Academic journal article Environmental Health Perspectives

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

Academic journal article Environmental Health Perspectives

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

Article excerpt


Cardiovascular health hazards are among the primary health risks associated with air pollution exposure (Donaldson et al. 2013). A number of population-based epidemiological studies have demonstrated that short-term exposure to air particulate matter (PM) is associated with reduced heart rate variability (HRV) (Baccarelli et al. 2008; Ren et al. 2010) and increased blood pressure (Hampel et al. 2011) and inflammation levels (Liu et al. 2009), all of which can act as indicators for potential adverse cardiovascular health effects. PM with an aerodynamic diameter < 2.5 [micro]m ([PM.sub.2.5]) is particularly associated with cardiovascular damage and can act as a stimulus to trigger local cytokine production and systemic inflammation (Schins et al. 2004).

In developing countries where the population size is large and air pollution levels are high, the disease burden associated with [PM.sub.2.5] is more severe than that in North America and Europe. The Global Burden of Disease (GBD) study estimated that ambient PM ranked fourth among all risk factors in China in 2010, contributing nearly 8% of the total disability-adjusted life years (Yang et al. 2013). Given that it is not easy to cut the emission of air pollutants in a short time in developing countries, approaches that can reduce individual exposure are considered to be practical and cost-effective in protecting the public from ambient PM. These approaches are urgently needed in highly polluted countries such as China and India. Previous studies have reported the health benefits associated with the use of indoor air purifiers and oral supplements (Chen et al. 2015a; Romieu et al. 2008). Wearing particulate-filtering respirators, one of the most convenient and affordable protective measures, is becoming increasingly popular in China, particularly in outdoor environments. However, evidence of their health benefits is limited (Langrish et al. 2009, 2012).

Therefore, we designed a randomized controlled crossover trial to evaluate the potential cardiovascular benefits associated with wearing a particulate-filtering respirator in a group of healthy young adults in Shanghai, China. We examined blood pressure (BP), HRV, and circulating biomarkers of important pathways by which PM exposure leads to adverse cardiovascular outcomes (Brook et al. 2010).

Materials and Methods

Study Design and Participants

We conducted a randomized crossover trial in a group of healthy college students at Fudan University, Shanghai, China, during the period from 21 March to 13 April 2014. The entire study was completed within 1 month to avoid potential confounders resulting from long-term and seasonal trends of health outcomes.

Initially, we recruited 30 students with no history of tobacco smoking (never smokers) or alcohol addiction, no clinically diagnosed chronic cardiopulmonary diseases (including asthma, rhinitis, and others) and no recent infections. Because all participants lived in campus dormitory rooms (a typical dormitory room is shared by four or six persons) and studied within the campus, they were seldom exposed to environmental tobacco smoke because smoking was banned in all public places on the campus.

The participants were equally randomized into two groups and wore particulate-filtering respirators for 48 hr alternating with a 3-week washout interval. Specifically, in the first intervention period, one group wore the designated high-efficiency particulate-filtering respirators for 48 hr as the intervention group, while the other group behaved as usual (the control group). After a 3-week wash-out interval, the two groups exchanged roles and completed the second intervention period. HRV and ambulatory BP were continuously monitored during the second 24 hr of each intervention. Blood samples were collected at the end of each intervention period at approximately the same time to measure circulating biomarkers of inflammation, vasoconstriction, and coagulation. …

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