The Effects of Facemasks on Airway Inflammation and Endothelial Dysfunction in Healthy Young Adults: A Double-Blind, Randomized, Controlled Crossover Study

Abstract

Background: Facemasks are increasingly worn during air pollution episodes in China, but their protective effects are poorly understood. We aimed to evaluate the filtration efficiencies of N95 facemasks and the cardiopulmonary benefits associated with wearing facemasks during episodes of pollution. Results: We measured the filtration efficiencies of particles in ambient air of six types of N95 facemasks with a manikin headform. The most effective one was used in a double-blind, randomized, controlled crossover study, involving 15 healthy young adults, conducted during 2 days of severe pollution in Beijing, China. Subjects were asked to walk along a busy-traffic road for 2 h wearing authentic or sham N95 facemasks. Clinical tests were performed four times to determine changes in the levels of biomarkers of airway inflammation, endothelial dysfunction, and oxidative stress within 24 h after exposure. The facemasks removed 48-75% of number concentrations of ambient air particles between 5.6 and 560 nm in diameter. After adjustments for multiple comparison, the exhaled nitric oxide level and the levels of interleukin-1α, interleukin-1β, and interleukin-6 in exhaled breath condensate increased significantly in all subjects; however, the increases in those wearing authentic facemasks were statistically significantly lower than in the sham group. No significant between-group difference was evident in the urinary creatinine-corrected malondialdehyde level. In arterial stiffness indicators, the ejection duration of subjects wearing authentic facemasks was higher after exposure compared to the sham group; no significant between-group difference was found in augmentation pressure or the augmentation index. Conclusions: In young healthy adults, N95 facemasks partially reduced acute particle-associated airway inflammation, but neither systemic oxidative stress nor endothelial dysfunction improved significantly. The clinical significance of these findings long-term remains to be determined. Trial registration: The trial registration number (TRN) for this study is ChiCTR1800016099, which was retrospectively registered on May 11, 2018.

Air pollution and cardiovascular disease: car sick

“…42 Indeed, it is encouraging that a number of studies have shown that reduction of personal exposure to urban PM through use of facemasks has been accompanied by improvements in cardiovascular parameters. 42,[56][57][58]242 Indoor air purifiers also appear to have beneficial effects in this regard, especially in cities with high levels of pollution. 42,243 The long-term consequences of these short-term benefits need to be established.…”

Qualitative fitting characteristics of filtering face-piece respirators on Iranian people

“…There are various studies were performed regarding the respirators' performance [2][3][4][5][6][7][8][9][10][11]. For instance, Mueller et al concluded that both filter efficiency and proper respirator fitting into the face are vital to provide the optimal protection [8,12].…”

Personal strategies to minimise effects of air pollution on respiratory health: advice for providers, patients and the public

“…Masks can trap warm, moist air, leading to rashes or overheating [21] and potentially pathogen retention [22]. Additionally, respirators may increase resistance to breathing, which may contribute to potential cardiovascular effects [16,23,24]. Cloth masks, which are inexpensive and used commonly in underdeveloped regions, remove only 15% of particles of size typical of diesel engine emissions [25] and are far inferior to protection against fine particles than facemasks rated as N95 (defined as filtering ⩾95% of 0.3 µm particles under test conditions) [13,14,25].…”

“…Evidence that N95 facemask use has an impact on cardiopulmonary health is limited. Short-term (2 h) use reduced particle-associated airway inflammation [24] and improved measures of autonomic nervous function [8,28] and blood pressure [8] versus wearing no facemask. N95 facemask use reduced the decline in lung function associated with air pollution among traffic police in Nepal [27].…”

“…N95 facemask use reduced the decline in lung function associated with air pollution among traffic police in Nepal [27]. In a small, randomised, crossover study, powered air-purifying respirators with high-efficiency particulate air (HEPA) filters (likely impractical for most users) reduced exhaled markers of oxidative stress in individuals in cars within heavy traffic versus without HEPA filters [29], although another study using a standard N95 facemask showed no protection from systemic oxidative stress [24].…”