Abstract
This study applied the analysis of variance (ANOVA) technique and Scott–Knott test to investigate the patterns associated with the variability of daily maximum ozone concentrations registered between 1996 and 2013 at 32 sites in the State of Sao Paulo, Brazil. The dataset was analyzed using the ANOVA three way test, arranged in a factorial design (4 × 2 × 32), with four replicates per treatment, followed by the Scott–Knott test. In the ANOVA and Scott–Knott test, the first factor (a) represented the seasons, the second factor (b) distinguished measurements taken on weekdays and weekends, and the third factor (c) distinguished each of the 32 sites. The ANOVA technique and Scott–Knott test produced significant results, showing a three-way interaction between the factors mentioned. We also identified that maximum ozone concentrations occurred generally during the spring, followed by the summer; also, greater values of ground level ozone were registered on weekends in most sites, especially in those influenced mainly by vehicular emissions. Furthermore, results suggest that vehicular emissions play an important role on triggering the weekend effect on ozone levels.
Highlights
São Paulo is the most populous state in Brazil
São Paulo has problems associated with air quality degradation: The Annual Air Quality Reports produced by CETESB (2016, 2017), based on the air quality standards established by State Decree 59.113 of 23rd April 2013, find that the average number of days per year in which ozone levels exceeded the 8-h standard of 140 μg m−3 was beyond 12, between 2004 and 2017 in MASP
Results from the Shapiro–Wilk test (α = 0.05) show that daily maximum ozone concentrations did not follow a normal distribution, which is a premise for carrying out analysis of variance (ANOVA)
Summary
São Paulo is the most populous state in Brazil. It has over 42 million people living in an area of around 249,000 square kilometers and over 13 million vehicles. According to the São Paulo State Environmental Protection Agency—CETESB (2017), in the MASP, vehicles are the main emission source of atmospheric pollutants such as carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOX). São Paulo has problems associated with air quality degradation: The Annual Air Quality Reports produced by CETESB (2016, 2017), based on the air quality standards established by State Decree 59.113 of 23rd April 2013, find that the average number of days per year in which ozone levels exceeded the 8-h standard of 140 μg m−3 was beyond 12, between 2004 and 2017 in MASP
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