Preliminary study of in-car air pollution using optical particle counters

In past decades, a surge in vehicle imports has been witnessed in almost all African countries. These vehicles are old and use low quality fuels, producing significantly higher tailpipe emissions than newer car. Most roads are unpaved or poorly maintained adding further emissions due to resuspension of road dust due to wind and vehicle movement. On the other hand, traffic congestion has become an issue in most megacities, adding to already worsening air quality caused by industrial and domestic emissions. Available literature on traffic related air pollution has mostly focussed on dispersion of traffic exhausts, besides discussing contribution from tyre wear and road conditions. However, there is a lack of studies on personal exposure of drivers and passengers to air pollution. Personal exposure of individuals depends on the time spent in different microenvironments and level of pollution in each microenvironment. If we focus on travel mode, personal exposure of drivers and passengers can vary significantly by the mode: motorbikes, cars, buses, taxis, local trains etc., and the route taken by each journey, indicating temporal and spatial variations in exposure to air pollution. In this study, we present first results of an ongoing evaluation of air pollutants concentration in various transportation systems. A set of instruments including a Particles Plus 8301-AQM1 Series handled particle counter, an IQAir AirVisual Pro, and a temtop M2000 2nd are used to measure PM, CO2, and TVOC concentrations. Several means of transportation including horse carriages, motorbikes, taxis, and minibuses were examined along with their itineraries in the city of Thiès in Senegal. During this first phase, other sources of pollutants unexpected were identified including maintenance of vehicles, open burning of solid waste on roadsides, infiltration of exhaust inside vehicle cabins, dusty seats, etc. Unregulated and congested traffic could increase the exposure duration specially at roundabouts or on congested roads. In-vehicle levels of concentrations higher than the outside levels, suggesting increased exposure risk of drivers and passengers. The situation may be critical in crowded minibuses carrying sensitive and vulnerable population groups (children elderly, pregnant women, and those with existing health conditions).