Disinfection and hygiene status of reusable 3D glasses in cinemas in a district of Shanghai, China

Objective To investigate the disinfection and hygienic status of reusable 3D glasses in cinemas in a district of Shanghai, China.

Methods In January 2023, a questionnaire survey was conducted on the disinfection of reusable 3D glasses in 20 cinemas in a district of Shanghai, and 100 pairs of reusable 3D glasses were selected to test appearance, total bacterial count, and coliform bacteria. Evaluation of hygienic indicators was performed using the Hygienic Indicators and Limits for Public Places (GB 37488-2019). Chi-square test and nonparametric test were used to compare the hygiene status of reusable 3D glasses with different disinfection methods and different types of glasses.

Results In 2023, 7 disinfection methods were used for reusable 3D glasses in 20 cinemas in a certain district of Shanghai. The disinfection methods for ordinary cinemas and special cinemas were mainly 75% ethanol+ultraviolet, accounting for 73.7% and 33.4%, respectively. Among the 100 pairs of reusable 3D glasses surveyed, the overall qualified rate was 95.0% (95/100), with no coliform bacteria detected. The total number of bacteria on 5 pairs of reusable 3D glasses was>300 CFU/25 cm². The total bacterial count of reusable 3D glasses used in special cinemas M (IQR): 40 (50) CFU/25 cm² was significantly higher than that in regular cinemas M (IQR): 30 (20) CFU/25 cm² (z=-2.350, P=0.019). Among the 29 pairs of reusable 3D glasses sampled in special cinemas, 48.3% were disinfected using eyeglass cleaning machines, while the 71 pairs of reusable 3D glasses sampled in regular cinemas were not disinfected using eyeglass cleaning machines. There were no significant differences in the qualified rate of hygiene status and total number of bacteria for reusable 3D glasses disinfected by different methods.

Conclusion The hygiene status of reusable 3D glasses in cinemas in a district of Shanghai is good, but there are many disinfection methods used for 3D glasses, and it is necessary to strengthen guidance and standardization on the disinfection of reusable 3D glasses.