Pollution Characteristics Of PM_2.5 And PM₁₀ In Four Types Of Public Indoor Places

ObjectiveTo determine particulate matter smaller than 2.5μm (PM_2.5) and particulate matter smaller than 1Oμm (PM₁₀) levels in various public indoor places, and explore the possible influencing factors.MethodsSampling was performed at 20 public places in four types, including restaurant, coffee house, internet bar and cinema during January 2013 to March 2014. Both indoor and outdoor PM_2.5 and PM₁₀ levels were measured by light scattering method using TSI8532 sampling instrument.The general information was also collected from these places at the same time, included monitoring spots volume, indoor temperature, indoor relative humidity, CO and CO₂ concentration, atmospheric pressure, indoor staff activity, smoking status, ventilation conditions and stove using.The influence factors of indoor PM_2.5 concentrations were examined using logsitic regression model.Results1. Level and its associated factors for indoor PM_2.5The median indoor PM_2.5 concentrations of all 20 public places was 133.73（IQR:74.96-259.28）μg/m³, ranging from 12.28 to 1227.60μg/m³, while in restaurant, coffee house, internet bar and cinema were 140.99μg/m³,288.67μg/m³,220.78μg/m³ and 74.77μg/m³ respectively.The indoor/outdoor （I/O） ratio of PM_2.5 was 1.72（IQR:0.97-3.83）, ranging from 0.50 to 42.50, while in restaurant, coffee house, internet bar and cinema were 1.51,5.19,3.35 and 0.94 respectively.The contribution rate of indoor PM_2.5 to PM₁₀ was 67.35 （IQR:63.99-69.53）%, ranging from 55.99 to 79.03%. The contribution rate of outdoor PM_2.5 to PM₁₀ was 61.49 （IQR: 57.38-65.43）%, ranging from 48.97 to 71.74%.Univariate analysis results showed summer（OR=0.10,95%CI:0.03-0.32）, autumn （OR=O.2O,95%CI:0.06-0.66）,17-24p.m.（OR=4.38,95%CI:1.05-18.30）, monitoring stations located in the second floor(（OR=2.50,95%Ci:1.11-5.64）, monitoring spots volume bigger than 410.00m³（OR=0.44,95%CI:0.22-0.86）, outdoor PM_2.5 concentration higher than 75μg/m³（OR=4.60,95%CI:2.01-10.51）, outdoor CO concentration higher than 0.45mg/m³（OR=1.97,95%CI:1.01-3.85）, outdoor CO₂ concentration higher than 471.00mg/m³（OR=2.10,95%CI:1.07-4.12）, indoor CO concentration higher than 1.30mg/m³（OR= OR=2.30,95%CI:1.16-4.55）, indoor CO₂ concentration higher than 863.50mg/m³（OR=2.22,95%CI:1.13-4.36）, smoking （OR=11.34,95%CI:3.37-38.20）, intermittent air blast（OR=5.74,95%CI:1.93-17.11）, split type air conditioner（OR=10.50,95%CI:1.99-55.48）, no air conditioner（OR=13.27, 95%CI:2.59-68.04）, fresh air system（OR=0.28,95%CI:0.11-0.69） were related to indoor PM_2.5 concentration.Multivariate logistic regression model indicated that outdoor PM_2.5 concentration higher than 75μg/m³（OR=6.34, 95%CI:1.25-32.21）, smoking（OR=85.16,95%CI:11.32-640.67）, intermittent air blast（OR=52.56,95%CI:3.70-747.04）, no air blast（OR= 19.92,95%CI: 2.99-132.59） and stove using（OR=7.15,95%CI:1.22-42.06） were risk factors for PM_2.5 concentration according with standard. Summer（OR=0.05,95%CI:0.01-0.43） and fresh air system（OR=0.07,95%CI:0.01-0.44） were protective factors.2. Level and its associated factors for indoor PM₁₀The median indoor PM₁₀ concentration was 205.98（IQR:109.68-375.44）μg/m³, ranging from 19.26 to 1984.85μg/m³, while in restaurant, coffee house, internet bar and cinema were 207.31μg/m³,422.38μg/m³，312.97μg/m³ and 108.61μg/m³ respectively.The indoor/outdoor （I/O） ratio of PM₁₀ was 1.55（IQR:0.90-3.52）, ranging from 0.40 to 33.26, while in restaurant, coffee house, internet bar and cinema were 1.37,3.75,3.20 and 0.87 respectively.Univariate analysis results showed summer（OR=0.22,95%CI:0.09-0.55）, autumn （OR=0.34,95%CI:0.14-0.83）, outdoor PMio concentration higher than 150μg/m³ （OR=7.41,95%CI:3.14-17.49）, outdoor CO concentration higher than 0.45mg/m³ （OR=2.Q9,95%CI:1.14-3.83）, outdoor CO₂ concentration higher than 471.00mg/m³ （OR=2.16,95%CI:1.18-3.96）, indoor CO concentration higher than 1.30mg/m³ （OR=230,95%CI:1.25-4.24）, indoor CO₂ concentration higher than 863.50mg/m³ （OR=2.30,95%CI:1.26-4.23）, smoking（OR=9.38,95%CI:3.78-23.28）, split type air conditioner（OR=17.91,95%CI:2.10-152.42）, no air conditioner（OR=15.59,95%CI: 1.88-129.16） and stove using（OR=2.83,95%CI:1.23-6.54） were related to indoor PM₁₀ concentration.Multivariate logistic regression model indicated that outdoor CO concentration higher than O.45mg/m³（OR=4.27,95%CI:1.53-11.96）, outdoor PM₁₀ concentration higher than 150μg/m³（OR=25.33,95%CI:7.37-87.10）, smoking（OR=51.20,95%CI:11.44-229.24）, intermittent air blast （OR=5.87,95%CI:1.27-27.26）, no air blast（OR=9.85,95%CI: 1.97-49.26） and stove using（OR=22.80,95%CI:5.11-101.74） were risk factors for PM₁₀ concentration according with standard. Fresh air system（OR=0.18,95%CI:0.04-0.90） and monitoring stations located in the fourth floor（OR=0.10,95%CI:0.02-0.66） were protective factor.ConclusionThe indoor PM_2.5 and PM₁₀ pollution in four types of public places is serious. The outdoor PM_2.5 and PM₁₀ concentration, ventilation conditions smoking and stove using were the most important influencing factors. The results of this study call for effective implementation and enforcement of smoke-free environment and keeping good indoor ventilation at public places in the city.