Estudo da associação entre material particulado emitido em queimadas e doenças respiratórias no município de Manaus, AM

Abstract

The Amazon region has suffered in recent decades changes in the pattern of land use through the intense human occupation. These changes in land use are responsible for significant emissions aerosol particles to the atmosphere that, through the biomass burning, performing a series of direct and indirect effects on the climate and functioning of the Amazon ecosystem and the health of populations. Amazonia is characterized by very low aerosol concentrations during the wet season, with an average PM 10 of 10 μg/m3 for most of the region. In sharp contrast, during the dry season, concentrations up to about 400 μg/m3 are measured in the Southern and Eastern part of the Amazon basin. The health effect of exposure to such high aerosol loading is significant. Another important process occurring now in Amazonia is urbanization, with the city of Manaus growing fast in population, in the last decades. Currently has a population of 1.802.525 inhabitants, of which 99.4% lives in the in urban area. The objective of the study was to investigate the association of exposure to fine particulate matter (PM 2.5 ) emitted in biomass burning and hospitalizations in children under 9 years age by respiratory diseases (RDs), in Manaus, Amazonas, in the period 2002 to 2009. The data for PM 2.5 were estimated by using the MODIS sensor, with Aerosol Optical Depth (AOD) at 550 nm estimation. PM 2.5 were derived from MODIS AOD using relationships obtained for several sites in Amazonia were AERONET and MODIS AOD were obtained in parallel with PM2.5 measurements. Hospitalization data were obtained from Sistema Único de Saúde database (SUS – DATASUS). Statistical methods were used, with Pearson correlation and multiple linear regression between variables. Significant values were considered with a p-value < 0.05. It was observed that hospital admissions for respiratory diseases in children, in Manaus, may be more related to weather and humid air conditions, than from exposure to aerosols from biomass burning in the region. It was observed that the region of Manaus shows quite low PM 2.5 concentrations, when compared to the Southern Amazonian region. The annual average of PM 2.5 levels ranged from 14 to 17 μg/m3, just above the air quality standard recommended by World Health Organization (WHO) on 10 μg/m3 annually. Over the years, the months between August and November (dry period in the region; burning season), had the highest average levels of PM 2.5 , estimated between 18 to 23 μg/m3. The highest rates of hospitalization were observed during the rainy season, between March and June, and April was the month of highest average, with 2,51/1000 children. Manaus is located at a wet tropical climate area and presents almost always humid air in its weather normal conditions, with an average relative humidity always above 71%, during the study period. It was observed a positive association between hospital admissions and relative humidity (R=0,126; p-value=0,005), while the association between admissions and PM2.5 was negative and statistically significant (R=-0,168; p-valor=0,003). The R2 of the final model (Y = 18,87 – 1,66X 1 + 1,97X 2 – 0,21X 3 ) explained in about 5% of hospitalizations of RDs in children living in Manaus, considering the independent variables statistically significant (PM2.5, humidity and precipitation, respectively).