Greta Jimenez
Daejeon, a city in South Korea, is facing significant air pollution issues, particularly during the winter months. The city's air quality is impacted by various factors, including traffic, the use of heating, and power plants burning fossil fuels. Vehicles, for instance, release nitrogen dioxide (NO2) and sulfur dioxide (SO2), with areas of heavy traffic often showing high levels of nitrogen dioxide. Daejeon's air pollution levels have reached up to 31.6 μg/m³, which is considered 'moderate' pollution, and at times, the levels have been close to the 'unhealthy for sensitive groups' rating. These pollution levels can have immediate and prolonged effects on individuals, especially those with sensitivities. Real-time air pollution maps and indices are available for Daejeon, providing information on specific areas within the city, such as Daeseong-dong and Dunsan-dong.
| Characteristics | Values |
|---|---|
| Location | Daejeon, South Korea |
| Population | 1.5 million (as of 2010) |
| Pollution sources | Vehicle emissions, power plants, factories, open fires/combustion |
| Pollutants | Nitrogen dioxide (NO2), sulfur dioxide (SO2), fine particulate matter (PM2.5, PM10), black carbon, ozone (O3), carbon monoxide (CO) |
| Pollution levels | Vary throughout the year; higher during winter due to increased heating and power demands |
| Recent PM2.5 readings | 8.3-31.6 μg/m³ (late 2020 to early 2021) |
| Air Quality Index (AQI) | 101 (unhealthy) |
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What You'll Learn
Nitrogen dioxide (NO2) and sulfur dioxide (SO2) from vehicles
Daejeon, South Korea, is a major transport hub with a population of 1.5 million. The city is well-connected by road and rail, with the capital city of Seoul just 50 minutes away by high-speed rail. As a major transport hub, the city is subject to numerous sources of pollution, including vehicle emissions.
Nitrogen dioxide (NO2) and sulfur dioxide (SO2) are two of the six primary air pollutants that make up the Air Quality Index (AQI). These gases are released from vehicle exhausts, with nitrogen dioxide being a more noteworthy offender. High volumes of traffic are often directly correlated with high levels of nitrogen dioxide in the atmosphere. The concentration of nitrogen dioxide in South Korea had been increasing but has been decreasing since 2007, indicating that stronger emission regulations are having a positive impact.
In addition to nitrogen and sulfur dioxide, vehicles also emit fine particulate matter, such as black carbon, a major component of soot. This is also released from factories, open fires, and combustion. These pollutants contribute to Daejeon's poor air quality, which has been described as moderate with PM2.5 readings of 31.6 μg/m³ taken at the end of December 2020. While these readings are within the acceptable range, they are still relatively high and can cause health issues for certain individuals.
To improve air quality, Daejeon could implement emission caps or limits in industrial zones, factories, and power plants, with penalties for non-compliance. Additionally, South Korea could phase out fossil fuel use in factories and transition to more sustainable energy sources.
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Fossil fuels used in power plants
Daejeon, a city in South Korea with a population of 1.5 million, has been facing air pollution issues. The city's air pollution is influenced by various factors, including vehicle emissions and the increased use of heating during winter, which leads to higher energy demands and fossil fuel consumption at power plants.
Fossil fuels, such as coal, oil, and natural gas, are commonly used in power plants for electricity generation. These plants are known as fossil fuel power stations, and they play a significant role in providing electrical energy worldwide. The process involves burning fossil fuels to produce heat energy, which is then converted into mechanical energy to power electrical generators. This process is subject to the Carnot efficiency limit, impacting the overall efficiency of the plant.
Coal, being the most abundant fossil fuel, is widely used in thermal power stations due to its availability and affordability. However, it produces more greenhouse gases and pollution compared to equivalent amounts of petroleum or natural gas. The combustion of coal releases carbon dioxide and other gases, contributing to global climate change.
In addition to coal, natural gas and petroleum-based fuels are also utilized in fossil fuel power plants. Natural gas is commonly used in internal combustion engines, while gasoline and diesel oil are alternative options. These fossil fuels undergo a combustion process, generating thermal energy, which is then converted into mechanical energy, and ultimately, electrical energy.
To improve efficiency, multiple generating units may be built at a single site, optimizing the use of land, natural resources, and labor. Fossil fuel power plants are custom-designed systems, and some incorporate a combined cycle power plant design, utilizing both the Brayton cycle of the gas turbine and the Rankine cycle of the heat recovery steam generator (HRSG).
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Fine particulate matter (PM2.5)
Fine particulate matter, or PM2.5, refers to particles in the air that are 2.5 micrometres or smaller in diameter. These particles are so small that they can be inhaled and enter the bloodstream, potentially causing adverse health effects. PM2.5 is primarily caused by the combustion of fossil fuels and has been linked to increased cardiopulmonary mortality and morbidity. That is, exposure to PM2.5 has been associated with an increased risk of developing cardiovascular and respiratory diseases, as well as other health issues.
Daejeon, a city in South Korea, has been identified as one of several metropolitan areas in the country where the hourly PM2.5 concentration has been measured and analysed over a five-year period from 2015 to 2019. This study aimed to identify the best times for ventilation to improve indoor air quality, which is especially critical for vulnerable populations such as children and the elderly who spend extended periods of time indoors.
The findings from this study in Daejeon and other South Korean cities revealed that PM2.5 levels were consistently higher in the spring and winter seasons. During the study period, the PM2.5 levels exhibited a peak between 7 am and 1 pm, with variations in the peak height and declining patterns observed across different regions. While the specific data for Daejeon is not explicitly provided, it is included in the group of metropolitan cities that showed similar patterns in PM10 concentrations, with Incheon and Daegu being the most notable exceptions.
The health effects of PM2.5 have been studied extensively in heavily polluted cities in China, such as Xi'an. Research has found that the combustion of fossil fuels may influence the health impacts associated with PM2.5 exposure. However, the specific chemical constituents within PM2.5 that cause harm to human health remain unknown. China has one of the highest PM2.5 levels globally, yet it is not currently considered a criteria pollutant in the country, and there is a lack of monitoring data on its adverse health effects.
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Respirable particulate matter (PM10)
Respirable particulate matter, or PM10, refers to inhalable particles with diameters of 10 micrometers or less. These particles are considered coarse and can deposit in the upper airways, including the nose, throat, and bronchi. While the health effects of long-term exposure to PM10 are less clear compared to PM2.5, several studies suggest a link between prolonged exposure to PM10 and adverse health outcomes, particularly related to the respiratory system.
The sources of PM10 vary, but they often differ from those of PM2.5. These sources can include construction sites, unpaved roads, fields, smokestacks, and fires. The particles themselves are a complex mixture of solids and aerosols, composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. The chemical composition of PM10 can include inorganic ions, metallic compounds, elemental carbon, organic compounds, and compounds from the Earth's crust.
The health effects associated with PM10 exposure are concerning. In addition to respiratory issues such as asthma, bronchitis, and rhinosinusitis, PM10 exposure has been linked to cardiovascular risks, including an increased likelihood of heart attacks and arrhythmias due to systemic inflammation. Older adults with chronic heart or lung disease, children, and asthmatics are identified as the groups most vulnerable to the adverse health effects of PM10 exposure.
The World Health Organization (WHO) has established guidelines to limit exposure to PM10, recommending an annual mean of no more than 15 μg/m3 and a 24-hour mean of no more than 45 μg/m3. Exceeding these levels increases the risk of adverse health consequences. Notably, the ESCAPE study, involving a large European cohort, found that for every increase of 10 μg/m3 in PM10, the lung cancer rate rose by 22%.
While I cannot provide real-time data on Daejeon's air pollution levels, sources indicate that the city of Daejeon in South Korea experiences prominent pollution issues, especially during the colder months. This is partly attributed to the increased use of heating, which leads to higher energy demands and, consequently, the release of larger amounts of pollutants and chemicals into the atmosphere.
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Carbon monoxide (CO)
Daejeon, the fifth-largest city in South Korea, is a major transport hub with a population of 1.5 million. The city is well-connected by roads, motorways, and trainlines, with the capital city of Seoul just 50 minutes away by high-speed rail. Due to its high connectivity, Daejeon is subject to prominent pollution issues. While there are no specific figures available for carbon monoxide (CO) levels, it is one of the pollutants that is a concern for sensitive individuals.
Daejeon's air pollution readings in late 2020 and early 2021 showed PM2.5 levels up to 31.6 μg/m³, which is considered moderate pollution. While there were a few days with lower readings that met the World Health Organization's (WHO) target goal of 10 μg/m³ or less, these were surrounded by readings averaging 28 μg/m³ and above, particularly during the colder months.
Vehicle emissions contribute significantly to Daejeon's air pollution, releasing contaminants such as nitrogen dioxide (NO2) and sulfur dioxide (SO2). High traffic volumes are often correlated with increased nitrogen dioxide levels. Vehicles also emit fine particulate matter, such as black carbon, which is also released from factories, open fires, and combustion processes.
To improve air quality, Daejeon and South Korea could implement emission caps or limits in industrial zones, factories, and power plants. Enforcing guidelines and holding polluters accountable through fines or threats of closure can help reduce pollution levels. As of May 28, 2025, Daejeon's real-time Air Quality Index (AQI) levels were moderate, ranging from 58 to 103. While these levels are acceptable, certain pollutants like carbon monoxide (CO) may still impact sensitive individuals.
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Frequently asked questions
Daejeon is the fifth-largest city in South Korea and has some prominent pollution issues. Like many cities in the country, it is subject to numerous sources of pollution, including vehicle emissions and the use of fossil fuels such as coal.
Vehicles are a major cause of pollution in Daejeon, as they emit contaminants such as nitrogen dioxide (NO2) and sulfur dioxide (SO2). Nitrogen dioxide is of particular concern, as areas with high traffic volumes often show high levels of this gas in the atmosphere.
The air quality in Daejeon is impacted by the pollution, with the city experiencing high levels of fine particulate matter (PM2.5) and respirable particulate matter (PM10). These pollutants can have negative effects on the health of individuals, especially those with sensitivities.
Meteorological conditions, such as the extreme cold of winter, can worsen Daejeon's pollution. During these periods, the increased use of heating and higher energy demands on power plants contribute to more significant pollution levels.
