جودة الهواء في Daegu

What is the air quality index of Daegu?

Daegu, or to give it its official name, Daegu Metropolitan City is a large city in South Korea. It has the third-largest metropolitan area with over 2.5 million residents and can be found on the south-eastern part of the country, approximately 80 kilometres from the coast.

At the beginning of 2021, Daegu was experiencing poor air quality which was classified as “Unhealthy for sensitive groups” with a US AQI figure of 111. The levels of pollutants were recorded as follows: PM2.5 - 39.5 µg/m³, PM10 - 145 µg/m³, ozone (O₃) - 40 µg/m³, nitrogen dioxide (NO₂) - 56.4 µg/m³, sulphur dioxide (SO₂) - 10.5 µg/m³ and carbon monoxide (CO) - 801.5 µg/m³. With levels such as these, the advice is to close doors and windows to stop the ingress of dirty air and people of a sensitive disposition are advised to wear a mask when venturing outdoors until the air quality improves. Running an air purifier will help if there is access to one. When comparing figures for the main cities in South Korea, they all suffer from poor quality air in January, February and March.

What is the main source of Daegu’s polluted air?

As usual, in most cities throughout the world, the main source of air pollution is caused by vehicle emissions followed by emissions from industry and then road/construction dust. In order to make a difference to the air quality in the city centres, vehicles need to be restricted so as to reduce their emissions. Subsidies could be offered to persuade residents to change their vehicle to an electric-powered one. The use of public transport should also be encouraged. These modern city buses are often powered by electricity or some other clean, sustainable fuel.

Is air pollution in Daegu getting better or worse?

If the predicted concentration of ultrafine dust in the atmosphere is above a certain level, “Emergency Reduction Measures for Highly Concentrated Fine Dust*” are implemented which is a system that restricts the operation of Class 5 vehicles in order to reduce the concentration of ultrafine dust in the short term.

This happens when ultrafine dust or PM2.5 in the air exceeds a certain concentration, it is a measure to improve air quality in a short period of time, mainly issued in winter and spring when the quality of air dips below the acceptable limit.

A push service is available on smartphones to warn drivers of the imminent reduction measures. It is hoped that after this introduction in December 2019, air quality in Daegu will improve.

Electric vehicles, solar vehicles, hybrid vehicles and hydrogen-electric vehicles are excluded from the regulations because of their acceptable levels of emissions if any.

The Daegu province has the lowest precipitation compared to other large cities, so the air cleaning effect by rain is relatively low, and it is also in a basin-shaped terrain surrounded by mountains, which makes it difficult for the pollution to be carried away by the wind.

Under these circumstances, the improvement rate of fine dust in 2011 compared to the average for the three years of 2008-2010 was 9.6 per cent, compared to 6.0 per cent in Busan, 3.5 per cent in Incheon, 8.5 per cent in Gwangju, 4.3 per cent in Daejeon, and 0.0 per cent in Ulsan. Among the six metropolitan cities, it showed the greatest improvement in air quality.

This is analysed as a result of constantly pursuing extensive air quality improvement projects such as the expansion of green spaces and the suppression of dust emissions on construction sites and roads. The supply of natural gas buses (LNG), expansion of vehicle exhaust filters, and constant control of automobile exhaust gases have also helped considerably.

What can be done to improve the air quality in Daegu?

In order to contribute to the improvement of air quality through the early scrapping of vehicles that are ageing and generating a lot of smoke, particularly diesel vehicles, the Early Disposal of Old Diesel Vehicles Subsidy Support Project was implemented. Heavy-duty vehicles include dumper trucks, concrete mixer trucks and concrete pump trucks. Class 5 emission vehicles or construction machinery manufactured before 2005 whose emissions do not attain the acceptable level are also eligible. Some older diesel cars that have not been equipped with emission reduction devices or converted to low-emission engines through government subsidies are also eligible.

As part of the operation of the clean road system, a fixed sprinkling facility was installed in March 2011 to remove dust flying up from the roads of Daegu Subway Line 2 including Dalgubeol-daero, a main arterial road network which contributed significantly to the reduction of PM10.

What is the air quality like on Daegu’s subway system?

The quality of air on the subway system was examined between October and December last year in the carriages of the Daegu city train lines 1, 2 and 3. As a result of examining the indoor air quality, it was revealed that the indoor air quality was very good for all three routes, with nothing to worry about.

In an indoor air quality test, ultrafine dust or PM2.5 and carbon dioxide (CO₂), which are the indoor air quality management items of public transport vehicles, were measured four times during congestion and non-congestion periods.

As a result of the test, the average concentration of ultrafine dust PM2.5 during the congestion period was 11.8 μg/m³ for Line 1, 10.4 μg/m³ for Line 2, and 7.4 μg/m³ for Line 3, much lower than the standard which is recommended to be 50 μg/m³ or less.

The average concentration of carbon dioxide (CO₂) during the congestion period of which the ventilation is appropriate is 1,084 ppm (parts per million) for Line 1, 1,716 ppm for Line 2, and 1,089 ppm for Line 3, all below the recommended level of 2,500 ppm or less.

Conversely, the indoor air quality of public transportation vehicles was changed to fine dust PM10 and carbon dioxide to ultrafine dust PM2.5 and carbon dioxide with the revision of the “Indoor Air Quality Management Act” last year on 3^rd April 2020. The standard was also reduced from 150 ~ 200 μg/m³ of fine dust PM10 to 50 μg/m³ of ultrafine dust PM2.5 similar to general multi-use facilities.