Using a Gaussian model to estimate the level of particle matter concentration on paved and unpaved roads in urban environment: A case study

Abstract

Introduction: In both developed and developing countries, re-suspension of dust particles along the road owing to tire and brake wear is the most common source of Particulate Matters (PM) pollution in metropolitan areas. This study in Douala analyses the effects of paved and unpaved roads on particle matters concentration thresholds in urban environments. Materials and methods: The United States Environmental Protection Agency (US EPA)'s model AP-42 equations were used to calculate the amount of particle matter emissions on the roads. Between 6 am and 8 pm, a traffic analysis using information from the city of Douala was conducted. The busiest times for traffic were from 8 to 9 a.m. and 6 to 7 p.m. We applied a two-dimensional Gaussian model to determine the particle concentration. Two different scenarios were taken into account: Compared to Scenario 2 (S2), Scenario 1 (S1) represents an unpaved road. The PM10 and PM2.5 types of particles were the main topics of interest. Results: We obtained for S1, around 917.70 µg/m3 and 559.00 µg/m3 respectively for PM10 and PM2.5. We got roughly 170.00 µg/m3 and 103.90 µg/m3 for S2, respectively for the two particles. The amount of silt deposited on the road, the kind of road (paved or unpaved), the number, and the types of vehicles moving all influence the emission of road dust re-suspension. Regardless of particle size, these pollution levels are beyond World Health Organization (WHO) recommended norms. Conclusion: This study offers important information on Douala's pollution levels, which can be a significant cause of disease in the area and should be considered.

Keywords

• AP-42 model; Road traffic; Douala air pollution; Silt loading; Paved and Unpaved road