Masks can cut air pollution risks.
Langrish, JP, X Li, S Wang, MM Lee, GC Barnes, MR Miller, FR Cassee, NA Boon, K Donaldson, J Li, L Li, NL Mills, DE Newby and L Jiang. 2012. Reducing personal exposure to particulate air pollution improves cardiovascular health in patients with coronary heart disease. Environmental Health Perspectives http://dx.doi.org/10.1289/ehp.1103898.
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Vehicle exhaust, industry and other sources contribute to outdoor air pollution by releasing both gases and particles into the air.
Exposure to this mix of outdoor air pollutants is an important risk factor for cardiovascular disease and death (NIEHS). Estimates of 400,000 deaths occur each year due to polluted air in cities (United Nations Environment Programme 2006).
Studies show that even short-term exposures can cause changes in factors related to heart disease, such as an increased risk of heart attack (Mustafic et al. 2012). Continued exposure to air pollution often raises blood pressure, human studies show (Auchincloss et al. 2008). High blood pressure can contribute and lead to blocked arteries, heart attack, stroke and other deadly cardiovascular disease.
Studies consistently show cardiovascular effects – including heart attacks – are linked to breathing in the course, fine and ultrafine particles released during burning of fossil fuels and other materials.
Ninety-eight patients with coronary heart disease (CHD) in central Beijing, China, participated for two different 24-hour periods at least a week apart in spring 2009. On both days they completed a 2-hour walk on a designated city route, but on one of the days they wore a high-efficiency face mask, which filtered out 97 percent of the particles in the air.
Participants completed a questionnaire about mask comfort, perceived air pollution, and health symptoms – such as tiredness, nausea and headaches – at the start of each 24-hour study day, after the walk, and at the end of each study day. Automatic devices monitored blood pressure, heart rate variability (HRV) and faulty heart beats – called arrhythmia – for the 24-hour study duration.
HRV refers to the heart's ability to appropriately respond to changes in stimuli, such as respiratory patterns. High HRV is good because it means the heart is dynamic; low HRV indicates dampened responses. Arrhythmia refers to problematic heart beats – too fast, too slow or irregular – that usually result from faulty electrical signals within the heart.
The participants also wore a backpack with air monitoring instruments that recorded personal exposures during the study day. Ambient air monitoring stations supplied background air pollution measurements as well.
Researchers compared each participant's questionnaires and cardiovascular measurements on the day they wore the mask with the day they did not.
The main differences were found in measurements following the walk, though participants were monitored for longer. Blood pressure was significantly lower and heart rate variability (HRV) was higher when the face mask was used during the walk. Both indicate increased cardiovascular health.
Participants also found the masks were comfortable. They reported that pollution-related symptoms – things like headaches, tiredness and cough – lessened when they walked wearing the mask.
Because the study participants had CHD, the authors also examined if there were differences in blood pressure or heart rate variability in the 24-hour window around when the walks were conducted. No differences were identified.
Air pollution levels were consistently high during the study period, with fine and ultrafine particles making up almost all of the particulate matter measured. The size and composition of the particles suggested that most of the pollution came from combustion and traffic related sources.
Wearing a face mask that filters out airborne particles can reduce symptoms of coronary heart disease that are exacerbated by exposure to air pollution. Several different measures – including self-reported symptoms as well as physical indicators of cardiovascular health – reported by the researchers point to a similar conclusion.
The study suggests two things. First, personal actions to avoid or reduce exposures to particulate pollutants may be important and doable ways to control or alleviate symptoms that can lead to major coronary incidents. Second, the study also indicates that it is the particles that have direct effects on health, since the masks did not filter out the gases – the participants were still exposed to them while walking with the face covers – associated with air pollution.
A prior study from the same research group found similar effects on healthy adults. In that study, masks lowered blood pressure readings in healthy adults who wore the masks when walking the same amount of time as the patients with CHD in this study.
Overall, interventions and large-scale attempts to improve air quality have great public health importance. In addition, simple personal solutions may also benefit and improve health for people feeling the effects of polluted air. This may be especially important in large, highly polluted urban areas where there is little effort to control emissions.
Air pollution and cardiovascular disease. National Institute of Environmental Health Sciences (NIEHS). Online March 27, 2012.
Auchincloss,AH, AV Roux, JT Dvonch, PL Brown, RG Barr, ML Daviglus, DC Goff, Jr., JD Kaufman and MS O’Neill. 2008. Associations between recent exposure to ambient fine particulate matter and blood pressure in the multi-ethnic study of atherosclerosis (MESA). Environmental Health Perspectives 116(4):486-491.
Mustafic´, H, P Jabre, C Caussin, MH Murad, S Escolano, M Tafflet, M-C Perier, E Marijon, D Vernerey, J-P Empana and X Jouven. 2012. Main air pollutants and myocardial infarction. A systematic review and meta-analysis. Journal of the American Medical Association 307(7):713-721.
O'Connor, A. 2012. Air pollution linked to heart and brain risks. New York Times, Feb 15.
United Nations Environment Programme. 2006. GEO Year Book 2006. An overview of our changing environment. Progress Press Ltd. Malta.
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Air pollution and heart disease