Taipei, Aug. 12 (CNA) The concentrations of PM2.5 particulates in Taiwan's industrial parks were higher in 2017 than the previous year, but it may not have been because of more pollutants being spewed into the air, according to data compiled by the Environmental Protection Administration (EPA).
The EPA has air quality monitoring stations in five of Taiwan's industrial parks, and four of them showed higher average concentrations of airborne particulate matter smaller than 2.5 micrometers (PM2.5) last year than a year earlier.
Wu Sheng-chung, head of the EPA's Department of Air Quality Protection and Noise Control, told CNA that the poorer air quality in industrial parks resulted from less rainfall in 2017 rather than the generation of more pollutants.
"A higher density in PM2.5 concentration doesn't necessarily mean increases in pollution because it is affected by wind, temperature, and rainfall," Wu said, citing the example of the monitoring station in Qianzhen (??) in Kaohsiung.
It recorded an average PM2.5 concentration of 29.5 micrograms per cubic meter in 2017, up 6.4 ug/m3 from 2016, the biggest increase of the five stations in industrial parks.
But Wu said the concentration of sulphur dioxide (SO2) and nitrogen dioxide (NO2) -- which can trigger PM2.5 particulates -- averaged around the same levels in Qianzhen last year compared to a year earlier, suggesting no year-on-year change in the amount of pollutants emitted.
A decrease of 1,852 millimeters in rainfall around the area during the same period was therefore a contributing factor to higher concentrations of PM2.5 because there was less rain to wash away the airborne particles, he said.
Wu said similar forces were at work in the increases in average PM2.5 concentrations recorded at the monitoring stations in Toufen, Mailiao and Taixi in 2017.
The annual average PM2.5 concentrations obtained at the monitoring station in Mailiao (??) in Yunlin County in west-central Taiwan was 27.8 ug/m3, an increase of 2.4 ug/m3 compared to the previous year.
Another station in Taixi in Yunlin registered an increase of 0.8 ug/m3 to 25.7 ug/m3.
In Toufen in Miaoli County, the PM2.5 concentration averaged 20.1 ug/m3 last year, 1.8 ug/m3 higher than the station recorded in 2016.
The only monitoring station in an industrial park where the concentration of PM2.5 particulates fell was in Xianxi in Changhua County. It was down 1.9 ug/m3 in 2017 from a year earlier to 24.4 ug/m3.