[Air pollution and respiratory disease in a tropical urban setting in Cotonou, Benin]

To assess the impact of air pollution inside and outside housing on respiratory function in people living around traffic intersections.

A descriptive analytical study was carried out from February 5 to July 5, 2006. Carbon monoxide (CO), sulfur dioxide (SO2), and nitric dioxide (NO2) were measured over an 8-hour period inside and outside 60 houses near intersections during periods of heavy and light traffic. Spirometry was performed on residents of the same houses.

CO levels were higher during heavy than light traffic both inside houses: 65 ppm vs. 43.2 ppm and outside houses: 160 ppm vs. 115 ppm. Similar results were observed for SO2, i.e., 2.8 ppm vs. 0.49 ppm inside houses and 4.3 ppm vs. 0.83 ppm outside houses. Measurements for NO2 were consistently nil. Respiratory symptoms were more frequent during heavy than light traffic: p = 0.0001; odds ratio (OR), 4.73; confidence interval (CI), 2.13-10.51. The frequency of spirometric abnormalities was higher in heavy than light traffic: p = 0.004; OR, 5.78; CI, 1.43-27.10.

Indoor pollution level is higher during heavy traffic than light traffic. Respiratory symptoms were greater during heavy than light traffic.