Indoor air quality and air supply quality of central air conditioning ventilation systems in movie theaters in Kunshan City, Jiangsu

Background Movie theater audience are confined to luxury halls where central air conditioning ventilation systems (CACVS) are on and doors and windows are closed. The indoor air pollution in movie theaters may pose potential health risks.

Objective This study investigates the quality of indoor air and air supply of CACVS in movie theaters in Kunshan City of Jiansu.

Methods The indoor airtotal bacteria, carbon dioxide, carbon oxide, particulate matters with an aerodynamic diameter less than 10 μm (PM₁₀), formaldehyde, benzene, toluene, xylene, ozone, and total volatile organic compounds, cinema glasses (total bacteria, Escherichia coli, and Staphylococcus aureus), air supply of CACVS (total bacteria, total fungi, beta hemolytic streptococcus, and PM₁₀), air duct surface (total bacteria, total fungi, and dust accumulation), and air-conditioning cooling water (Legionella pneumophila) were monitored in 26 movie theaters of Kunshan City during September to October in 2019. The indicators of indoor air and cinema glasses were evaluated according to the Hygienic indicators and limits for public places (GB 37488-2019), and the indicators of CACVS were evaluated by the Hygienic specification of central air conditioning ventilation system in public buildings (WS 394-2012), respectively.

Results In the selected 26 movie theaters, the overall qualification rate was 92.3% (24/26). The unqualified indicators were benzene (93.6%) in indoor air, PM₁₀ (97.1%) and total bacteria (84.1%) in air supply of CACVS, and total bacteria in air duct surface (98.6%). The other indicators of indoor air, cinema glasses, air supply of CACVS, air duct surface, and air-conditioning cooling water were all qualified (100.0%). The PM₁₀ in indoor air and air supply of CACVS were correlated (R²=0.5373).

Conclusion The quality of indoor air and CACVS air supply in movie theaters in Kunshan is generally good, except benzene in indoor air, PM₁₀ and total bacteria in air supply of CACVS, and total bacteria in air duct surface which exceed the national standard limits to different degrees. Therefore, strengthening technical guidance, supervision, and management of CACVS is suggested to further improve the qualification rate of relevant hygienic indicators in movie theaters.