Participants had levels of C-reactive protein (CRP) measured. CRP is a marker for inflammation and higher levels have been linked to heart disease risk. They also had their endothelial function measured with a fingertip device. The endothelium is the inner lining of the blood vessels and impaired endothelial functioning is another known indicator of heart disease risk.

The HEPA filter reduced the average PM concentration in the homes by 60% and of wood smoke particles by 75% (13 of the participants were using wood stoves in their homes during the study period). At the same time, CRP levels went down 33% and endothelial function improved by 10%.

‘Our results support the hypothesis that systemic inflammation and impaired endothelial function, both predictors of cardiovascular morbidity, can be favourably influenced by a reduction of particle concentration, and add to a growing body of evidence linking short-term exposure to particulate matter with a systemic inflammatory response,’ said lead investigator on this study, Dr Ryan Allen. ‘Reducing air pollution appears to provide health benefits even if the pollution levels are already relatively low.’

A HEPA filter is an easy and inexpensive way of cleaning up indoor air and this study suggests it can benefit your health. Wood burning stoves are not as common in use in the United Kingdom as they are in Canada. However, with energy prices rising and a growing interest in sustainable fuels, like wood, they could become more popular everywhere! This study shows they generate lots of PMs, so clean-burning models should be encouraged. And even if you never install a wood burning stove, a HEPA filter can still be useful – because this study also showed a clean up of PMs in the homes without the stoves.

Source: Allen et al An air filter intervention study of endothelial function among healthy adults in a woodsmoke-impacted community Respiratory and Critical Care Medicine online January 21 2011