Comparison of the Application of Three Methods for the Determination of Outdoor PM 2.5 Design Concentrations for Fresh Air Filtration Systems in China.

With the increasing popularity of fresh-air filtration systems, the methods of determining the outdoor PM _2.5 design concentration have become more important. However, the monitoring of atmospheric fine particles in China started relatively late, and there are relatively few cities with complete data, with obvious regional differences, which led to many problems in the selection of air filters for fresh-air filtration systems. In this paper, three methods of determining outdoor PM _2.5 design concentration were analyzed using the daily average concentration of PM _2.5 in 31 provincial capital cities from 2016 to 2020. Six typical cities in different regions were also taken as examples. The advantages and disadvantages of the three existing statistical methods were compared and analyzed, as well as the corresponding differences in the selection of outdoor PM _2.5 concentration value on the filter systems. The results showed that the method of mathematical induction was more accurate and reasonable for the calculation of outdoor PM _2.5 design concentrations. The local outdoor PM _2.5 design concentration could be quickly calculated using the recommended coefficient K and annual average PM _2.5 concentration of the region, especially for small and medium-sized cities without monitoring data. However, the recommended coefficient K should be provided based on the specific region, and should be divided into values for strict conditions and normal conditions during use. This would provide a simple and effective way to select the correct air filters for practical engineering.