Background In Brazil, many cities are surrounded by sugar cane plantations, and when these plantations are burnt prior to harvesting, millions of people are exposed to the smoke from these fires from May to November every year.

Methods A daily time-series regression analysis was conducted in a city located in the sugar cane plantation region of São Paulo State, Brazil, between 1 February 2005 and 31 July 2007. The percentage increase in the number of pneumonia-related emergency department visits (PEDV) associated with a 10 µg/m³ increase in the total suspended particles (TSP) concentration was measured, including any effects that were delayed for up to 6 days.

Results A total of 1505 PEDV (a median of two events per day) were analysed. During the burning period, there was an acute effect that began on the day of exposure and remained for 2 days. An increase of 6% (95% CI 2.4 to 9.9) in PEDV was observed for the 2 days following the TSP increase. This pattern and the size of the effect were similar to those observed for the whole period and also during the non-burning period.

Conclusions Increases in TSP concentrations were found to be associated with increased PEDV in a region affected by air pollution from sugar cane burning. This finding reinforces the need for polices and efforts to ban sugar cane burning prior to harvesting.