Investigating the influence of platform design on the distribution of traffic particulate matter at the bus stop.

Passengers waiting at bus stops are regularly exposed to vehicle emissions from nearby roads. Thus, comprehending the pollution levels within the stop is crucial for devising measures to improve the waiting environment. Here, we measured PM 2.5 and black carbon (BC) concentrations at bus stops and simulated the effects of different bus platforms on particle distribution under varying winds. The main findings are: (1) Particle concentrations were higher in the front of the bus stop than in the rear. The exit area of the bus stop at downwind of the road showed the highest concentration, especially for BC, with a maximum increase of 58% compared to other front locations, likely attributed to increased emissions from road vehicles interfered by departing buses. PM 2.5 concentrations at the stop increased by 21–38% in the evening compared to the morning, while BC concentrations decreased by about 27% due to a reduction in diesel vehicles and increased wind speeds. (2) As wind-road angle increased, turbulence caused particles from the road to migrate towards the stop and its rear. A 45° wind-road angle facilitated particle diffusion, while higher wind speeds brought an overall reduction in particulate matter. These results varied among the three simulated bus platforms, with differences more pronounced for PM 2.5 than for BC. (3) Enhancements in the front enclosures of the bus stop promoted a significant decrease in particles behind the stop, particularly in BC compared to PM 2.5. Therefore, installing closed or semi-enclosed front barriers, considering prevailing wind conditions, has the potential to improve air quality within the bus stop. • Front area of the bus stop has obviously higher pollution than the rear area. • PM 2.5 and BC show distinct variations at the bus stop with time and location. • Winds affect PM 2.5 more than BC in terms of turbulence intensity. • Front enclosures of the bus stop better reduce passenger exposure to pollution. [ABSTRACT FROM AUTHOR]