Abstract:

Objective To assess the pollution level of benzene series in indoor air of public places in Sichuan Province and the potential health risks to employees，so as to provide fundamental data support for the quality management of public sanitation. Methods From 2021 to 2024，four types of public places，namely gyms，hotels，barber shops and beauty salons，were randomly selected in Chengdu City，Deyang City，Mianyang City and Ya'an City of Sichuan Province to monitor the levels of benzene，toluene and xylene in the indoor air of these public places. The exposure levels of three pollutants were analyzed，and the health risk assessment for their practitioners was conducted in accordance with the health risk assessment model recommended in the Technical Guidelines for Environmental Health Risk Assessment of Chemical Substances（WS/T 777-2021）. Results From 2021 to 2024，a total of 2 545 benzene series samples were detected，the detection rates of benzene，toluene and xylene were 45.30%，47.78% and 49.00%，respectively，and the qualified rates were 98.98%，99.69% and 99.61%，respectively. The differences in the concentrations of benzene，toluene，and xylene were statistically significant（H=69.343，35.645，133.299，all P<0.01），and the pollution level of benzene was the highest in 2021. The median（M） detection concentrations of benzene，toluene，and xylene were 0.085，2.290 and 8.600 μg/m³，respectively，and their chronic non-carcinogenic hazard quotient（HQ） were 8.75×10^-4，1.41×10^-4，2.66×10^-2，respectively. The carcinogenic risk（CR） of benzene was 8.77×10^-8. There were significant differences in the concentrations of toluene and xylene among different places（H=19.729，16.869，both P<0.01）.The pollution levels of toluene in gyms and beauty shops were higher，with the median detection concentration of 2.000 μg/m³，and the HQ was 1.24×10^-4. The highest contamination level of xylene was found in beauty shops，with a median concentration of 4.000 μg/m³，and HQ was 1.23×10^-2. There were significant differences in the concentrations of toluene and xylene among different seasons（Z=-5.521，-9.090，both P<0.01）. The concentration of xylene in winter was higher than that in other seasons，with a median concentration of 0.100 μg/m³，and its HQ was 3.09×10^-4.The cumulative probability distribution of health risks showed that the cumulative percentages of benzene，toluene and xylene HQ less than 1 were 98.86%，100.00% and 99.88%，respectively. The cumulative percentage of benzene CR below 10^-6 was 59.02%，the cumulative percentage between 10^-6 and 10^-4 was 39.84%，and there was a maximum value of 1.14% greater than 10^-4. Conclusion The overall qualified rate of benzene series in indoor air of public places in Sichuan Province is high，and the non-carcinogenic and carcinogenic risks of benzene series in indoor air of some places are high，which has a certain health risk to employees，and attention should be paid to it.

Key words: Public places, Indoor air, Benzene, Toluene, Xylene, Health risk assessment