title: A passive noise control approach utilizing air gaps with fibrous materials in the textile industry.
abstract: BACKGROUND
  Noise pollution is currently a major risk factor in industries in both developed and developing countries.The present study assessed noise pollution in the knitting industry in Iran in 2009 and presented a control method to reduce the rate of noise generation.
  
  
  METHODS
  The overall noise level was estimated using the network environmental noise assessment method in Sina Poud textile mill in Hamadan. Then, frequency analysis was performed at indicator target stations in the linear network. Finally, a suitable absorbent was recommended for the ceilings, walls, and aerial panels at three phases according to the results found for the sound source and destination environment.
  
  
  RESULTS
  The results showed that the highest sound pressure level was 98.5 dB and the lowest was 95.1 dB. The dominant frequency for the industry was 500 Hz. The highest and lowest sound suppression was achieved by intervention at 4000 Hz equivalent to 14.6 dB and 250 Hz in the textile industry.
  
  
  CONCLUSIONS
  When noise control at the source is not available or insufficient because of the wide distribution of the acoustic field in the workplace, the best option is to increase the absorptive surface of the workplace using adsorbents such as polystyrene.
authors.affiliation: Department of Occupational Hygiene, School of Public Health and Center for Air Pollution Research (CAPR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Monazzam-Esmaeelpour
authors.affiliation: Department of Occupational Hygiene, School of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. z_hashemi26@yahoo.com.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hashemi
authors.affiliation: Department of Occupational Hygiene, School of Public Health and Center for Health Researches, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Rostam
authors.initials: R
authors.lastname: Golmohammadi
authors.affiliation: Department of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Narges
authors.initials: N
authors.lastname: Zaredar
mesh_terms: D000162:Acoustics; D006801:Humans; D007492:Iran; D009623:Noise, Occupational / Q000517:prevention & control*; D016273:Occupational Exposure / Q000517:prevention & control*; D013783:Textile Industry / Q000592:standards*; D017132:Workplace
keywords: Absorbent; Noise control; Technical control methods; Textile industry