Connect with us

Hi, what are you looking for?


Are air purifiers contributing to asthma?

Chinese researchers have undertaken an assessment of stand-alone portable air purifiers. These types of devices are being used on a wider basis to address dust inside homes and especially in areas where outdoor pollution levels are high. While there are different views about the effectivness of such devices, the use of fixed or portable units has become a popular means of controlling individual inhalation exposure. Many such devices use high efficiency particulate air (HEPA) fiters.

However, there are concerns in general about exposure to bacterial endotoxins and the role these cellular fragments play in relation to respiratory inhalation health (triggering conditions such as asthma, especially as endotoxin exacerbates asthma). For example, a Japanese study published in 2020 found that endotoxin in outdoor air is significantly associated with an increased risk of asthma exacerbation in children.

Of concern to the researchers from Beihang University, Beijing, is the impact of indoor air purifiers. The researchers looked at changes in endotoxin levels in indoor air before and after purification by a portable air purifying devices.

The results showed an increase in endotoxins after a previously used air purifier was turned on in order to clean indoor air. This led the researchers to conlude that the use of air purifier devices could lead to increased endotoxin deposition in airways when used in the home. The particular physioogical area of concern was the alveolar region.

In terms of why this should be the case, the scientists demonstrated that endotoxin concentrations on the HEPA filters were strongly correlated with the free DNA concentrations on the HEPA filters. This correlation indicates that bacteria disrupted by the HEPA filter (which is designed to capture bacteria and pollutants like pollen) led to the release of free bacterial DNA and endotoxins.

Hence, HEPA filters are a source of indoor airborne endotoxins and could have an association with different respiratory diseases.

The research has been published in the journal Environment International. The research paper is titled “Indoor air filtration could lead to increased airborne endotoxin levels.”

Written By

Dr. Tim Sandle is Digital Journal's Editor-at-Large for science news. Tim specializes in science, technology, environmental, and health journalism. He is additionally a practising microbiologist; and an author. He is also interested in history, politics and current affairs.

You may also like:


Many people, meaning millions, are truly outraged and offended by billionaires going into space on joyrides.

Tech & Science

The global dominance of tech giants serves as a convenient online chokepoint for authoritarian governments to crack down on dissent or rig elections.


Moving forward on the campaign trail. Source - Justin Trudeau @JustinTrudeau Officiel du gouvernement - Canada.Justin Trudeau is facing harsh criticism from political rivals...


FIFA Women's World Cup 2019 Final - The US team receiving their champion medals. Image - Howcheng, CC SA 4.0. The US Soccer Federation...