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

Abstract

To assess the cardiovascular benefits of protecting against particulate air pollution and noise, we conducted a randomized crossover study with 40 young healthy college students from March to May 2017 in the underground subway, Beijing. Participants each received 4 treatments (no intervention phase [NIP], respirator intervention phase [RIP], headphone intervention phase [HIP], respirator plus headphone intervention phase [RHIP]) in a randomized order during 4 different study periods with 2-week washout intervals. We measured personal exposure to particulate matter (PM), noise and electrocardiogram (ECG) parameters (heart rate variability (HRV), heart rate (HR) and ST segment changes), ambulatory blood pressure (BP) continuously for 4 hours to investigate the cardiovascular effects. Compared with NIP, most of the HRV parameters increased, especially high frequency (HF) [21.1% (95% CI: 15.7%, 26.9%), 18.2% (95% CI: 12.8%, 23.9%), and 35.5% (95% CI: 29.3%, 42.0%) in RIP, HIP, and RHIP, respectively], whereas ST segment elevation and HR decreased for all 3 modes of interventions. However, no significant differences were observed in BP among the 4 treatments. In summary, short-term wearing of a respirator and/or headphone may be an effective way to minimize cardiovascular risk induced by air pollution in the subway by improving autonomic nervous function.

Reduction of environmental pollutants for prevention of cardiovascular disease: it’s time to act

“…Heart rate variability indices were, however, variably improved with either intervention. 37 Face masks and procedural masks (e.g. surgical masks) are widely available but are not effective in filtering PM 2.5 , especially if poorly fitting or worn during high activity, 38 and therefore cannot be recommended for widespread usage if N95 respirators are available.…”

The effect of particulate matter reduction by indoor air filter use on respiratory symptoms and lung function: A systemic review and meta-analysis

“…During the study period, the concentration of PM 2.5 was 86-140 ug/m 3 in Beijing. Other studies also support the cardiovascular effects of facial mask use to avoid PM, including decreased systolic blood pressure, increased heart rate variability, and reduced ST segment depression (27,36,37), even when considering the confounding effect of traffic noise (38).…”

Air Pollution and Noncommunicable Diseases

“…109 The beneficial effects of personal respirators extended to other cardiovascular markers and were almost immediate and lasted during the exposure time. 110 Air purifiers also reduce PM. Air purification for just 48 h significantly decreased PM 2.5 and reduced circulating inflammatory and thrombogenic biomarkers as well as systolic and diastolic BPs.…”