Objective To investigate the pollution status, vertical distribution and concentration variation within 24 hours of total suspended particles ( TSPs) , paniculate matter ≤ 10 μm ( PM10) , particulate matter ≤ 5(PM5 )and particulate matter ≤2.5 μm(PM2.5) in major functional areas of Suzhou and the protective effect of different type masks on particulate matter. Methods (1) The concentration of atmospheric TSPs, PM10, PM5 and PM2. 5 in seven functional areas in Suzhou was monitored for three consecutive days. (2) A residential building of 25 stories was chosen and the concentration of TSPs, PM10, PM5, PM2. 5 was detected at the 1st, 5th, 10th, 15th,20th and the 25th floor respectively. ( 3 ) The concentrations of the four particulate matter were detected every two-hours for three consecutive days to investigate how concentration of particulate matter varies within 24 hours. (4) The concentration of the four kinds of particulate matter was analyzed with the sampling head of monitor wrapped with disposable non-woven medical mask, fashion-type mask, gauze mask or activated carbon anti-dust mask respectively, and the protective effect of the four masks on particulate matter was compared. Results (1) The concentration of PM2. 5 was higher than the national health limit in all seven functional areas in Suzhou. (2) No significant difference in vertical distribution of particulate matter was found among different floors in residential buildings (P > 0. 05). (3) Two small peaks of particulate matter appeared in the morning and evening respectively while the top appeared at dawn ( P < 0.05). (4) Disposable non-woven medical mask showed the best protective effect on particulate matter among the four tested masks. Conclusion PM2.5 is the main particulate matter in Suzhou area. In addition the 4 kinds of particulate matter: TSP, PM10, PM5 and PM2. 5 are of higher concentration in the early morning. No significant difference was detected from an altitude of less than 75 meters. Disposable non-woven medical masks is suggested to be used for defending people from particulate matter in daily life.%目的 探讨苏州市主要功能区总悬浮颗粒物(TSP)、可吸入颗粒物(粒径≤10 μm,PM10)、粒径小于5μm的颗粒物(PM5)、细颗粒物(粒径≤2.5μm,PM2.5)等4种大气颗粒物的污染状况、垂直分布特征、24h浓度变化,以及不同类型口罩对大气颗粒物的防护效果.方法 (1)在苏州市选取7个功能区,连续3d监测大气中TSP、PM10、PM5、PM2.5的浓度；(2)选取一栋25层高的居民楼,分别检测第1、5、10、15、20、25层楼大气中TSP、PM10、PM5、PM2.5的浓度；(3)选取一监测点,每2h监测1次大气颗粒物浓度,连续测定3d,观察24h内颗粒物浓度变化；(4)分别使用一次性无纺布医用口罩、时尚型口罩、棉纱口罩、活性炭防尘口罩裹住采样头后监测4种大气颗粒物的浓度,比较不同类型口罩的防护效果.结果 (1)7个功能区PM2.5浓度均超标；(2)不同楼层间大气颗粒物浓度差异无统计学意义(P＞0.05)；(3)大气颗粒物浓度在早晨和傍晚各出现1个小高峰,凌晨时大气颗粒物污染最严重(P＜0.05)；(4)4种口罩比较,一次性医用口罩防护效果最好.结论 PM2.5是苏州地区主要大气颗粒污染物,4种大气颗粒污染物在凌晨浓度较高,在距地面75 m高的低空范围内差异无统计学意义,建议日常生活中使用一次性无纺布医用口罩来防护大气颗粒物污染.
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