Half Century Monitoring Air Pollution in a Megacity: a Case Study of Rio de Janeiro

The population increase has led to the rise of megacities that generate high levels of pollutants. To examine the temporal and spatial trends, the concentration data of total suspended particles (TSP) and coarse particles (particulate matter (PM)10) from the Rio de Janeiro State Environmental Institute (INEA) collected between 1968 and 2013 were used. To our knowledge, this is the study with the longest time series carried out in South America. The results showed that the TSP concentrations for urban and industrial regions exceeded the suggested limit (80 mu g m-3) for nearly all years examined. PM10 concentrations remained above or very close to the limit (50 mu g m-3). In several sites, there was a decrease, along the years, in atmospheric particulate matter concentrations, which may be coupled to improvements of fossil fuels and replacement by lesspolluting fuels, such as hydrated alcohol and natural gas. However, in other places, high particulate matter concentrations were observed, which are associated with the infrastructure development in the city and for sporting events. The results show a seasonal trend during the study period, which is characterized by high levels of particulates during the austral wintertime. This trend is related to low rainfall and air mass stagnation. Regarding the daily concentrations observed, a tendency for high concentrations in the early morning and late afternoon was observed in urban regions, due mainly to traffic. In the industrial area, the variation was lower and more dependent on industrial activities than on traffic.