Study On Comprehensive Evaluation Method Of Ambient Air Quality In Consideration Of Odor Pollutants

With the rapid development of industrialization and urbanization in China, air pollutants are continuously increasing. The scope of pollution is expanding gradually. People pay more attention on ambient air quality problem. In the field of environmental protection, there are numerous substances that can cause air pollution. It’s not comprehensive to attribute the cause only to some specific contaminants. Therefore, we need to consider the influence of various air pollutants on environment when assessing ambient air quality and evaluate the impact synthetically. The odor pollution, a kind of environmental pollution which human beings are very sensitive, is an important respect in influencing residents’ satisfaction with air quality. However, the evaluation of odor pollutants (such as NH3, H2S, benzene series) develops slowly in the environmental air quality assessment system of our country. How to assess ambient air quality more comprehensively has become an important issue which needs to be resolved urgently.Based on the existing air quality evaluation system, a method of assessment was built in this paper to reflect the actual regional ambient air quality by taking odor pollutants into consideration. It put forward an odor index grading scheme in accordance to odor threshold, health effect and international standards of some odorous substances. Public odor complaints were also considered. First, according to the unique geographical conditions, surrounding industries and the distribution of pollution sources, we chose several typical odor pollutants. Referred to relevant standards at home and abroad, the olfactory threshold of different odor substances and health effect research results of pollutants, the paper determined level 3 concentration limit about the odor factors, set and classified each factors’odor index by the method of index classification. On this basis, combined with actual situations and data availability, we took AQI, odor index, target rate, Pi, odor complaint intensity as evaluation indicators and defined each indicator’s grading standard in accordance with their effects on air quality. Then, a new air quality synthetic assessment index system combined with odor factors was established, which could get more comprehensive and reasonable results. Finally, in the light of the excessive situation about the contaminants that exceed standard over different time scales, we analyzed the causes and provided theoretical foundation and scientific guidance for the formulation of air pollution control measures.We took the Xianqi Area in Jiangsu Province as a case to conduct the study and chose 6 odor pollutants, ammonia, hydrogen sulfide, benzene, toluene, xylene and NMHC, as the odor factors. According to the method proposed in this paper, we evaluated air quality in this region synthetically. The results showed that air quality in this region became worse significantly in 2013. There always existed that air quality was not up to standard during the year. In most of the period when air quality doesn’t reach the standard, especially hydrogen sulfide. Hydrogen sulfide exceeded standard seriously in summer, autumn and winter. The circumstance was more evident during the season alternation. The excessive frequency of hydrogen sulfide at night was more than that during the day and the enterprises may prefer discharging at night. The research revealed that the method could help to improve the national air quality evaluation system and have some certain application value.