(1) Environmental load and trends
In March 2021, the population of Tainan City was 1.879 million, with a density of 857 people/km2, which was higher than national average 652.16 people/km2, ranking sixth among the six municipalities, and the population has show n a downward trend since 2018.
There are currently a total of 2,426 controlled-list factories in Tainan City, of which plastic products manufacturers account for the largest number (about 16%), followed by the metal industry (about 13%), and then the gas station industry (about 11%). In recent years, the number of construction sites has generally shown an increasing trend year by year, with approximately 12,000-13,000 sites each year.
The total number of vehicles was 2.012 million in 2020, and the number of vehicles per person was 1.07 per person, of which scooters account for the majority (65.4%), followed by automobiles for 29.3% and diesel trucks for 5%. The scooter is negative growth from 2011, especially the two-stroke scooter has decreased 81.7% in the past decade. The fuel and diesel supply has increased by 10.4% 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 (2016~2020) has shown an increasing trend year by year, rising from 69.7% in 2016 to 84.4% in 2020, a record high. The rate of poor air quality index (AQI>100) has shown a trend of improvement year by year, from 30.3% in 2016 to 15.6% in 2020, and the rate of poor AQI has decreased by 14.7%. Among the percentage of poor air quality of the index pollutant PM2.5 was declined from 23.9% in 2016 to 5.5% in 2020；O3 -8hr shows a fluctuating trend. In recent years, due to the significant reduction in the proportion of poor AQI-PM2.5 and O3-8hr has not improved significantly, the main indicator pollutant has been converted from PM2.5 to O3-8hr.
The ratio of poor air quality (AQI>100) from January to April of 2021 shows a deteriorating trend compared with the same period of past year. The main reasons for the deterioration include the increase in overseas pollution and in weather patterns that are not conducive to the diffusion of pollutants compared with the same period of last year, which has led to the increase in the percentage of poor air quality in Tainan City and whole country.
In the trend of changes in the concentration of major air pollutants in the past 5 years (2016-2020), the annual and daily average concentrations of PM10 fluctuated in the first two years and improved year by year in the next three years. The annual average has improved from 50.7 μg/m3 in 2016 to 37.8 μg/m3 in 2020, with an improvement rate of 25.4%; the daily average has improved from 109.5 μg/m3 in 2016 to 75.7 μg/m3 in 2020, with an improvement rate of 30.9%. The average and daily averages have also met the newly revised air quality standards (50 μg/m3, 100 μg/m3) since 2019.
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 26.1 μg/m3 in 2016 to 18.3 μg/m3 in 2020, with an improvement rate of 30%; The 24-hour average decreased from 65 μg/m3 in 2016 to 51 μg/m3 in 2020, and the improvement rate was 21.5%.
The hourly average and 8-hour average concentrations of O3 show fluctuations, but the overall trend is still decreasing. The hourly average improved 13% and declined from 108 ppb in 2016 to 93.8 ppb in 2020；8-hour average improved 0.5% and declined from 75.3 ppb in 2016 to 74.9 ppb in 2020
(3)Air quality deterioration notification and related achievements
A.Executing notification system of AQI>100: The amounts of notification was 126 days (504 site-days) which established Inter-Bureau Response Team for 15 times (The response team lasted for 20 days up to 1 time, 3 days up to 2 times, 2 days up to 5 times, and removed 7 times after the establishment of the day.) After executing response, the proportion of AQI below forecast was 74% and the proportion of AQI above forecast was 26%. Which indicated that executing response was effective for improving air quality.
B.Based on the conclusions of the Inter-Bureau Response and simulation drill meeting: “Tainan City Air Quality Deterioration Prevention Measures Plan” had modified to strengthen Air Quality Control Command Center’s ability of emergency work.
(4)Analysis for emission inventory
According to the TEDS 10.0 emissions database and the updated results of this plan, each category of emission sources are below:
Category TSP PM10 PM2.5 SOx NOx NMHC
Point (tons/year) 2,040.67 1,342.62 995.07 2,101.98 2,700.51 15,724.43
Area (tons/year) 23,306.56 8,104.25 2,175.71 671.13 1,605.25 19,748.20
Line (tons/year) 3,155.25 2,253.82 1,830.13 382.78 20,742.39 10,404.95
Total emission
(tons/year) 28,463.69 11,661.91 4,969.24 2,786.33 24,707.01 45,877.58
(5) Model simulation analysis for the influence of the source of ozone in Tainan city
In order to understand the source of influence of ozone concentration in Tainan City, Community Multi-Scale Air Quality (CMAQ) model was used to simulate the contribution ratio of various emission sources on O3 concentration in Tainan City, including native sources within Tainan City (point, line, and area source), emission sources of neighboring counties and cities (Yunlin County, Chiayi County and City, Kaohsiung City), other emission sources of Taiwan (other counties and cities and marine vessels), as well as sources outside Taiwan. Taiwan's emissions are based on TEDS10.0, and the simulation periods are March, April, May, September, October, and November of the months of high ozone concentration in Tainan City in 2016.
According to the results of the simulation, the highest contribution on ozone concentration in Tainan City was from long-range transport (outside of Taiwan), the other source with a higher contribution was from trans-boundary pollution outside of Tainan City and marine vessel emissions. Among the neighboring counties and cities, the emission sources of Kaohsiung City have a greater impact on Tainan City’s ozone. In terms of the native sources in Tainan City, the impact of line source emissions on ozone is relatively high, and its contribution ratio exceeds more than half of the total contribution ratio of pollution sources in Tainan City. However, some of area sources are also mobile pollution sources. Therefore, to control ozone in Tainan City, the focus should be on mobile pollution sources as the primary goal.
(6)Developed Air Pollution Control Plan of Tainan City (2020-2013, Draft)
To achieve the Executive Yuan’s Air Pollution Control Plan (2020 to 2023) and air quality vision goals of Tainan City: Air pollutant PM10 and PM2.5 will be improved from the current three-level control zone to the second-level control zone, the maximum hourly ozone concentration value will be maintained in the second-level control zone, and the target of annual average PM2.5 concentration of 19.7 ug/m3 in Yun-Chia-Nan air basin has to be reached in the 2023, this project formulated “Air Pollution Control Plan of Tainan City (2020 to 2023, Draft)”, which includes 27 control strategies and 60 control targets. Based on the Executive Yuan’s Air Pollution Control Plan (2020 to 2023), and combined with "Bright Clear Sky Suspended Particulate Reduction Control Plan" that has carried out for long-standing and cross-bureau to expand the line to area to achieve the overall target of Tainan City.
The Environmental Protection Agency (EPA) has not formally approved the TN City Air Pollution Control Plan (2020-2023, Draft), but this project still reviewed with the draft submitted to the EPA review. The current implementation of the 2020 air pollution control plan targets are in line with the overall target, and both the PM2.5 concentration target and the various air pollutant emission reduction targets have reached the expected targets. This project will continue to conduct rolling reviews and revisions in accordance with the review of the relevant opinions of EPA on TN Air Pollution Control Plan.
(7)Manage the quality and effectiveness in each air quality control project
1. EPA assessment results review: According to the evaluation results announced by EPA in 2020, Tainan City won "Top Award in Air Quality Management", which indicated that Tainan’s work has been affirmed by EPA and committee.
2. Executing “2020 Tainan City Air Quality Improvement and Maintenance Plan Management and Evaluation Method”: SIP assisted Tainan to evaluate the quality and effectiveness of each air quality relative projects.
3. Managements results of each air quality relative projects: “Construction Site Pollution Control Plan” had the highest scores because of the completeness and timeliness. The other hand, “Stationary Pollution Permit Review And Inspection Control Management Plan” had the poor scores because it was behind schedule.
4.Grasps the contents of the performance evaluation work of the EPA's air quality improvement work in the year 2021, and considers the implementation capacity of the relevant committees in the Air Noise Section of the Environmental Protection Bureau, and evaluates the estimated score of the city’s 2021 years of evaluation of about 98 points, and the overall score the rate is 87%.
(8) Operation and maintenance of TN EPB automatic and manual monitoring stations
1.According to the requirements of the project contract, 24 sampling for TSP, 1 sampling for component analysis of TSP, and 24 dust fall sampling were completed as scheduled; 144 single-point flow calibrations, 24 multi-point flow calibrations, 1-type first-level flow calibrations, 6 timer calibration and 24-point precision testing；The manual station part also completed the automatic station monthly maintenance 12 stations, 6 stations quarterly maintenance and 2 stations semi-annual maintenance as scheduled, and in accordance with the relevant regulations of the Environmental Protection Agency’s Chief Accounting Office Fill in the sampling results form.
2.A third party was entrusted to carry out the functional inspection of TN EPB automatic monitoring stations (Chengxili station, Nanxi station), and the satisfaction rate of each check item was 100%.
3.In the part of the data utilization rate of the automatic monitoring station, the overall data availability rate reached 99.8%, except for a few periods of time due to equipment failure and inaccessibility of the equipment in the school.
(9)Maintenance and management of air quality purification zone
1.The number of air quality purification zone sites increased from 192 in 2011 to 237 in 2020, with a total area of 78.914 hectares and 71.072 km.
2.In 2020, the total of applications for subsidies were 7 places. After review, the approved application area was 0.418 hectares, and the approved amount was NT$88,473. In addition, a total of 129 purification zone sites applied for maintenance subsidies, with an application rate of 67.8% and an approved amount of NT$2.687,082.
3.In 2020, a total of 224 purification zone bases were assessed. After the initial evaluation by this project, 12 bases were shortlisted for the year-end evaluation by experts and scholars, including 4 tree planting and community green belts in the school district; 4 environmental protection parks; 4 environmental protection forest park avenues. Finally, 4 excellent purification zones were selected. Accepted the Mayor’s commendation on December 23, 2020.
4.Assisted in submitting 6 excellent purification zones to participate in the EPA's "Selection and Reward Activity for Excellent Adopting Units in Air Quality Purification Zones". All 6 sites were shortlisted for awards, and the number of awards was the first in the country.
5.Promote the adoption and maintenance of purification zones in districts, communities and enterprises. Adopting units have increased year by year. In 2020, 204 bases have been adopted by private units, with an adoption rate of 86%. In addition, 6 purification zones have been diagnosed and treated to reach the work target for this year.
6.Assisting 12 school to apply for setting green wall, 4 green wall applications were approved by EPA, including 3 elementary schools and 1 junior high school, with a total installation area of 92 m2 and an approved amount of NT$429,000.
(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 that the city government attaches importance to, this project assisted in the publication of Facebook, picture cards, and posts, a total of 27 articles have been published.
2.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.
3.During the season of poor air quality, 16 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 TN EPB.
