title: [Effect of humidity and temperature on filter and gravimetric measurement of ambient particulate matter in a balance room].
abstract: OBJECTIVE
  To assess the effects of the alteration of humidity and (or) temperature on weight of filters without and with ambient particulate matter in a balance room.
  
  
  METHODS
  The mass of blank dust sampling filters were weighed under (18 +/- 1) degrees C and (28 +/- 1) degrees C respectively, with the humidity varying from 35% relative humidity (RH) to 100% RH in a balance room. Then the blank filters were divided into two groups and were used to sample total dust and respirable dust. After sampling, the loaded filters were re-weighed under above conditions and the mass difference before and after the sampling were compared and analyzed.
  
  
  RESULTS
  The vibration of the average mass of filters varied from 0.10 to 0.13 mg and from 0.06 to 0.09 mg under the temperatures of (18 +/- 1) degrees C and (28 +/- 1) degrees C respectively; When both the temperature and humidity changed, it varied from 0.12 to 0.16 mg. The deviation of average mass difference ranged from 0.07 to 0.10 mg and from 0.04 to 0.08 mg under the two temperatures mentioned above; When both the temperature and humidity changed, it varied from 0.09 to 0.14 mg. The average mass of blank filters and loaded filters were all positively correlated with the change of humidity (P < 0.01). No effects of humidity on the average mass difference of the loaded filters were observed. The average mass differences of loaded filters and blank filters under (18 +/- 1) degrees C were significantly higher than that under (28 +/- 1) degrees C (P < 0.01) when humidity was not changed.
  
  
  CONCLUSIONS
  The alteration of humidity and (or) temperature in a balance room attributes to the deviation of the measurement of the mass of filters and thus affects the gravimetric measurements of ambient particulate matter.
authors: MOE Key Lab of Environmental and Health and Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China.
authors: Wen-jin
authors: WJ
authors: Su
authors: Li-min
authors: LM
authors: Wang
authors: Shao-fan
authors: SF
authors: Weng
authors: Hai-jiao
authors: HJ
authors: Wang
authors: Li-li
authors: LL
authors: Du
authors: Yue-wei
authors: YW
authors: Liu
authors: Lei
authors: L
authors: Yang
authors: Wei-hong
authors: WH
authors: Chen
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation; D005374:Filtration / Q000295:instrumentation; D006813:Humidity; D052638:Particulate Matter / Q000032:analysis*; D013696:Temperature
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter