The tested results such as the insulator salt density, the speed of sulfation etc. show that air pollutant elements are the main reason for increasing network insulator salt density.

• 绝缘子盐密值、硫酸盐化速率等测试结果表明，工业和民用燃煤、石油所排放的大气污染元素是造成绝缘子盐密值升高的主要因素。