(1) Environmental load and trends
End of February 2023, the population of Tainan City was 1.859 million, with a density of 846.2 people/km2, which was higher than national average 644 people/km2, ranking sixth among the six municipalities, and the population has shown a downward trend since 2018.
There are currently a total of 2,447 controlled-list factories in Tainan City, of which plastic products manufacturers account for the largest number (about 18.2%), followed by the metal industry (about 12.4%), and then the gas station industry (about 11.7%). In recent years, the number of construction sites has generally shown an increasing trend year by year, with approximately 10,000-13,000 sites each year.
The total number of vehicles was 2.09 million in February 2023, and the number of vehicles for per person was 1.1, of which scooters account for the majority (65.2%), followed by automobiles for 29.6% and diesel trucks for 5%. The scooter is negative growth, especially the two-stroke scooters have decreased 87.7% from 2013 to February 2023, and the electric scooters have gradually exceeded the two-stroke scooters since 2021. However, the fuel and diesel supply has increased by 10.1% in the past decade.
(2) Air quality analysis
In general, the ratio of air quality index (AQI) of good and ordinary grades (AQI ≤ 100) in Tainan City in the past five years (2018~2022) has shown an increasing trend year by year, rising from 76.4% in 2018 to 90.0% in 2022, and has reaching 80% for three consecutive years, and exceeded 90% for the first time in 2022. And the number of good days reached a record high of 43.7%. The rate of poor air quality index (AQI>100) has shown a trend of improvement year by year, from 23.6% in 2018 to 5.5% in 2022, and the rate of poor AQI has decreased by 58.6%. Among them, the improvement of PM2.5 was the most significant, from 23.6% in 2018 to 9.8% in 2022; O3 -8hr shows a fluctuating trend, however, O3-8hr has improved significantly and the poor air quality ratio was 4.32%, reaching a record low.
In the trend of changes in the concentration of major air pollutants in the past 5 years (2018-2022), the annual average and daily average concentrations of PM10 have been improving year by year. The annual average has improved from 55.7 μg/m3 in 2018 to 33.0 μg/m3 in 2022, with an improvement rate of 40.8%; the daily average has improved from 109.2 μg/m3 in 2018 to 68.6μg/m3 in 2022, an improvement rate of 37.2%, and have also met the newly revised air quality standards (50μg/m3, 100μg/m3) for four consecutive years since 2019. As of March 2023, the annual average of PM10 was 52.2μg/m3, a significant increase of 22.0% compared with 42.8μg/m3 in the same period last year, and the daily average was 92.8μg/m3, increase of 11.8% compared with 83.1μg/m3 in the same period last year. Mainly due to the impact of the dust incident in the upwind river at the beginning of the year.
The annual average and 24-hour average concentration of PM2.5 by manual measurement stations are improving year by year. The annual average has dropped from 23 μg/m3 in 2018 to 17.2 μg/m3 in 2022, with an improvement rate of 25.0%; the 24-hour average decreased from 61.5 μg/m3 in 2018 to 42.0 μg/m3 in 2022, and the improvement rate was 31.7%.
The hourly average and 8-hour average concentrations of O3 show fluctuations, but the overall trend is still decreasing. The hourly average improved 5.4% and declined from 95.3 ppb in 2018 to 90.1 ppb in 2022；8-hour average improved 3.5% and declined from 71.6 ppb in 2018 to 69.1 ppb in 2022.
(3) Air Quality Model Simulation of Ozone Impact Sources in Tainan City
1. According to the simulation results, in the annual means of eight-hour ozone averages, the higher ratio of impact came from mobile sources, with the highest being large trucks, whose impact ratio was 10.1%. The highest impact in non-point sources came from the emissions of agricultural machinery and construction equipment, with an impact ratio as high as 5.4%. It is recommended to strengthen the related control measures or enhance enforcement, including through meetings with the Environmental Protection Administration to suggest the Agriculture and Food Agency to regulate agricultural machinery by means of cross-departmental consultations.
2.In addition to carrying out the model simulation of ozone, the impact ratios of its precursors, such as nitrogen oxides (NOx) and non-methane hydrocarbons (NMHC) for the annual means and different AQI levels, were simulated for different sectors. According to the simulation results, in terms of the total impact ratios of the annual means of eight-hour ozone averages, NOx was the highest (37.9%), followed by NMHC (27.6%), while the remaining pollutants (OTH) accounted for 10.9%. It shows that the Tainan City’s number of poor air quality station days due to eight-hour ozone averages was primarily caused by the main precursor pollutant NOx.
3. In the change of ozone impact ratios in major sectors, when the AQI level rose from ordinary to initial alert, the impact ratio of mobile pollution sources was the largest (four-stroke motorcycles, private gasoline passenger vehicles, and large trucks amounted to approximately 20%). It is recommended to strengthen the inspection efforts for four-stroke motorcycles and large trucks, propose related preferential schemes, encourage the public to take public transportation more frequently, and reduce the use of private vehicles.
(4) Analysis for emission inventory
According to the TEDS 11.0 emissions database and the updated results of this plan, each category of emission sources in Tainan in 2019 are below:
Category TSP PM10 PM2.5 SOx NOx NMHC
Point (tons/year) 739.61 501.33 384.25 1,214.52 2,618.71 3,461.53
Area (tons/year) 40,992.79 11,868.16 2,924.23 325.65 1,505.54 27,875.50
Line (tons/year) 2,958.27 2,040.67 1,634.76 10.91 17,717.92 9,155.20
Total emission(tons/year) 44,690.68 14,410.17 4,943.24 1,551.08 21,842.17 42,202.12
According to the emission inventory in 2019 to analyze the trend of emission changes in the past ten years. Compared with 2010, TSP and PM10 increased by 12% and 1% respectively; while PM2.5, SOx, NOx and NMHC decreased by 18%, 65%, 20% and 8% respectively.
(5) Management Examination Tainan City Air Pollution Control Plan (2020~2023)
Assisted the Tainan City Environmental Protection Bureau (TNEPB) in administering the Tainan City Air Pollution Control Plan (2020 to 2023), with a total of three aspects, 27 control strategies, 60 control goals, and the "Bright Clear Sky Suspended Particulate Reduction Control Plan" for the cross-bureau. The main focus of this edition of the paln is the annual average concentration target of PM2.5 and the reduction target of air pollutants.
Based on the achievement of the annual average concentration target of PM2.5 in Air Quality Basin, the average annual concentration of PM2.5 in Yun-Jia-Nan Air Quality Basin in 2022 was 17.77 µg/m³, which has reached the expected target of 20.6 µg/m³; in terms of pollutant reduction targets, various air pollutants (PM10, PM2.5, SOx, NOx and NMHC) have all reached the planning targets ahead of schedule.
(6) Manage the quality and effectiveness in each air quality control project
1. Executing “2022 Tainan City Air Quality Improvement and Maintenance Plan Management and Evaluation Method”: SIP assisted TNEPB to evaluate the quality and effectiveness of each air quality relative projects.
2. Managements results of each air quality relative projects: “Strengthen the Street Dust Cleaning project” had the highest scores because of the completeness of data reporting and the achievement of Air Pollution Control Plan with high scores. The other hand, “Scooter Exhaust Pollution Inspection and Control Project” had the poor scores because of the goal of Air Pollution Control Plan and the work progress of the EPA's assessment are behind schedule, which affects the overall performance.
3. Grasps the contents of the performance evaluation work of the EPA's air quality improvement work in 2022, and considers the implementation capacity of the relevant committees in the Air Noise Section of TNEPB, and evaluates the estimated score in 2022 of Tainan City’s evaluation of about 108.26 points, and the overall score the rate is 88%.
4. According to the performance evaluation work of the EPA's air quality improvement work in 2022 evaluation results, Tainan city was awarded an excellent result in the evaluation.
(7) Maintenance and management of air quality purification zone
1. The number of air quality purification zone sites increased from 192 in 2011 to 222 in March 2023, a total of 30 sites have been added, with a total area of 50.473 hectares and a length of 72.178 kilometers.
2. In 2022, the total of applications for subsidies were 6 places. After review, the approved application area was 0.329 hectares, and the approved amount was NT$593,252. In addition, a total of 118 purification zone sites applied for maintenance subsidies, with an application rate of 65.4% and an approved amount of NT$2,119,539.
3. In 2022, a total of 216 purification zone bases were assessed. The assessment opinions were fed back to the maintenance units on the bulletin board through the front desk system function of the Tainan Air Quality Purification District website.
4. Assisted in submitting 7 excellent purification zones to participate in the EPA's "Selection and Reward Activity for Excellent Adopting Units in Air Quality Purification Zones". The EPA and experts and scholars conducted an on-site inspection in Tainan City on January 2, 2023. In the end, 6 adoption units won awards.
5. Completed the adoption of 30 purification zones by enterprises, village offices, community development associations, school parent associations or volunteer teams.
6. Assisting 9 junior high school and North District to apply for setting green wall from EPA, with a total installation area of 201.41 m2.
7. In order to improve the quality of maintenance and management of the air quality purification zone, during the working period, completed the diagnosis and treatment of 5 purification zones to achieve the work goals of this year.
(8) Indoor air quality improvement work
1. Completed inspections of 55 sites with sensitive groups, including 17 childcare centers, 24 schools (including kindergartens), 9 social welfare institutions (e.g., nursing homes or parent-child centers), and 5 postpartum care institutions. The inspection visit and questionnaire survey were done at the same time to serve as a reference for subsequent policy implementation.
2. Assisted the Environmental Protection Bureau of Tainan City Government in jointly inspecting 13 public and private venues, conducting a total of 52 inspections. All inspection results complied with indoor air quality standards.
3. Promoted the acquisition of autonomous badges of indoor air quality for a total of 41 venues, including 32 officially announced premises and 9 non-officially announced premises, thereby achieving the Environmental Protection Administration’s assessment goals.
(9) Operation and maintenance of TN EPB automatic and manual monitoring stations
1. According to the requirements of the project contract, 144 sampling for TSP, 11 sampling for component analysis of TSP, 24 dust fall sampling, 144 single-point flow calibrations, 24 multi-point flow calibrations, 1-type first-level flow calibrations, 1 timer calibration and 6-point precision testing for the manual station were completed as scheduled. In terms of the automatic station, 12 station-times monthly maintenance, 6 station-times quarterly maintenance and 2 station-times semi-annual maintenance were completed as scheduled.
2. In the part of the data utilization rate of the automatic monitoring station, the overall data availability rate reached 98%, except for a few periods of time due to equipment failure and inaccessibility of the equipment in the school.
(10) Promotion for Air quality management effectiveness
1. In order to give the public a good impression of the policy and convey the air pollution policy, it is the first in the country to set up the "Tainan City Air Quality Monitoring Network" by this project, to provide a three-day air quality forecast in detail during the poor air season, and also publishes the air quality, weather pattern, wind speed and direction of the day, and other relevant information before am 7:30 every day for providing the public with complete air quality information in a convenient way. In addition, "air quality information display boards" have been set up in three places, including Wenhua village Community Activity Center in the Southern District, the TNEPB's Cangjin Pavilion (Fudong Street) and the Cangjin Pavilion Preparatory Office (Fuqian Road) to provide real-time air quality information for the outdoor public.
2. In order to make citizens feel good about the policy and convey that the city attaches great importance to air pollution-related policies, the EPB has been assisted by this project in issuing 14 press releases and 137 Facebook card posts.
3. Continue to maintain the 30 AQI information push and broadcast systems and Xiaoximen electronic billboards, and publish messages to promote public protection during poor air quality seasons to make air quality information disclosures more transparent.
4. 14 large-scale electronic billboards were rented at important intersections in Tainan City to remind the public of relevant protection messages, contingency measures for air quality deterioration, and promotion of various air pollution management policies of the TNEPB.
