Support our mission

SEOUL — August’s barrage of rain may be slowing traffic and canceling outdoor events, but it’s had at least one benefit: the air is cleaner than usual.

During the hot summer months each year, the air in South Korea and particularly its largest cities sees a rise in ozone pollution, which at high levels can harm breathing and irritate skin.

“The rain helps a lot to keep ozone density in the air down,” said Kim Du-rae of the city government’s Research Institute of Public Health and Environment.

However, on sunnier days, ozone pollution worsens.

Seoul activates its ozone alert system from May 1 to Sept. 15, Kim said. Each provincial government tracks ozone levels separately.

Ozone pollution forms in chemical reactions in the atmosphere when nitrogen oxides combine with hydrocarbons, according to the American Lung Association Web site. The added summer heat and sunlight increase levels. Hydrocarbons come from vehicles, chemical plants, refineries, factories, gas stations, paint and other fossil fuel-based processes.

Children and the elderly are particularly susceptible to ozone pollution, according to Kim and the American Lung Association. However, healthy adults also can be susceptible, they say.

Physical training and outdoor classes are restricted at Seoul schools when ozone levels count 0.12 to 0.29 parts per million.

At the warning stage — a density from 0.3 to 0.49 parts per million — outdoor activities from kindergartners through high school are canceled.

Beyond 0.5 parts per million, Seoul will close schools and encourage its people to spend as much time as possible indoors. They also recommend people use public transportation to limit vehicle pollutants, Kim said.

The Seoul government has issued warnings on five days this summer, which is about average, Kim said. The warnings are posted on electric signs on various city streets.

U.S. Forces Korea does not issue ozone alerts nor track ozone as they do the “yellow dust” storms common in the spring.

“While we routinely assess health issues affecting U.S. forces, we do rely on commercial resources to alert us to problems with ozone and automobile pollutants,” USFK spokesman David Ten wrote via e-mail.

Alerts would be sent out if the 18th Medical Command dubbed it necessary, he said.

Some provincial governments in South Korea post ozone levels on their Web sites. Seoul’s Korean language Web site at shows ozone numbers on its home page.

Hwang Hae-rym contributed to this report.

A look at what ozone overexposure can do to you

The American Lung Association and Seoul Research Institute of Public Health and Environment have listed important facts on how ozone may harm the body:

OXIDIZING: Process by which ozone attacks lung tissue by reacting chemically with it.SEASONAL RISK: Levels tend to be worse in the summer because of added heat and sunlight. Cloudy skies can lower levels.INTERNAL BURN: Ozone acts as a powerful irritant at the levels frequently found across the United States, as well as South Korea. Some compare this to getting a “sunburn” on the lungs.MALFORMATIONS: Animal toxicology studies have shown that long-term exposure to high levels of ozone can cause structural changes to the lungs.SHORTER LIVES: Research studies cited on the American Lung Association Web site state that breathing ozone over a short period can increase the risk of premature death. This includes levels found in cities around the U.S., Europe and Asia.WORSE HEALTH: Many areas in the United States and South Korea have enough ground-level ozone during the summer months to cause health problems that can be felt right away. Immediate problems include:

twitter Email

stars and stripes videos

around the web

Sign Up for Daily Headlines

Sign-up to receive a daily email of today’s top military news stories from Stars and Stripes and top news outlets from around the world.

Sign up