ABSTRACT
In this paper, we analyze the variability of the ozone concentration over São Paulo Macrometropolis, as well the factors, which determined the tendency observed in the last two decades. Time series of hourly ozone concentrations measured at 16 automated stations from an air quality network from 1996 to 2017 were analyzed. The temporal variability of ozone concentrations exhibits well-defined daily and seasonal patterns. Ozone presents a significant positive correlation between the number of cases (thresholds of 100-160 µg m-3) and the fuel sales of gasohol and diesel. The ozone concentrations do not exhibit significant long-term trends, but some sites present positive trends that occurs in sites in the proximity of busy roads and negative trends that occurs in sites located in residential areas or next to trees. The effect of atmospheric process of transport and ozone formation was analyzed using a quantile regression model (QRM). This statistical model can deal with the nonlinearities that appear in the relationship of ozone and other variables and is applicable to time series with non-normal distribution. The resulting model explains 0.76% of the ozone concentration variability (with global coefficient of determination R1 = 0.76) providing a better representation than an ordinary least square regression model (with coefficient of determination R2 = 0.52); the effect of radiation and temperature are the most critical in determining the highest ozone quantiles.
Subject(s)
Air Pollution/analysis , Ozone/analysis , Brazil , Environmental Monitoring/methodsABSTRACT
RESUMO: Na Região Metropolitana do Rio de Janeiro, altos índices de concentrações de material particulado inalável (PM10) com violações dos limites estabelecidos pela Resolução CONAMA n0 03/90 são registrados rotineiramente. Analisando dados registrados entre 1998 e 2008, foram identificados 146 dias com concentrações acima dos valores estabelecidos. Nesses dias, foi possível verificar a influência da atuação do Anticiclone Subtropical do Atlântico Sul, a ausência de precipitação e a ocorrência de inversões térmicas na baixa troposfera, o que confirma a forte relação entre a ocorrência de altas concentrações de PM10 e as condições atmosféricas na região.
ABSTRACT: In the Metropolitan Area of Rio de Janeiro, high levels of particulate matter concentrations (PM10) with violations of the limits established by CONAMA Resolution 03/90 are routinely recorded. Analyzing data recorded between 1998 and 2008, 146 days with concentrations above these values were identified. In those days, it was possible to verify the influence of South Atlantic Subtropical Anticyclone, the lack of precipitation and temperature inversions in the lower troposphere, which confirm the strong relationship between high PM10 concentration and the atmospheric conditions in region.
