我国南北方城市空气环境质量对比分析

依据国家环境监测部门公布的空气环境质量日报，对27个省会城市、4个直辖市城市的2004年-2006年空气质量数据进行分析。结果显示：我国城市空气污染指数（API）时空差异明显，冬、春季节API值高于夏季和秋季，北方城市的API均值高于南方城市；PM10是大气环境的主要污染物，作为首要污染物出现所占比例南、北方城市分别是66．64％和83．97％；SO2为首要污染物所占比例南、北方城市分别是7．28％和6．19％；北方城市平均Ⅰ级和Ⅱ级天数所占百分比之和为77．00％，重污染级天数所占比例达到1．02％；南方城市平均Ⅰ级和Ⅱ级天数所占百分比之和为87．24％，重污染天数所占百分比是0．04％；城市空气质量优、良天数呈增加趋势。

Comparative Analysis on Cities' Ambient Air Quality in South and North China

Based on daily air quality monitoring data issued by the Environmental Monitoring Division of China,the ambient air quality of 31 provincial capital cities from 2004 to 2006 was analyzed in this paper.The results indicated that air pollution index(API) indicated obvious spatial and temporal variability.The API value in winter and spring was higher than that in summer and autumn,and the mean API value in the northern cities of China was higher than that of the southern cities.PM10 was the principal pollutant in most cities.In the past 3 years,the days with PM10 as predominant pollutant accounted for 66.64% of the whole year in the southern cities and 83.97% in the northern cities;the days with SO2 as predominant pollutant accounted for 7.28% of the whole year in the southern cities and 6.19% in the northern cities.In the northern cities,the percentage of excellent(levelⅠ: API<50) and good(levelⅡ: API 50-100) air quality days was 77.00% of the whole year,and serious pollution(levelⅤ: API>300) rate was 1.02%.In the southern cities,the percentage of excellent(levelⅠ: API<50) and good(levelⅡ: API 50-100) air quality days was 87.24% of the whole year,and serious pollution(levelⅤ: API>300) rate was 0.04%.In general,the percentage of excellent and good air quality days had an increasing trend.