Indoor and outdoor pollution and human health in the Himalayas

Atmospheric composition change studies both at the Nepal Climate Observatory-Pyramid (NCO-P, 5079 m a.s.l.) in the high Khumbu valley, Southern Himalayas, and at Pakanajol, in the urban site of Kathmandu are carried out within ABC - UNEP program. As part of this long-term effort and to evaluate the effects on human health of indoor pollution, an interdisciplinary study was conducted during winter 2013 and 2014 in Chaurikharka, a village of the low Khumbu Valley in the Nepalese Himalayas, where people lives according to old traditional lifestyle. A major source of indoor air pollution in these settlements is due to smoke from open fires and cook stoves emitting high amounts of pollutants, including carbon monoxide. Among these indoor pollutants, equivalent black carbon (eqBC) particles are emitted at concentration about a factor of magnitude higher than the modern cook stoves. EqBC, considered an important Short-lived Climate Pollutant/Forcer, and other co-emitted species have a particularly large impact on public health because they make up a substantial part of both indoor and outdoor pollution. Indoor air quality in homes were monitored continuously for about 24 hours using a portable indoor air-quality system, developed at ISAC-CNR, able to monitor eqBC and particle size distribution (300 nm to 20 µm). In addition, in 2013 a portable detector was used to perform measurements of CO emitted by wood stoves when the fire was aglow and/or off. Moreover the outdoor air monitoring was carried out three times during the 2014 campaign for 24 hours each. Preliminary analyses showed that concentrations of eqBC higher than 10 µg/m3 are regularly observed during the morning and especially evening hours, when the braziers are burning wood or dung for cooking and heating, while night time concentrations are relatively low (0.7µg/m3). The CO concentrations during the burning of the brazier always exceeded 10 ppm and PM10 reached 300 µg/m3. In general, the houses with open stoves seem to be also less isolated: they show highest peak concentration at cooking time and the cleanest nighttime conditions. In connection with these measurements, 76 non-smokers (55 females, age 18-85) were subjected to the lung function test. Bronchial obstruction was present in 7.9% of the subjects (26.9% of subjects > 50 years). Early bronchial obstruction was present in 27.6% (55% of subjects > 50 years). These results are higher than expected in non-smoking subjects. 71 subjects (48 females) underwent also cardiovascular evaluation. The occurrence of hypertension was 21%, diabetes 7%, hypercholesterolemia (LDL>130mg/dl) 44%, obesity 10%, low HDL 49%, hypertriglyceridemia 24%. The endothelial function of the brachial artery, a method to assess early risk of atherosclerosis, was reduced (maximum percentage increase in diameter after reactive hyperemia: 4.07 ± 2.34 %). The environmental and health conditions monitored during this study in several houses in the Himalayan Khumbu Valley, indicate/establish that chronic exposure to indoor pollutiondefinitely impairs cardiorespiratory health in mountain dwellers.