Adding air purifiers into people’s households resulted in a 25% increase in heart rate variability among individuals with a diagnosis of chronic obstructive pulmonary disease (COPD), suggesting that indoor air purification systems may help lessen the global burden of cardiovascular diseases and COPD that are leading causes of death around the world.
This randomized control study is a subanalysis of data from the CLEAN AIR Trial and is the first US study to define an association between indoor air pollution and COPD. The results were published in American Journal of Respiratory and Critical Care Medicine.
“We’ve seen that air pollution in the home, where people spend a majority of their time, contributes to impairments in respiratory health. We hypothesized this pollution is a big driver of cardiovascular disease and cardiac events in people with COPD,” lead author Sarath Raju, MD, MPH, an assistant professor of medicine at the Johns Hopkins University School of Medicine, said in a statement.
Eighty-five participants with an average age of 65 who primarily lived in the Baltimore area were recruited for this 6-month study; the primary outcomes were heart rate variability gauged via standard deviation of normal to normal (SDNN) intervals and the root-mean square of successive differences (RMSSD) between normal-to-normal intervals.
A 2-fold increase in in household PM2.5 was associated with a decreases in SDNN (ß, –2.98%; 95% CI, -5.12 to -0.78) and RMSSD (ß, –4.57%; 95% CI, –10.1 to –1.60).
The greatest effects were observed in ultrafine particles (< 100 nm) (RMSSD: ß, –16.4%; 95% CI, –22.3 to –10.1) and among patients classfied as being obese.
All participants were former smokers with moderate to severe COPD.
Using air samples from within the patients’ homes, the researchers identified high levels of particulate matter (PM2.5). A healthy, level of PM2.5 is considered to be anything at or below 12 mcg/ft3. The researchers found an average of 13.8 mcg/ft3 of PM2.5 within the participant households.
The researchers gave 46 of these participants 2 portable air cleaners with HEPA and carbon filters to use at home, while the others received placebo air filters. Additionally, 317 heart rate variability assessments were gathered from these patients that would indicate lung and heart health, such as blood pressure and heart ultrasounds. The participants were also given heart rate monitors to wear 24 hours during each clinical testing period.
All 46 participants saw improvements in heart rate variability (25.2%; 95% CI, 2.99%-52.1%) compared with the placebo group, which saw no improvement. However, participants saw no improvement in SDNN (ß, 2.65%; 95% CI, –10.8 to 18.1) compared with the placebo group. Furthermore, 20 participants who used air purifiers 100% of the time at home had a 105.7% increase in heart rate variability associated with improved heart fitness.
The researchers also observed the effect of ultrafine particles in the home; such particles are so tiny they are able to travel to the deepest part of the lungs, and even into the bloodstream, and can have a deleterious effect on lung and heart health. From this, they found a correlation between ultrafine particles and poor health markers, such as lower heart rate variability, among 29 participants and their homes.
“These particles and other indoor air pollutants can cause systemic inflammation in susceptible patients, like those with COPD. Our study shows there’s a negative impact on cardiovascular health, as well,” said study author Meredith McCormack, MD, MHS, associate professor of medicine at John Hopkins University School of Medicine and director of the Bridging Research, Lung Health, and Environment Center, in the press release.
Although this was a small sample population study, the researchers believe it provides evidence of an association between indoor air pollution and COPD, in which the intervention may help reduce the cardiovascular risks, such as arrythmias, heart failure, stroke, and heart attack, that are often accompanied by COPD.
They also concluded that larger studies may be needed to confirm generalizability of their findings “across diverse populations and regions.”
Raju S, Woo H, Koehler K, et al. Indoor air pollution and impaired cardiac autonomic function in chronic obstructive pulmonary disease. American Journal of Respiratory and Critical Care Medicine. Published online October 26, 2022. doi:10.1164/rccm.202203-0523oc