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.
Highlights
Air pollution is recognized to be an important problem that is affecting public health and responsible for a variety of health effects (Künzli et al 2000; Landrigan et al 2018; Leiva et al 2013; Levy et al 2005; Monn 2001; Pope et al 2002; van Zelm et al 2008; Weschler 2006; WHO 2016).Tropospheric ozone (O3) is one of the air pollutants with major concern globally
The presence of clouds contributes to modifying ozone production chain, reducing the available solar radiation, which drives the chemistry of the atmosphere by dissociating a number of molecules in fragments that are often highly reactive and by heterogeneous reactions, which droplets and ozone precursors are removed by wet deposition
The establishment of air quality standards must be based on scientific knowledge in order to provide a foundation for protecting people health from exposition of high ozone
Summary
Air pollution is recognized to be an important problem that is affecting public health and responsible for a variety of health effects (Künzli et al 2000; Landrigan et al 2018; Leiva et al 2013; Levy et al 2005; Monn 2001; Pope et al 2002; van Zelm et al 2008; Weschler 2006; WHO 2016).Tropospheric ozone (O3) is one of the air pollutants with major concern globally. Ozone is a secondary pollutant, which means that it is not directly released into the atmosphere, but formed by a chain of photochemical reactions that depend on the availability of Environ Sci Pollut Res (2019) 26:31699–31716 incoming solar radiation and on the concentrations of many primary pollutants (directly released into the atmosphere) such as volatile organic compounds (VOC) and nitrogen oxides (NOX). The ozone is directly affected by many physical processes of transport (turbulent mix, transport from upper levels of the atmosphere, advection by the mean wind and dry deposition). The presence of clouds contributes to modifying ozone production chain, reducing the available solar radiation, which drives the chemistry of the atmosphere by dissociating a number of molecules in fragments that are often highly reactive and by heterogeneous reactions, which droplets and ozone precursors are removed by wet deposition
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