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Background of Air Quality

A. The definition of air quality index

Air quality index based on monitoring data will be on the same day in the air ozone(O3), fine particulate matter(PM2.5), particulate matter(PM10), carbon monoxide(CO), sulfur dioxide(SO2) and II Nitric oxide(NO2) such as the concentration of value, its impact on human health, were converted into different pollutants The vice-value targets, indicators, deputy to the day of the maximum value of the stations on the day of the air quality index (AQI).

The concentration of pollutants and air quality index value deputy table
The concentration of pollutants and air quality index value deputy table

1.Areas are generally required to report the AQI based on 8-hour ozone values. However, there are a small number of areas where an AQI based on 1-hour ozone values would be more precautionary. In these cases, in addition to calculating the 8-hour ozone index value, the 1-hour ozone value may be calculated, and the maximum of the two values reported.

2.8-hour O3 values do not define higher AQI values (≥ 301). AQI values of 301 or higher are calculated with 1-hour O3 concentrations.

3.1-hour SO2 values do not define higher AQI values (≥ 200). AQI values of 200 or greater are calculated with 24-hour SO2 concentrations.

B. Current status of air quality

The 2022 statistics for Taiwan's Air Quality Index (AQI) show that the percentage of days with AQI>100 (indicating substandard air quality) was 6.4%, while the percentage of days with "good air quality" was 59.6%. Before air pollution control fees were levied in 1994, the percentage of days with PSI (Pollutant Standards Index) >100 was 7.0%. Since December 2016, the new air quality index (AQI) has been in use, while use of the original PSI was ceased in 2017. In 2014, PM2.5 manual stations were deployed, the statistics for which show the percentage of station days with AQI>100 has decreased from 26.2% in 2014 to 6.4% in 2022. These figures clearly indicate that the nation's air quality in recent years has been greatly improved and that efforts to control air pollution have paid off.

Schematic diagram of the article

C. Air quality management measures

(1) Air quality improvement objectives

To reach the same air quality standards as advanced countries and to improve overall air quality, the MOENV has set the objectives of reducing the percentage of days with AQI>100 by 2016 to below 20%, and:

  1. a. Short-range objective by 2020: below 15%
  2. b. Mid-range objective by 2025: below 11%
  3. c. Long-range objective by 2030: below 7%

Based on current situations and forecasts of air quality concentrations, we need to further reinforce control measures or tighten standards for fugitive particulates and ozone precursors, in addition to existing control measures and programs. The MOENV will take gradual steps to adopt a total quantity control system, enforce stricter standards, advocate the use of clean fuel oil, and promote green products as well as public transportation.

(2) Air quality zoning management

Based on geographical and meteorological conditions and the nature of air contaminants, the MOENV has divided the nation into seven Air Quality Zones—northern Taiwan, Jhu-Miao area, central Taiwan, Yun-Chia-Nan area, Kao-Ping area, Hua-Dong area, and Yilan—and announced Total Quantity Control Zones accordingly. Due to air quality in central Taiwan and the Kao-Ping area, priorities are given to these areas to enforce control measures and improvement programs and to set up annual air quality improvement objectives.

(3) Total quantity control system tasks:

  1. a. Establish air quality standards
  2. b. Establish an effective air quality monitoring station network
  3. c. Designate air quality zones and phase-in proclamation of total quantity control zones
  4. d. Draft and enforce total quantity control plans and air pollution control programs
  5. e. Divide air quality zones into compliance and non-compliance zones according to the status of air quality
  6. f. Enforce total quantity reduction in those zones not in compliance with air quality standards; allow pollutant increase limits in those zones in compliance with air quality standards
  7. g. Promote an emission saving, exchanging and trading system with economic incentives

(4) Air pollutant emissions data inventory

In order to improve air quality and investigate air pollutant emissions across Taiwan, the MOENV established a national air pollutant emissions inventory in 1992, the “Taiwan Emissions Data System (TEDS)”. The scope of TEDS covers the estimation of emissions from various regions of the country (22 counties/cities in total) and various sources and industries, including fixed pollution sources (point sources such as factories, public and private places); area sources (commercial activities, daily living activities, construction activities, agricultural activities, and non-human activities such as river dust, coastal dust, hillside dust, forest fires, etc.); mobile pollution sources (line or road sources such as passenger cars, buses, trucks, scooters, etc.); non-road sources (such as trains, ships, airplanes and agricultural/construction machines, etc.); and biological sources (VOC emissions from photosynthesis in forests). The TEDS is updated every three years, based on a general review of estimation methodology and calculation of a new base year, and is partially updated for historical years. The latest version of TEDS is TEDS 11.1 with the base year of 2019.

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