Investigation Of Indoor PM2.5 And PM10 In Public Places And Influencing Factors In Maanshan

Objective To investigate PM2.5 and PM10 levels both outdoors and indoors in the public places of Maanshan city, and its characteristics of seasonal change and daily variation; to discuss the influence of outdoor PM2.5 and PM10 levels, smoking and smoking policy on the indoor PM2.5 and PM10 concentration; to explore other possible influencing factors, such as human movements, central air-conditioning, mechanical ventilation and carpet; so as to evaluate the levels of people exposure to indoor PM2.5 and PM10 and health risks.Methods From January 2013 to March 2014, a total of 25 public places in five types including hotels, bath centers, internet bars, cafes and movie theatres in Maanshan city were selected as the study subjects. Both indoor and outdoor PM2.5 and PM10 concentrations were monitored by light scattering method. The general information such as the number of indoor personnels and smokers, somking policy, central air conditioner using, mechanical ventilation, as well as carpet using were also investigated. Multivariate linear regression model was used to explore the influencing factors of indoor PM2.5 and PM10 levels.Results The average indoor PM2.5 concentrations of all 25 public places were 106 (64-194) ?g/m3, ranging from 12 to 1228 ?g/m3, while the corresponding average outdoor PM2.5 concentrations were 66 (39-102) ?g/m3, ranging from 10 to 307 ?g/m3. The indoor/outdoor (I/O) ratio was 1.41 (0.98-2.85). Among the five types of public places, the average indoor PM2.5 concentration of internet bars was the highest, In addition, the average indoor PM2.5 concentrations of internet bars and cafes were significantly higher than hotels, bath centers and movie theatres (P<0.05). No significant differences of indoor PM2.5 concentration were observed in different function areas of the same type of public place (P>0.05). Indoor PM2.5 concentration of public places was statistically significant among different seasons (F= 12.248, P<0.001), showed the characteristic of lower in summer and higher in spring and winter. Also indoor PM2.5 levels of different time periods were found statistically significant (F=6.758, P<0.001), showed the characteristic of lower in the morning and higher at noon. Univariate analysis results and multiple linear regression model analysis results indicated that indoor PM2.5 concentrations were significantly correlated with corresponding outdoor PM2.5 concentrations, indoor densities of smoker and personnel, carpet using, central air conditioner using, somking policy and mechanical ventilation (P<0.05).The average indoor PM10 concentrations of all 25 public places were 159 (98-293) Hg/m3, ranging from 19 to 1985?g/m3, while the corresponding average outdoor PM10 concentrations were 105 (66-168) ?g/m3, ranging from 17 to 518 ?g/m3. The indoor/outdoor (I/O) ratio was 1.35 (0.93-2.51). Among the five types of public places, the average indoor PM10 concentration of internet bars was the highest. In addition, the average indoor PM10 concentrations of internet bars and cafes were significantly higher than hotels, bath centers and movie theatres (P<0.05). No significant differences of indoor PM10 concentration were observed in different function areas of the same type of public place (P>0.05). Indoor PM10 concentrations of public places were statistically significant among different seasons (F=13.983, P<0.001), showed the characteristic of lower in summer and higher in spring and winter. Also indoor PM10 levels of different time periods were found statistically significant (F=6.589, P<0.001), showed the characteristic of lower in the morning and higher at noon. Univariate analysis results and multiple linear regression model analysis results indicated that indoor PM10 concentrations were significantly correlated with corresponding outdoor PM10 concentrations, indoor densities of smoker and personnel, carpet using, central air conditioner using and somking policy (P<0.05).Conclution The indoor PM2.5 and PM10 pollution is serious in the five categories of public places in Maanshan. The outdoor PM2.5 and PM10 and indoor densities of smoker are the most important influencing factors. In addition, no carpet, the lower density of personnel, central air conditioner using and policy of no smoking help to reduce the indoor PM2.5 and PM10 concentrations.