Pearce et al. (2009) studied the use of biofuels for household energy in Cusco, determining that the combustion of these fuels resulted in potentially dangerous levels of PM2.5 and CO emissions. Combined with the hypoxic stress of high-altitude living, this is a very real threat to human health. The study concluded that the levels of PM2.5 emissions present in kitchens were 4.4 times higher than those in secondary rooms and 9.4 times higher than those in outside entryways. Similarly, the CO concentrations were highest in kitchens, with concentrations averaging 4.8 times more than secondary rooms and 3.3 times more than outdoor entryways. They found that the highest levels of CO and PM2.5 emissions occurred with the combustion of dung, followed by wood, kerosene, and gas, respectively.—Christina Mainero
Pearce, J., Aguilar-Villalobos, M., Rathbun, S., Naeher, L., 2009. Residential exposures to PM2.5 and CO in Cusco, a high altitue city in the Peruvian Andes: A Pilot Survey. Archives of Environmental and Occupational Health 64, 278-282.
The goal of this study by Pearce et al. was to measure the average indoor and outdoor CO and PM2.5 emissions at 41 residences in Cusco during the preparation of meals in the morning, afternoon, and evening. Measurements of CO and PM2.5 emissions were taken at breathing level to mimic human exposure to these pollutants. The measurements were taken in three different locations in each residence—the kitchen, the room designated as the second most used room, and the front entryway outside each home. To minimize any discrepancies, the concentration levels of both CO and PM2.5 were collected simultaneously.
Statistical analyses of the data on PM2.5 emissions demonstrated that emissions caused by the combustion of wood are significantly higher than those caused by kerosene, while those from dung are significantly higher than those caused by gas. Furthermore, in secondary rooms, PM2.5 emissions from wood combustion were significantly higher than those from gas. Similarly, wood emissions of CO in kitchens were significantly higher than gas emissions. Overall, the median CO and PM2.5 emissions were highest for the combustion of dung, followed by wood, kerosene, and gas, respectively. Kitchens, where the food preparation occurred, tended to have the highest concentrations of CO and PM2.5, followed by the secondary rooms and then the outdoor entryways. Furthermore, the general trend seemed to show that the greatest concentration of pollutant emissions occurred in the morning, which the authors suggested was due to the fact that large meals tend to be prepared in the morning and simply reheated throughout the rest of the day in Cusco.
However, Pearce et al. noted that there were several limitations in their study, including the small sample size, the shortness of the data collection period, the lack of an even distribution of measurements across the different fuel types, and the fact that the measurements of pollutant concentrations did not actually measure the number of human exposures to CO and PM2.5 emissions. Despite these limitations, this study is interesting in that it notes the potential dangers of the combustion of biofuels and fuels in the preparation of food, particularly in developing countries, such as Peru.