Smoke impacts from agricultural burning in a rural Brazilian town.

Agricultural and silvicultural biomass burning is practiced in many undeveloped portions of the Amazon basin. In Rond nia, Brazil, such burning is restricted to a brief period in the dry season of August and September to minimize the duration of air quality impacts and to attempt to control escaped fires. During this period, much of the region and the communities within it experience significant exposure to smoke from agricultural and forest fires. In cooperation with Brazilian scientists of the University of Brasilia, the Brazilian Organization for Agricultural Research (EMBRAPA), and the Alternative to Slash and Burn Program coordinated by the International Center for Research in Agroforestry (ICRAF), ambient air quality was measured in Theobroma, a small town in Rond nia, during one week of the open burning period of 1995 to supplement available air quality data and to foster public awareness of the impacts of widespread fires. Personal sampling equipment was used to measure ambient levels of formaldehyde (HCHO), acrolein, CO, benzene, and respirable PM in outdoor air. The data obtained were compared with established Brazilian and U.S. ambient air quality guidelines. Ambient levels of respirable PM averaged 191 microg/m3, HCHO averaged 12.8 ppb, CO averaged 4.2 ppm, and benzene averaged 3.2 ppb. Almost all acrolein samples were less than the detection limit of 1 ppb. The results showed that the public can be exposed to relatively high levels of pollutants under the prescribed burning smoke management strategy of a two- to three-week prescription burning period, although this is an improvement over past years when burning was unregulated and continued through most of the dry season. The results also demonstrate the feasibility of using personal exposure monitoring equipment for low-cost surveys of ambient air quality in polluted regions.