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BackgroundThe subway environment, characterized by dense crowds, relatively enclosed architectural structures, and insufficient ventilation, poses various health hazards. Population health risk attributable to subway hygiene have become an important public health issue. ObjectiveTo evaluate the current environmental hygiene of metro line X in Nanjing, and to provide a scientific basis for the prevention and control of harmful factors and the establishment of relevant standards. MethodsStation halls, platforms, and carriages of Nanjing metro line X were monitored in March 2023. Six stations were selected by stratified sampling, and monitored once during the morning peak hours (9:00—11:00). Carriage monitoring was conducted after a full day of operation (21:00—22:00). The monitoring indicators included physical factors such as temperature, relative humidity, wind speed, illuminance, and noise (A-weighted); air quality factors such as carbon dioxide (CO2), carbon monoxide (CO), respirable particulate matter (PM10), fine particulate matter (PM2.5), ammonia (NH3), formaldehyde, benzene, toluene, xylene, total volatile organic compounds (TVOC), ozone (O3), total bacterial count, and total fungi count; hygiene status of the inner surface of the central air conditioning ventilation system, such as dust accumulation, total bacterial count, and total fungi count; supply air, such as PM10, PM2.5, total bacterial count, and total fungi count; and surface microorganisms on objects, such as total bacterial count, total fungi count, coliform bacteria, and Staphylococcus aureus. Results were evaluated and discussed according to Hygienic indicators and limits for public places (GB 37488-2019) and Hygienic specification of central air conditioning ventilation systems in public buildings (WS 394-2012). ResultsThe environmental temperature medians (P25, P25) in the platforms and carriages of Nanjing metro line X were 20.7 (19.95, 21.65) ℃ and 21.8 (19.80, 35.80) °C, respectively, which exceeded the standard limits. The relative humidity and noise level in the carriages were 38.80% (24.6%, 46.3%) and 79.50 (76.25, 82.00) dB, respectively, failing to meet the national health standards. The total fungi count in supply air in 22.2% of the monitoring points exceeded the standard value. Coliform bacteria and Staphylococcus aureus were detected on the surfaces of some high-touch objects, with the bathroom faucet being the most severely contaminated. The medians (P25, P25) of temperature [21.8 (19.8, 35.8) ℃], wind speed [0.48 (0.39, 1.02) m·s−1], noise [79.5 (76.25, 82.00) dB, and CO2 content [0.079% (0.070%, 0.091%)] in the carriages were higher than those in the station halls and platforms (P |
