Koreans are exposed to four major air pollutants, including fine dust and ozone, simultaneously for about half a month each year. That means so-called "composite air pollution," in which multiple pollutants exceed standards at once, occurs more often than expected.
A research team led by Im Jeong-ho, a professor in the Department of Urban and Environmental Engineering at Ulsan National Institute of Science and Technology, developed an artificial intelligence (AI) model called DeepMAP that estimates ground-level concentrations of major air pollutants on an hourly basis and displays them like a map, and on the 30th released an analysis of East Asian air quality from 2021 to 2023 using the model.
Fine dust and ultrafine dust can penetrate deep into the bronchi and lungs and worsen respiratory diseases, and nitrogen dioxide, which mainly arises from vehicle exhaust and combustion, can cause decreased lung function and inflammation. Ozone serves as a protective shield blocking ultraviolet rays in the stratosphere, but at the surface it acts as a strong oxidant that strains the respiratory and cardiovascular systems. Recently, studies have also found that when such substances enter the human body simultaneously, they can be more deadly to health than exposure to a single substance.
DeepMAP, developed by the team, combines data from the Geostationary Environment Monitoring Spectrometer (GEMS), an atmospheric chemistry transport model, numerical weather prediction–based meteorological data, and ground observations. With this, it can simultaneously produce hourly concentrations of six air pollutants, including fine dust, ultrafine dust, nitrogen dioxide, ozone, carbon monoxide, and sulfur dioxide.
The analysis found that across East Asia there was widespread occurrence of multiple pollutants simultaneously exceeding the World Health Organization's (WHO) short-term guidelines. In particular, in Korea, days when four pollutants—PM10, PM2.5, nitrogen dioxide, and ozone—exceeded standards at the same time averaged 15 days a year.
According to the team, such composite pollution was pronounced not only in Korea but also in China. The North China Plain saw 24 days a year, and the eastern region recorded 19 days. Composite pollution was concentrated mainly in March and April and in October. The team explained that this reflects seasonal characteristics: lingering effects of winter heating, the addition of spring yellow dust, and active ozone formation under high-pressure systems in autumn.
The strength of the newly developed model is its high spatial and temporal resolution. With a relatively dense spatial resolution of 10 kilometers, it can closely identify regional pollution patterns, and because hourly analysis is possible, it can also track when pollution worsens and in which direction it changes.
Professor Im said, "Previously, analyses of air pollution often focused on individual substances, making it hard to fully reflect real-world situations where multiple pollutants act at the same time," and added, "This model enables a more realistic assessment of composite air pollution and can be used in a wide range of areas, including air quality forecasting, environmental policymaking, and public health research."
The findings were published on the 20th (local time) in the international environmental journal Environmental Science & Technology.
References
Environmental Science & Technology (2026), DOI: https://doi.org/10.1021/acs.est.5c15772