| There are only more than 50 kinds of air pollutants with enterprise boundary control limits in China’s national air pollutant emission standards.From the point of view of the types and quantities of pollutants and the scientificity of the limits,there is still a big gap from the needs of protecting public health and ecological environment around enterprises.On the basis of occupational exposure limits,a harmful factor in workplaces,321 kinds of air pollutants controlled by enterprise boundaries were screened out and classified,except the pollutants specified in the ambient air quality standards and mixed pollutants.This paper analyzed and studied the method of setting the control limits of air pollutants at the enterprise boundary and the method of estimating the Ambient Multimedia Environmental Goals(AMEG)in the current air pollutant emission standards in China,and puts forward the method of grading the limits corresponding to different types of pollutants.According to occupational exposure limits and olfactory thresholds,the control limits of air pollutants at enterprise boundary was estimated,and the differences of occupational exposure limits and olfactory threshold from different sources were compared and analyzed.The main conclusions are as follows:(1)The carcinogenic characteristics of pollutants are classified according to the list of carcinogens of the International Agency for Research on Cancer,and the toxicity is classified by the Globally harmonized system of classification and labelling of chemicals.At the same time,environmental impacts such as photochemical ozone creation,stratospheric ozone depletion and climate change of pollutants are considered.the pollutants are divided into three categories: high impact,medium impact and low impact,and the technical methods and processes for the classification of pollutant impact categories are put forward respectively.(2)Analyzed and studied the current methods for setting the limits of air pollutants at enterprise boundaries in China and AMEG estimation method,and put forward a three-level method for setting the limits corresponding to the three impact categories of pollutants.In order to make the limits more scientific,reasonable,lenient and moderate,take AMEG estimation method,the method that the maximum allowable concentration should not exceed 1/50 of that of occupational exposure limits in principle when setting the limits of air pollutants at enterprise boundaries in China,and the average values of the above two methods correspond to the limit estimates of high-impact,low-impact and medium-impact pollutants respectively.(3)The limits of air pollutants at enterprise boundaries in the current national air pollutant emission standards,Tianjin and Shanghai local odor pollutant emission standards and their formulation methods were studied,and it was found that the limits in the existing standards with a long formulation and publication period are relatively loose,so it is suggested to revise them as soon as possible.Comparing the existing enterprise boundary standard limits of 34 pollutants controlled in these standards with the limits obtained by the high,medium and low impact classification estimation method,it was found that 75.0% of the pollutants in the high impact category have a difference of more than 8 times between the two limits.so it is important to classify the pollutants with high,medium and low impact,and the pollutants with great impact on the ecological environment such as high impact category should be strictly controlled.According to the method proposed in this study,pollutants can be classified into impact categories and limits with different degrees of severity can be set to avoid the phenomenon of "one size fits all" in setting limits.(4)For 321 kinds of pollutants screened out,the control limits of air pollutants at the enterprise boundary were estimated according to occupational exposure limits and olfactory thresholds in China,and the situation of adopting occupational exposure limits in the United States was compared and analyzed.Among 212 kinds of VOCs,20.8% of the pollutants have an olfactory threshold less than the estimated limit,and among 109 kinds of non-VOCs,only the olfactory threshold of hydrogen sulfide is less than the estimated limit,so the influence of the olfactory threshold should be considered when setting the limits.There are differences in the olfactory threshold and occupational exposure limits from different sources.Therefore,more sources of olfactory threshold data and occupational exposure limits data should be widely collected and their applicability should be analyzed when setting control limits.With the rapid development of China’s economy and the improvement of people’s living standards,the public’s requirements for environmental quality are constantly improving.In order to better protect public health,environmental protection standards and their formulation methods are becoming increasingly strict.The method of establishing the classification of air pollutants and the grading of limit at enterprise boundary proposed in this study can be a positive reference for the revision of relevant standards in the future. |
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