A six-month study by researchers at Johns Hopkins Medicine finds that using portable home air purifiers can improve certain markers of cardiovascular health in people with chronic obstructive pulmonary disease, or COPD. People with COPD often suffer from shortness of breath, chest tightness and chronic cough. Cardiovascular diseases such as arrhythmias, heart failure, strokes and heart attacks commonly accompany COPD, and COPD and cardiovascular disease are the leading causes of death worldwide, according to the World Health Organization. health.
The new research, described online October 26 in the American Journal of Respiratory and Critical Care Medicine, is a sub-study of a larger project led by Johns Hopkins, the CLEAN AIR study. The CLEAN AIR study, which investigated the effects of indoor air pollution on COPD, found that people with COPD showed improvement in symptoms after using portable air purifiers indoors .
“We found that air pollution in the home, where people spend the majority of their time, contributes to respiratory health issues. We hypothesized that this pollution is an important factor in cardiovascular disease and cardiac events in people with COPD,” says author Sarath Raju, MD, MPH, assistant professor of medicine specializing in obstructive pulmonary disease at the Johns Hopkins University School of Medicine.
The researchers recruited 85 men and women from the original CLEAN AIR study, who were adults (mean age 65) with COPD. The participants lived primarily in the Baltimore area.
First, the researchers had trained technicians take air samples of indoor particulate matter of varying sizes from the participants’ homes. These indoor air pollutants are made up of things like mold and pet dander. One of the smallest types of particles, PM 2.5 – smaller than the diameter of a human hair – can harm respiratory and heart health by entering the bloodstream through the lungs and causing inflammation. The indoor PM 2.5 level must remain at or below 12 micrograms per cubic foot for the air to be considered safe to breathe. Participants’ homes had an average of 13.8 micrograms per cubic foot of PM 2.5.
Next, 46 randomized participants were given 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 the filters removed.
Researchers tracked and measured several indicators of lung and heart health over the one-week, three-month, and six-month periods of the study using standard clinical tests, such as blood pressure and heart ultrasounds (echocardiograms). Additionally, participants wore heart rate monitors for 24 hours during each clinical test period, to assess heart rate variability.
At the end of the experiment, all 46 participants with active HEPA and carbon filters showed improved markers of heart health, specifically a 25% increase in heart rate variability. Participants without 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 consecutive heartbeats. A healthy heart constantly adjusts its rate to meet the physical demands of the body and as such its heart rate is more variable.
Among the 20 participants who used the air purifiers with active filters 100% of the time at home, there was also a 105.7% increase in a measure of heart health variability called the root mean square of successive differences between normal heartbeats, or RMSSD, which is associated with better 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, are able to travel to the deepest part of the lungs when inhaled, and can even pass through the bloodstream.
In their assessment of 29 participants and their homes, the researchers found a correlation between increased ultrafine particles and lower markers of heart health, such as lower heart rate variability. The team says more research needs to be done in this area.
“Ultrafine particles may be the most potent particles in terms of health consequences,” says Meredith McCormack, MD, MHS, study author, associate professor of medicine at Johns Hopkins University School of Medicine and director of BREATHE Center (Bridging Research, Lung Health and the Environment). “These particles and other indoor air pollutants can cause systemic inflammation in susceptible patients like those with COPD. Our study shows that there is also a negative impact on cardiovascular health.”
“In the future, air purifiers might be something to recommend to patients along with medications, but they might also be part of a larger discussion about the importance of the home environment,” Raju says.
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 supported by NIH/NIEHS grants (R01ES022607, R21ES025840, and F32ES029786), an NHLBI grant (K12HL143957 and K23HL164151), and a catalyst award from Johns Hopkins University.