To further improve air quality in Taiwan, the EPA plans to tighten the air quality standards and lower the daily average PM10 limit to 100 µg/m3, and the maximum one-hour average of SO2 concentration to 0.075 ppm. In addition, the EPA will also impose stricter standards for NO2 and lead.
The Air Quality Standards were last amended on 14 May 2012, in which both the annual and 24-hour PM2.5 concentrations were added to strengthen PM2.5 control. To enhance air quality improvement, the EPA plans to lower the daily average PM10 limit from 125 µg/m3 to 100 µg/m3 and reduce the annual average limit from 65 µg/m3 to 50 µg/m3. Moreover, the EPA will lower the maximum one-hour average SO2 concentration from 0.25 ppm to 0.075 ppm and the annual average concentration from 0.030 ppm to 0.020 ppm. As for the NO2 standards, the maximum one-hour average NO2 concentration will be brought down from 0.25 ppm to 0.1 ppm and the annual average from 0.050 ppm to 0.030 ppm. Lastly, the air quality standard for lead will be set at 0.15 µg/m3 as a rolling three-month average concentration.
According to the air quality guidelines (AQG) published by the World Health Organization (WHO) in 2005, the interim target values for the 24-hour PM2.5 concentration and the annual mean PM2.5 concentration are set at 25 μg/m3 and 10 μg/m3, respectively. The interim targets are provided to encourage air quality improvement and to reduce adverse health effects posed by PM2.5 emissions. However, the WHO did not set a fixed threshold for PM2.5 and the interim target values provided are relatively lenient. Hence, the EPA won’t change the air quality standards for PM2.5.
The WHO suggested that national air quality standards should be set based on factors such as health risks caused by local air conditions, current pollution sources, technological feasibility, and social and economic development. The WHO also provided three interim target values for both the 24-hour PM2.5 concentrations (75, 50, 37.5 μg/m3) and the annual mean PM2.5 concentrations (35, 25, 15 μg/m3).
The US first established its PM2.5 standards in 1997, which originally set the 24-hour concentration at 65 µg/m3 and the annual mean concentration at 15 μg/m3. The standards for the 24-hour concentration were then tightened to 35 μg/m3 in 2006, and the annual standard was lowered to 12 μg/m3 in 2012. Even though the annual standard finally dropped from 15 μg/m3 to 12 μg/m3 after 15 years of adjustments and efforts, most states were still unable to reach the tightened standard of 12 μg/m3. South Korea started implementing an annual PM2.5 standard of 25 μg/m3 in 2015. Singapore currently does not maintain air quality standards for PM2.5, but a goal of reaching an annual mean concentration of 12 μg/m3 by 2020 has been set. Thus, Taiwan enforces stricter PM2.5 standards compared to other western and Asian countries.
From the Clean Air Action Plan promulgated in 2015 to the Air Pollution Control Action Plan, the EPA has shown its devotion to control of PM2.5 and its precursors. According to the data collected by manual monitoring devices, the annual average PM2.5 concentration in 2017 was 17.5 μg/m3, which was an improvement over the previous three years.
Excerpt from Environmental Policy Monthly, 22 (8)
- Environmental Protection Administration, R.O.C.(Taiwan)