A six-month study led by researchers at Johns Hopkins Medicine concludes that using portable home air purifiers may improve some markers of cardiovascular health in people with chronic obstructive pulmonary disease, or COPD. People with COPD often experience shortness of breath, chest tightness, and chronic cough. Cardiovascular diseases such as arrhythmias, heart failure, stroke, and heart attack usually accompany COPD, and according to the World Health Organization, both COPD and cardiovascular disease are the leading causes of death worldwide.
The new research, described online Oct. 26 in the American Journal of Respiratory and Critical Care Medicine, is a secondary study of a larger Johns Hopkins-led project, the CLEAN AIR study. The CLEAN AIR study, which examined the effects of indoor air pollution on COPD, found that people with COPD experienced improved symptoms after using portable indoor air purifiers.
“We have seen that air pollution in the home, where people spend most of their time, contributes to respiratory health disorders. We hypothesized that this pollution is a major driver of cardiovascular disease and cardiac events in humans with COPD,” says lead author Sarath Raju, MD, MPH, an assistant professor of medicine specializing in obstructive pulmonary disease at Johns Hopkins University School of Medicine.
Researchers recruited 85 men and women from the original CLEAN AIR study, who were adults (mean age 65 years) with COPD. Most of the participants lived in the Baltimore area.
First, researchers had trained technicians take air samples of indoor particulate matter of various sizes from participants’ homes. These indoor air pollutants are composed of things like mold and pet dander. One of the smallest types of particulate matter, PM 2.5 – smaller than the diameter of a human hair – can harm respiratory and heart health by infiltrating the bloodstream through the lungs and causing inflammation. Indoor PM2.5 levels must remain at or below 12 micrograms per cubic foot for the air to be considered healthy to breathe. Participants’ homes averaged 13.8 micrograms per cubic foot of PM2.5.
Next, 46 randomized participants received two portable air purifiers with HEPA and carbon filters to use at home; the other participants were given placebo air purifiers that circulated air but had their filters removed.
Researchers tracked and measured various indicators of lung and heart health during the one-week, three-month, and six-month periods of the study using standard clinical tests, such as blood pressure and ultrasound of the heart (echocardiograms). In addition, during each clinical trial period, participants wore heart rate monitors for 24 hours to assess heart rate variability.
At the end of the experiment, all 46 participants with active HEPA and carbon filters had improved markers of heart health, specifically a 25% increase in heart rate variability. Participants without the active filters saw no increase.
Heart rate variability, or HRV, is a common measure of heart health calculated using other statistical variables, such as the standard deviation between heartbeats. HRV consists of changes in the time intervals between successive heartbeats. A healthy heart is constantly adjusting its rate to meet the physical demands of the body and as such has a higher heart rate variability.
Among the 20 participants who used the air purifiers with active filters 100% of the time while at home, there was also a 105.7% increase in a measure of heart health variability, the root-mean-square of sequential differences between normal heart beats, or RMSSD, which is associated with improved heart fitness.
The team also looked at the effects of ultrafine particles in homes. These particles, smaller than a thousandth of a millimeter or a micron, can travel to the deepest part of the lungs when inhaled and even enter the bloodstream.
In their evaluation of 29 participants and their homes, the researchers found an association between an increase in ultrafine particles and worse heart health markers, such as lower heart rate variability. The team says more research needs to be done in this area.
“Ultrafine particles are perhaps the most powerful particles in terms of health impacts,” said study author Meredith McCormack, MD, MHS, associate professor of medicine at Johns Hopkins University School of Medicine and director of the BREATHE Center (Bridging Research, Lung Health and the Environment). “These particulates and other indoor air pollutants can cause systemic inflammation in susceptible patients such as COPD patients. Our research shows there is also a negative impact on cardiovascular health.”
“In the future, air purifiers could be something to recommend to patients along with medications, but they could also be part of a larger discussion about the importance of home environments,” says Raju.
Other researchers involved in the study include Han Woo, Ashraf Fawzy, Chen Liu, Nirupama Putcha, Aparna Balasubramanian, Cheng Ting Lin, Ronald Berger, and Nadia Hansel of Johns Hopkins University School of Medicine; Kirsten Koehler and Roger Peng of the Johns Hopkins Bloomberg School of Public Health; Chantel Lemoine of the University of Pittsburgh Medical Center; and Jennifer Wineke of the University of Maryland Medical Center.
This research was funded by NIH/NIEHS grants (R01ES022607, R21ES025840, and F32ES029786), an NHLBI grant (K12HL143957 and K23HL164151), and a Johns Hopkins University Catalyst Award.