Exposure to PM2.5 Related to Road Traffic: Comparison between Crossroads and Outside of Crossroads at Cotonou, Benin

Background: Several studies have analysed the pollution issues owing to road traffic in Cotonou, Benin. Concentration levels of particles are higher on high traffic than a low traffic. The exposure of human populations to air pollution is more intense on the roads. In Benin, the density of traffic on the crossroads is indeed more important. Are traffic locations such as crossroads, areas where the level of exposure PM2.5 is increased? Methods: This study was conducted along the 5 km high-traffic road in the city of Cotonou. It is a high traffic lane with two crossroads. Sampling and measurements were carried out in dry sea-son (January and February) and rainy season (June and July). For each season the measurements were made over two months from 7 am to 9 pm. PM2.5 measurements were made at different locations at crossroads and also along the track. To compare concentrations of PM2.5 at crossroads and outside of roundabout, we used the Generalized Linear Mixed Model. Results: In the rainy season the PM2.5 hourly concentrations ranged between 400 μg/m3 and 500 μg/m3 while in the dry season 100 μg/m3 and 300 μg/m3. In the rainy season, the average of PM2.5 concentration was 463.25 ± 66.21 μg/m3 at crossroads and 264.75 ± 50.97 μg/m3 outside of crossroads. In the dry season, the average of PM2.5 concentration was 232.75 ± 97.29 μg/m3 at crossroads and 123.31 ± 63.79 μg/m3 outside of crossroads. Both in dry and rainy seasons, PM2.5 concentration level peaks are observed from 7 am to 9 am and from 7 pm to 9 pm. The Generalized Linear Mixed Model showed that there is high significant difference between concentrations of PM2.5 at crossroads compared to outside of crossroads. Occupation of the roadside (in particular crossroads) for various economic activities is common practice in Cotonou thus health risk for people working around crossroads increases. Conclusion: Locations such as crossroads are areas where the level of exposure PM2.5 is highest on road traffics.

Respiratory Symptoms Associated with Workplaces Located along a Road with High-Traffic at Cotonou, Benin

Objective: Air pollution is becoming one of the public concerns requiring urgent feasible response per local context. Defining accurately the level of exposure of outdoor air pollution effect on health of venders working along main roads and roundabouts with high traffic is important. This study was conducted to assess respiratory health risks on venders associated with different geographical positions in Cotonou. Methods: A cross-sectional study was conducted along the main road with high traffic including three roundabouts in Cotonou. The 194 study participants from all shops, one respondent per shop, were given a unique GPS data associated to indicate the shop’s geographical position. The study employed validated questionnaire on respiratory symptoms. Results: Study participants had mean age of 36.26 (±11.65) years with sex ratio of (M/F) 1.8. Majority (72.7%) of study participates reported to have at least one respiratory symptom and 69% of them were working in non-ventilated rooms. The proportion of having at least one respiratory symptom was significantly different (p Conclusion: Working in roundabout is associated with more respiratory symptoms than working in shops along main road. Air pollution mitigation efforts should focus in such settings, taking into account the sub-population of workers in resource limited countries.