Abstract:
Objective To investigate the distribution of fine particulate matter (PM2.5) at urban transit system waiting rooms across China and their influencing factors, and to provide data support for establishing PM2.5 limits and pollution prevention and control strategies in public places such as waiting rooms.
Methods PM2.5 concentrations were measured with the light scattering method in the indoor and outdoor spaces of 126 waiting rooms sampled across 32 provinces in the warm season (May to October) and the cold season (November to next April) in 2019. Sampling points were set based on the area of waiting rooms.
Results In 2019, the median (P25, P75) mass concentrations of indoor and outdoor PM2.5 at waiting rooms were 35.5 (17.5, 57.0) μg/m3 and 41.0 (24.0, 69.0) μg/m3, respectively. The median (P25, P75) indoor-to-outdoor ratio (I/O) for PM2.5 was 0.89 (0.61, 1.09). The Kruskal-Wallis test detected significant regional differences in indoor PM2.5 (χ2=61.26, P < 0.001), outdoor PM2.5 (χ2=27.83, P < 0.001), and I/O (χ2=35.07, P < 0.001), all being the highest in Central China. Indoor PM2.5 concentrations and the I/O ratio could be associated with the height, area, operating hours, and passenger flow of waiting rooms.
Conclusion There are significant regional disparities in indoor and outdoor PM2.5 distributions at waiting rooms across China. Therefore, it is imperative to establish dynamic monitoring systems, formulate region-specific governance strategies, and implement targeted measures to improve indoor air quality in public places.
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