Cardiovascular Benefits of Wearing Particulate-Filtering Respirators: A Randomized Crossover Trial

Abstract

Background:Practical approaches to protect individuals from ambient particulate matter (PM) are urgently needed in developing countries. Evidence on the health benefits of wearing particulate-filtering respirators is limited.Objectives:We evaluated the short-term cardiovascular health effects of wearing respirators in China.Methods:A randomized crossover trial was performed in 24 healthy young adults in Shanghai, China in 2014. The subjects were randomized into two groups and wore particulate-filtering respirators for 48 hr alternating with a 3-week washout interval. Heart rate variability (HRV) and ambulatory blood pressure (BP) were continuously monitored during the 2nd 24 hr in each intervention. Circulating biomarkers were measured at the end of each intervention. Linear mixed-effect models were applied to evaluate the effects of wearing respirators on health outcomes.Results:During the intervention periods, the mean daily average concentration of PM with an aerodynamic diameter < 2.5 μm (PM2.5) was 74.2 μg/m3. Compared with the absence of respirators, wearing respirators was associated with a decrease of 2.7 mmHg [95% confidence interval (CI): 0.1, 5.2 mmHg] in systolic BP and increases of HRV parameters, including 12.5% (95% CI: 3.8%, 21.2%) in high frequency (HF) power, 10.9% (95% CI: 1.8%, 20.0%) in the root mean square of the successive differences, and 22.1% (95% CI: 3.6%, 40.7%) in the percentage of normal RR intervals with duration > 50 msec different from the previous normal RR interval (pNN50). The presence of respirators was also associated with a decrease of 7.8% (95% CI: 3.5%, 12.1%) in the ratio of low frequency (LF)/HF power.Conclusions:Short-term wearing of particulate-filtering respirators may produce cardiovascular benefits by improving autonomic nervous function and reducing BP.Citation:Shi J, Lin Z, Chen R, Wang C, Yang C, Cai J, Lin J, Xu X, Ross JA, Zhao Z, Kan H. 2017. Cardiovascular benefits of wearing particulate-filtering respirators: a randomized crossover trial. Environ Health Perspect 125:175–180; http://dx.doi.org/10.1289/EHP73

Cardiovascular benefits of reducing personal exposure to traffic-related noise and particulate air pollution: A randomized crossover study in the Beijing subway system

“…We observed altered HRV parameters and HR after short‐term reductions in exposure to PM, consistent with 2 previous respirator intervention studies . In addition, we found significant elevations in HF power, rMSSD and pNN50, and decreases in LF/HF and HR, all of which highlight a predominance of parasympathetic tone.…”

“…We observed altered HRV parameters and HR after short-term reductions in exposure to PM, consistent with 2 previous respirator intervention studies. 19,20 In addition, we found significant elevations in HF power, rMSSD and pNN50, and decreases in LF/HF and HR, all of which highlight a predominance of parasympathetic tone. In accordance with our study, a previous panel study found that reduced air pollution levels due to intensive air pollution control measures during the Olympic Games (including vehicle restriction and closure of air polluting factories) improved HRV indices in healthy taxi drivers in Beijing.…”

“…While the findings related to the association between long‐term PM exposure and BP are relatively consistent, the effects of short‐term PM exposure on BP appear more variable. Two intervention trials found that 48 h reduced PM exposure was associated with decreased SBP, whereas two other similar intervention studies failed to find such changes . Surprisingly, a few studies also reported that reduced PM exposure was associated with increased DBP .…”

The Forest and the Trees: How Population-Level Health Protections Sometimes Fail the Individual

“…The better masks can have benefits, even for healthy individuals 9 . In a recent study evaluating the short-term cardiovascular health effects of wearing particulate respirators, researchers from Fudan University in Shanghai and Texas A&M University’s School of Public Health measured heart rate variability and blood pressure in 24 healthy young adults with and without masks.…”

“Stressed” About Air Pollution

“…5,13 Indeed, findings by this same group of investigators recently demonstrated favorable changes in blood pressure and other biomarkers when healthy young adults in Shanghai wore N95 respirators. 14 Given the danger posed by air pollution and the short-term benefits of personal-protection strategies (indoor air filtration and N95 facemasks) on improving surrogate health end points, why have these relatively inexpensive practical approaches not been promoted to the public at-large by scientific and health agencies? 3,4 The answer is that there have been no large-scale randomized controlled outcome studies with hard cardiovascular end points (eg, acute coronary syndromes, strokes, heart failure) to conclusively support the basis for any such formal recommendations in any population.…”