Objective To monitor the air quality of a slaughtering and meat processing plant and its downwind area, analyze the influencing factors and calculate the appropriate results for the setting of hygienic buffer zone.
Methods The concentrations of some air pollutants were monitored with current national standards, i.e. Air and exhaust gas-Determination of ammonia-Nessler's reagent spectrophotometry, HJ533-2009, for NH3; Standard method for hygienic examination of hydrogen sulfde in air of residential areas-Methylene blue spectrophotometric method, GB 11742-89, for H2S; Air qualityDetermination of odor-Triangle odor bag method, GB/T 14675-93, for malodor. PM10 were detected with TSI AM510 Personal Aerosol Monitor.
Results The factors influencing the concentrations of NH3, PM10, H2S and malodor substantially were sampling season (P < 0.05), sampling time (P < 0.05), the interaction between them (P < 0.05), as well as the distance downwind from the source (P < 0.05) (except PM10, P=0.068). For malodor, the influencing factors also included the interaction between sampling season and distance (P=0.032) and the interaction between sampling time and distance (P=0.025). The questionnaires of 108 randomly selected residents (100 questionnaires retrieved) who lived around the plant revealed that they were not affected by its air pollutants if they lived 300-400 m away. According to the relevant formula in Technical methods for making local emission standards of air pollutants (GB/T 13201-1991), the hygienic buffer zone was determined as 400 meters away from the meat processing plant.
Conclusion The concentrations of NH3, H2S, PM10, and malodor are influenced significantly by sampling season, sampling time, the distance downwind from the source as well as the interaction between the first two factors. The questionnaire and the formula both reveal that it is appropriate if the hygienic buffer zone is determined as 400 meters away from the meat processing plant with the slaughter capacity of 6 500 per day at the wind speed of 2-4 m/s in recent 5 years.
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