Understanding Ozone Concentrations During Weekdays and Weekends in the Urban Area of the City of Rio de Janeiro

• Autor(a) principal: Martins,Eduardo M.
• Data de Publicação: 2015
• Outros Autores: Nunes,Anna C. L., Corrêa,Sergio
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532015001001967
• topic: ozone; weekend; weekday; NOx; VOC; modelling

In different cities around the world, higher ozone concentrations are observed during weekends for various reasons. This study aims to determine the causes of this effect in the city of Rio de Janeiro based on measurements obtained at three automatic air quality monitoring stations in the Bangu, Campo Grande and Irajá neighborhoods between 2012 and 2013. Variations in the solar radiation and hourly carbon monoxide, nitrogen oxides, non-methane hydrocarbons, ozone and particulate matter concentrations were determined. The Bangu station showed the lowest ozone concentration differences between the weekdays and weekends (8.9%) and recorded the highest ozone concentrations and largest number of exceedances. The low ozone consumption by nitrogen oxide resulted in the high ozone concentrations at the Bangu station. In addition, the volatile organic compounds (VOC)/nitrogen oxides (NOx) ratio for this station was evaluated for each day of the week between 6 and 9 AM, and the observed VOC/NOx ratios were higher at the Campo Grande and Irajá stations. We concluded that the weekend effect occurred at all three of the evaluated stations, with greater intensity at the Campo Grande and Irajá stations. The main cause of this weekend effect is the greater reductions in NO emissions over the weekends, which increase the VOC/NOx ratio.