Qualité de l’air à Taichung

What is the level of air pollution in Taichung City?

Taichung, officially Taichung City, is a special municipality located in central Taiwan. It acts as the centre-piece of the Taichung–Changhua metropolitan area, which is the second largest metropolitan area in Taiwan. According to a census conducted in March 2020, Taichung City had an estimated population of approximately 2,816,667 people. This ranks it as Taiwan’s second most populous city.

In the third quarter of 2021, Taichung City was experiencing a period of “Moderate” air quality with a US AQI reading of 59. This United States Air Quality Index figure is calculated by collating the recorded levels of six of the most prolific air pollutants. These may include, both diameters of PM (PM10, PM2.5), nitrogen dioxide, sulphur dioxide, ozone and carbon monoxide. If figures are not available for all six, a level can still be calculated by using what information there is. It is then be used as a metric when comparing one city with another, anywhere in the world. For Taichung City, all six pollutants were recorded which were; PM2.5 - 16 µg/m³, PM10 - 32 µg/m³, ozone (O₃) - 74 µg/m³, nitrogen dioxide (NO₂) - 22.6 µg/m³, sulphur dioxide (SO₂) - 5.2 µg/m³ and carbon monoxide (CO) - 458 µg/m³. The level of PM2.5 can be seen to be one and a half times above the target figure of 10 µg/m³, as recommended by the World Health Organisation (WHO). This is considered to be an acceptable level although no amount of air pollution can be thought of as being safe.

Whilst this level of pollution is not extremely high, the advice would still be to stay indoors as much as possible with doors and windows firmly closed so as to prevent the ingress of more polluted air. Those groups of people who are more sensitive to air pollution should limit their expose to outdoor air and certainly reduce outdoor exercise. There is an app available from AirVisual which can be downloaded to any mobile device which gives up-to-the-minute details about air quality. This should help with that decision.

Does the level of air pollution in Taichung City remain the same throughout the year?

Air quality can be very volatile and can therefore change quickly as dictated by atmospheric and meteorological conditions.

Looking back at the 2020 figures published by IQAir.com, it can be seen that from January until the end of May and from September until the end of December, Taichung City was experiencing “Moderate” air quality with figures between 12.1 and 35.4 µg/m³. The month of August produced “Good” quality air with a reading of 10.3 µg/m³. The remaining months of June and July achieved the WHO target figure of being less than 10 µg/m³. The recorded figures were 7.1 µg/m³ in June and 7.3 µg/m³ in July.

Historically, records pertaining to air pollution were kept since 2017 when the annual average was 20.3 µg/m³. The following year of 2018 saw a slight improvement of 19.2 µg/m³. And again in 2019 another improvement was recorded with a figure of 18 µg/m³. Almost as expected, 2020 saw another decline with a figure of 15.5 µg/m³. However, this figure may have been influenced by the COVID-19 pandemic when many vehicles were not being used as their drivers were asked to work from home and not travel to the office each day. Many smaller factories and production units were also closed which eliminated their emissions from the atmosphere.

Where does the air pollution in Taichung City come from?

Taiwan 's air pollution is mainly divided into two types: domestic generation (such as factories and power plants) and overseas migration (such as mainland China). Among them,66% of PM2.5 pollution comes from domestic.

Taiwan’s Taichung Thermal Power Plant is currently the world’s largest coal-fired power plant with the largest carbon dioxide emissions, and is often regarded as a source of air pollution in central Taiwan. The topography is also an important factor in exacerbating Taiwan’s air pollution. The area around Taichung City is very mountainous and interrupts the smooth flow of air. This is worse in the winter months when pollution can hang in the air for days. Past experience has shown that the haze is prone to occur after the beginning of autumn. Because of the low wind on the ground and the weaker pressure field, there is no strong northern cold air infusion, and the pollutants near the ground are not easy to spread, resulting in a longer time for suspension.

Can anything be done to improve air quality in Taichung City?

Various air pollution control projects are being discussed for the Taichung Thermal Power Plant. Proposals include a series of strengthening measures including the replacement of oil-fired boilers, reduction of mobile pollution sources in Taichung, promotion of the installation of oil fume prevention equipment in the night market catering industry, and installation of rice straw gasification power plants, so as to minimize the occurrence of poor air quality in the central region. In particular, the Taichung Thermal Power Plant has promised to upgrade the pollution emission control equipment of the existing units, and the newly installed units will use natural gas to generate electricity and increase the efficiency of power generation and adopt the best practices.

What effects does this polluted air have on human health?

Air pollution has many potential health effects, ranging from subtle physiological changes in the body to obvious symptoms such as an itchy nose and sore throat, wheezing, coughing, chest pain or chest tightness. Patients with asthma or chronic respiratory diseases will get worse if they are exposed to air pollutants. Although the degree to which different people are affected by air pollution depends on different factors, people of different ages are all affected by poor air quality, and air pollution has a greater impact on children and the elderly and those with pre-existing respiratory problems.

Polluted air can decrease lung function and lead to the development of chronic bronchitis and obstructive lung disease. It can lead to irregular heartbeats and non-fatal heart attacks. For people with pre-existing respiratory problems, it can lead to premature death.

Because of its small size, PM2.5 has the ability to bypass the body’s natural defence system and pass through to the base of the bronchial tubes and into the alveoli where they can then pass into the bloodstream.