Air quality in Yuanlin

Does Yuanlin have a high level of air pollution?

Yuanlin is a city located in Changhua County, Taiwan, home to some 124,000 inhabitants within the county-administered city. In recent years, Yuanlin has come in with some poor readings of air quality, with yearly averages placing it amongst the top most polluted cities within Taiwan, as well as being in the upper echelons of the worlds most polluted cities.

As an example of continuing levels of high air pollution, in late May of 2021, Yuanlin presented with a US AQI reading of 158, a sizeable number that placed it within the ‘unhealthy’ air quality ratings bracket. When measured by the US AQI scale (which itself is an aggregated number formed from the volume of several main pollutants found in the air), any reading between 151 to 200 is counted as being unhealthy, with a color coding of red, which can be seen in both the air quality maps and graphs present throughout the IQAir website. These color codings are also shown when looking at pollution readings from years past (although these are generally measured in PM2.5, one of the most dangerous forms of pollution present in the atmosphere).

This reading of 158 brings with it an elevated risk of vulnerable individuals experiencing adverse health effects, with pulmonary and cardiac conditions being aggravated as a result of exposure to such polluted air. The general public may also start to experience irritation to their respiratory tract, with a number of other conditions making themselves present if said exposure is not halted, or at least limited.

Those who fall into the ‘at risk’ demographic include pregnant women, who’s unborn children may be subject to a myriad of highly negative health effects if prolonged exposure continues. These include alterations to the nervous system, resulting in babies being born prematurely, with a low birth weight, possible mental or physical impairments, along with a higher risk of miscarriage, thus raising the infant mortality rate.

Other vulnerable groups include the elderly and infirm, as well as those with pre-existing health conditions or compromised immune systems (with the two often being interchangeable). Young children and babies are also highly vulnerable, much in the same vein as how unborn babies are affected, with those who are going through their important formative years being extremely susceptible to alterations or disruptions to their nervous system. The large amount of fine particles in the air can cause inflammation of the airways, leading to reduced lung function, stunted growth and cognitive impairment, as well as the development of life-long issues such as asthma or various forms of skin disease or rashes.

Other readings of US AQI that were present over the course of May 2021 were one such as 87 and 91, which were on the lower end of the pollution readings in Yuanlin. These came in under the ‘moderate’ pollution bracket, requiring a reading of 51 to 100 to be classified as such, and color coded as yellow (exactly the same when compared to the PM2.5 ratings that will be discussed soon). Other readings that came in slightly higher were ones such as 111 and 129, in the ‘unhealthy for sensitive groups’ bracket, color coded as orange, as well as requiring a reading of anywhere between 101 to 150.

As per the guidelines set out by the US Environmental Protection Agency, any reading between 0 to 150 is ‘acceptable’, however, on the higher end of this scale, some negative issues may start to appear. In closing, Yuanlin is subject to some high levels of air pollution, both from years past and continuing well into 2021.

Why does Yuanlin have heightened levels of air pollution present?

Yuanlin sees much of its air pollution generated from sources such as domestic combustion, with the burning of materials such as charcoal and firewood all adding to the high pollution readings. Furthermore, the topographical layout of much of Taiwan is known to be conducive for trapping pollutants within it, leading to them being unable to disperse, due to the many high mountains surrounding a majority of cities.

The burning of fossil fuels in factories, power plants and other related industrial areas or businesses contributes further to the year round ambient levels of pollution, along with fumes and exhaust emissions from cars and heavy freight vehicles such as lorries and trucks. Whilst combustion of fossil fuels and other materials make up the majority of air pollution in Yuanlin, there is also the issue of large amounts of dust clouds, or ‘fugitive dust’ as it is more commonly known, being blown into the cities from rural areas, often stemming from landslides and earthquakes, thus creating large amounts of fine particles that can become part of the PM2.5 and PM10 collective when they accumulate within Yuanlin.

What are some of the main types of pollution found in the air in Yuanlin?

The main pollutants found in the air would be the ones that are seen in the calculation of the overall US AQI level, which include ozone (O₃), nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). Ultrafine (PM2.5) and coarse (PM10) particles are also a major issue in Yuanlin and Taiwan as a whole, being found high up in the atmosphere, as well as on ground level.

Other pollutants include ones such as black carbon and volatile organic compounds (VOCs), both of which are formed from the combustion of fossil fuels and other organic materials. Silica dust and finely ground gravel or earth would also be considered as some of the more prominent pollutants within Yuanlin.

When does Yuanlin have its worst pollution episodes?

Looking at the PM2.5 levels on record as taken in 2020, it can be seen that the months of January, November and December had the highest levels of PM2.5, although not by significant amounts. This indicates that the ambient level of air pollution in Yuanlin is poor enough to give it its high yearly average, as opposed to other cities around the world that have certain months with huge spikes in their pollution levels, followed by periods of much cleaner air quality.

The months mentioned above came in with PM2.5 readings of 37.6 μg/m³, 38.2 μg/m³ and 37 μg/m³ respectively, making November the most polluted month of the year.

At what time of the year is Yuanlin at its most free from air pollution?

Whilst the whole year of 2020 did not see any months that had any prominent drops in the pollution levels, the period of time from February all the way through to October all came in with ‘moderate’ readings of air pollution, requiring a reading of 12.1 to 35.4 μg/m³ to be classified as such, as per the PM2.5 ratings system.

Out of all of these months, May had the cleanest reading, coming in at 22.5 μg/m³, followed closely by August and March which both had the same reading of 23.3 μg/m³.