The indoor air filtration devices used in this experiment were big and cumbersome. Homeowners can make do with smaller ones, though, and if they have a ventilation system, they only need to get a filter. (Photo: Gabriela Karottki, University of Copenhagen)

Bedroom air filtration improves elderly health

Tiny particles can affect the heart and lungs of elderly people. A new project shows that installing an air particle filter in the bedroom can improve health in polluted homes.

A particle filter can remove up to 50 percent of the particles that are believed to be harmful to the lungs, the heart and blood circulation.

So shows a new PhD project, carried out by Gabriela Karottki of the University of Copenhagen, Denmark.

The elderly people in the study who had the greatest reduction in the amount of particles in their bedroom experienced a significant improvement in microvascular function.

”We observed that the elderly people experienced significant improvements in microvascular function within two days, but generally, the amount of pollutant particles was not very high, and the effect may have been greater in more polluted homes,” says Karottki.

We observed that the elderly people experienced significant improvements in microvascular function within two days.

Gabriela Karottki

Overall, the researchers could not see any major health differences in the elderly people who lived in air-filtered homes. They nevertheless believe that large amounts of fine particles in the home can be harmful:

”We have a hypothesis that the fine particles affect the elasticity of the tiny blood vessels, so that the heart needs to pump harder. There is a greater risk of atherosclerosis and hypertension, especially in elderly people,” she says.

Drugs may mask the positive effect

In the participants who took vasoactive drugs, the presence of particle filters did not have an effect, perhaps because the drugs already have an effect on blood pressure and microvascular function.

However, Karottki is keen to point out that this does not mean that taking vasoactive drugs is an alternative to ventilating the home.

About the study

Forty-eight participants aged 51-81, spread over Danish 27 homes for the elderly, took part in the four-week study in which indoor air filtration systems were set up in the living room and bedrooms.

For two weeks the devices ran without filters, and for another two weeks the filters were on. Throughout the experiment, neither the participants nor the researchers knew whether or not a filter was being used.

The participants were mainly elderly people, since they are at risk of developing cardiovascular disease.

“The medicated patients are also affected by indoor air pollution, but the effect is masked by the medicine, which makes it more difficult for us to see it. Air pollution also does not only affect the blood vessels; the fine particles may also cause inflammation, damage to the lung function and may even damage our DNA.”

The researcher also points out that the elderly people who took vasoactive drugs did not have less atherosclerosis than the others in the study.

Greatest effect measured in the bedroom

A significant effect on microvascular function could be measured in the mornings after the participants had spent hours in their bedrooms. The same did not apply for the living room.

“One possible explanation may be that when the participants were in the bedroom, we could be pretty sure that they had stayed there over a longer period, and that fitted our measurements of microvascular function perfectly,” says co-author Steffen Loft, a professor at the Department of Public Health, Section of Occupational and Environmental Health, at the University of Copenhagen.

”In the daytime there is a limit to how much people stay in the living room; here, they tend to move around more inside and outside of the home.”

Even though the measurements established a positive effect on the participants’ blood vessels after having spent time in the bedroom, Loft believes that more and larger studies are needed before any clear conclusions can be made about the cardiovascular and respiratory effects of using indoor air filtration.

Particle filters are available everywhere

It is not difficult to get hold of a decent particle filter:

“The filtration device we used in our experiment was a bit of a monstrosity, but if people want a filtration device in their own home, there are plenty of them available commercially. This is, however, not something we would specifically recommend, as we still have a lot to learn about the positive effects,” says Loft.

The study was recently published in the journal Environmental Health.


Read the Danish version of this article at

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