| With the development of industrial and intensive livestock and poultry breeding industry, how to dispose of the pollution from the large-scaled poultry and livestock breeding farms has become one of the most urgent problems to be sloved in livestock and poultry breeding industry. Odorous pollutants exhausted from livestock and poultry farms have caused the strong dissatisfaction with the surrounding residents. These odorous pollutants not only serious harm human health, but also seriously affect the surrounding air quality. In this context, the horizontal dispersion law of odorous pollutants was studied along different distance between monitoring points and the odor source from 0 meters to 300 meters. The meteorological factors (i.e. wind speed, temperature and atmospheric stability) were also considered. The method of determining the odor protective distance was also discussed.This paper firstly summarized and analyzed the existing research results of research objects at home and aboard and the basic situation of atmospheric meteorological features in experimental area. Then, in the monitoring work, NH3, H2S and odor concentration were selected as monitored indexes of the emissions and diffusion concentration of odorous pollutants. Three moderate scale farms (cows, pigs and layers) in Shandong province were selected as experimental sites in summer of 2009.Then the monitoring results were analyzed. Based on this, the horizontal dispersion law of odorous pollutants was studied along different distance between monitoring points and the odor source from 0 meters to 300 meters, and the meteorological factors of odor pollutants diffusion was also analyzed. Furthermore, this paper summarized the existing relevant standards of farm health protection distance of China in current, and used three methods including health protection distance formula, SCREEN3 model for estimating atmospheric environment protective distance and a guide line approach to calculate the reasonable separation distance for odor from research objects to avoid odor nuisance.Through analysis and compare results, the main conclusions were as follows:(1)For poultry and livestock breeding farms (cows, pigs and layers), farms emi ssions concentration of NH3 was higher than H2S of odorous pollutants. So in the livestock and poultry farm, NH3 was the main component of odorous pollutants. And the relative value scope of odours concentrations from livestock farms was higher than dairy farms and layer farms.(2)The emission concentration odours pollutants form livestock and poultry farms can be influenced obviously by animal species, breeding forms, feces management forms.Results also showed outdoor temperature had significant effect on odour concentrations, and the effects of air relative humidity were not significant.(3)Odor concentration decreases exponentially as a function of distance between monitoring points and the odor source. For meteorological factors, with outdoor temperature of about 32℃and air relative humidity of about 30%, wind speed had significant influence on odor concentrations (P<0.05). When wind speed was below 2m/s, and air relative humidity was about 30%, outdoor temperature(27～37℃) affected odor concentrations significantly at P<0.05, and odor diffusion ability was strongest at 32℃; when outdoor temperature was about 32℃, wind speed was below 2m/s, odor concentration decreased significantly with the increase of air relative humidity. Arranging the meteorological factors of odor pollutants diffusion, temperature and wind speed were more important than air relative humidity.(4)Research results showed that, the separation distance of a stench having 600 cows was 300m; of a livestock of 530 pigs was 381m; and the separation distance of a layer farm of 4000 layers was 340m.(5)It was reasonable that using health protection distance formula to calculate a separation distance between the odour source and residential areas.
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