Abstract：Objective To perform an assessment of microbiological contamination on daily self-inhaling respirator for particulate during haze days so as to provide the recommended cumulative wearing time and improve the protective level of public health. Methods The used particulate respirators during haze days were collected, and their basic information was recorded. The total bacterial count, total fungal count and hemolytic bacteria count of inner and outer materials of the respirators were detected separately. The strains were identified by 16S rRNA gene sequence analysis, and the fitting curves of microbiological indicators and cumulative wearing time were drawn. Results The amount of microorganism attached to inner materials of daily self-inhaling respirators was positively correlated with the cumulative wearing time, and the fitting curve of the total bacterial count and total fungal count was drawn (R2 total bacterial count=0.994, R2 total fungal count=0.965). There was no obvious correlation between the amount of microorganism attached to outer materials and the cumulative wearing time. The total bacterial count and the total fungal count in inner materials of the respirators both increased rapidly when the cumulative wearing time was up to 5-7 hours. The isolated bacterial strains from inner and outer materials of the respirators were mainly Firmicutes, Actinobacteria and Proteobacteria, especially Bacillales. Most of the isolated strains were non-pathogenic bacteria, and only one strain of Staphylococcus aureus was isolated from the inner materials. Conclusions The amount of microorganism attached to inner materials increases with the increment of cumulative wearing time and frequency; moreover, it rapidly increases and the detection rate of pathogenic or conditional pathogenic bacteria also increases when the cumulative wearing time is up to 5-7 hours. So the cumulative wearing time of a respirator should be controlled under 7 hours by healthy people and under 5 hours by susceptible people.
2018, Vol. 25 
