Status and influencing factors of air microbial pollution in hotel rooms in China, 2022

Objective  To investigate the current status of air microbial pollution (total bacterial and fungal counts) in hotel rooms in China and analyze the main influencing factors.

Methods  A total of 5 484 rooms from 2 302 hotels were selected by stratified random sampling in 2022. The total bacterial and fungal counts in the indoor air were determined, and the relevant physical indicator measurements and information surveys were carried out simultaneously. The multipie logistic regression analysis was used to analyze the main influencing factors for the exceedance of indoor air microorganisms.

Results  The medians of total bacterial and fungal counts in the indoor air were 247 CFU/m³ and 160 CFU/m³, respectively, and their exceedance values were 1 500 CFU/m³ and 500 CFU/m³, with the excess rates of 4.21% and 20.95%, respectively. Compared with hotels with three stars and above, hotels with less than three stars had a higher risk of exceedance of the total bacterial count in the air of rooms (odds ratio(OR)=1.30, 95% confidence interval (CI): 1.02-1.67); compared with hotels in the eastern region, hotels in the central and western regions had a higher risk of exceedance of the total bacterial count in the air of rooms (central region: OR=1.43, 95%CI: 1.01-2.04; western region: OR=1.48, 95%CI: 1.04-2.12). The risk of exceedance of the total fungal count in rooms was higher in hotels with>10 years of operation compared to those with ≤5 years of operation (OR=1.24, 95%CI: 1.04-1.48); the risk of exceedance of the total fungal count in rooms of hotels renovated over the past two years was lower than that in hotels that had not been renovated over the past two years (OR=0.76, 95%CI: 0.62-0.93). The risk of exceedance of air microorganisms in rooms was positively correlated with the indoor temperature and inhalable particulate matter (PM₁₀) level and negatively correlated with the carbon dioxide (CO₂) level (P < 0.05). The risk of exceedance of total fungal count was negatively correlated with the air velocity in rooms (OR=0.37, 95%CI: 0.21-0.63) and positively correlated with the relative humidity (OR=1.02, 95%CI: 1.01-1.02). No significant correlation was found between the risk of exceedance of total bacterial count in the air and the air velocity or relative humidity.

Conclusion  The situation of air microbial pollution in hotel rooms in China is not optimistic. The size of the premises, regional distribution, indoor temperature, CO₂, and PM₁₀ of hotels are influencing factors for the exceedance of total bacterial count in rooms; the years of opening, renovation in the past two years, indoor temperature, relative humidity, air velocity, CO₂, and PM₁₀ of hotels are influencing factors for the exceedance of total fungal count in rooms.