Masks can cut air pollution risks

In a new study, researchers from Beijing have demonstrated that face masks can help protect those with coronary heart disease (CHD) from symptoms and health effects triggered by exposure to polluted air. Heart disease symptoms and blood pressure were both reduced when older men and women diagnosed with CHD wore the masks while walking in the city. The masks effectively filtered out almost all of the harmful fine and ultrafine particles released from cars and other traffic in the urban area. The results show that individual actions – in this case, wearing a special, high-efficiency mask – can alleviate some health effects linked to more serious cardiovascular problems in those susceptible to urban air pollution. In addition, the findings support previous research showing that breathing air pollution contributes to cardiovascular health effects. The results are most important for people in large, highly-polluted cities in developing countries where efforts to improve air quality are limited. 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. During the study, the researchers recruited 98 patients with coronary heart disease (CHD) in central Beijing, China, 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. Furthermore, the participants 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. The authors found that by wearing a face mask that filters out airborne particles, the symptoms of coronary heart disease that are exacerbated by exposure to air pollution were reduced. 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.

Environmental Health News, 5 April 2012 ; ;