Influence of vehicular traffic density on hospital admissions due to respiratory tract cancer in the city of São Paulo, Brazil

Pollution related to traffic is a major problem in urban centers and a large portion of the population is vulnerable to its health effects. This study sought to identify a potential association between hospital admissions due to respiratory tract cancer and vehicular traffic density in the city of São Paulo, Brazil. It is an ecological study of the public (Hospital Inpatient Authorization - AIH, in Portuguese) and private (Hospital Inpatient Communication - CIH, in Portuguese) health care systems, from 2004 to 2006, geocoded by individuals’ residential addresses. Using a Besag-York-Mollié ecological model, we initially evaluated the relationship between number of cases of hospital admission due to respiratory tract cancer in each weighting area and the standardized co-variables: traffic density and Municipal Human Development Index (MHDI) as indicator of socioeconomic status. Using a classic Poisson model, we then evaluated the risk associated with growing traffic density categories. The Besag-York-Mollié model estimated a RR = 1.09 (95%CI: 1.02-1.15) and RR = 1.19 (95%CI: 1.10-1.29) of admission due to respiratory tract cancer for each increase of one standard deviation of traffic and MHDI, respectively. The Poisson model also showed a clear exposure-response gradient for admission due to respiratory tract cancer (IRR = 1.11; 95%CI: 1.07-1.15, for each 10 units of added traffic density). This study suggests that there is an association between residing in areas with high traffic density and hospital admissions due to respiratory tract cancer in the city of São Paulo.

Keywords:
Vehicle Emissions; Air Pollution; Respiratory Tract Neoplasms; Hospitalization; Spatial Analysis