Committed to protecting its citizens against harmful effects of ozone, the Seoul Metropolitan Government introduced the ozone warning system. Under the system, citizens can get detailed information on the ozone level of the day, and the system is especially useful to patients with respiratory diseases, senior citizens and children who can be affected by exposure to high ozone concentration. The system also encourages citizens to take voluntary measures to reduce the ozone concentration in the atmosphere.
 

The ozone level of Seoul in 1995 stood at 0.013ppm, exceeding the 0.1 PPM standard, then dropped to the lowest on record in 2013 to 0.022ppm. Also, the public showed a concern over the correlation between ozone concentration and respiratory diseases among the elderly and children. Against this backdrop, the ozone warning system was first initiated by the Seoul Metropolitan Government in 1995 to issue a warning when the ozone density exceeds a certain level in order to minimize the health risks associated with the ozone. Currently, 66 local and municipal governments nationwide adopted the ozone warning system. Since the ozone density is higher from May to September, Seoul introduced the Ozone Forecast System since 1999 to alleviate the citizens’ concerns and encourage voluntary participation in case the government advices the citizens to refrain from unnecessary driving.
Initially, 25 administrative districts of Seoul were classified into four districts (Northeastern, Northwestern, Southeastern, and Southwestern districts). However, Jongno-gu, Jung-gu, and Yonsan-gu which were originally part of the Northwestern region were reclassified as the Central district in 2011. Accordingly, there are five major districts under the current system.
 

Ozone Warning System
Based on Article 8 of Clean Air Conservation Act, the ozone warning system is implemented from May 1st to September 15th every year. Depending on the ozone concentration in the atmosphere, one of three stages of ozone warning is issued; ozone alert for 0.12ppm/hr or higher, ozone warning for 0.3ppm/hr or higher, and ozone grave warning for 0.5ppm/hr or higher concentration. Taking into account the geographical characteristics of Seoul and the travel route of air pollutants, 25 administrative districts of Seoul are classified into five districts: Central, Northeastern, Northwestern, Southeastern, and Southwestern district. If the measurement at one of the monitoring stations exceeds the criteria to issue a warning, the government reviews the weather condition, then issues the warning in that district.
 
Ozone Alert Situation Room
Each local government operates an Ozone Alert Situation Room from May to September. During this period, the situation room is operated from 12pm to 6pm everyday, including weekends and holidays. If an ozone warning is issued during one’s shift, the public servant is required to be on standby until the warning is lifted. When the ozone warning is issued, the respective local government takes necessary measures to minimize the hazardous effects of high ozone concentration.
 
Promptly Notifying the Risks of High Ozone Concentration
If the ozone concentration is forecasted above 0.081ppm/hr as of 6pm, the city government informs power-generation plants, incineration plants, and painting facilities that emit large amounts of NOx and VOCs to lower the operation rate of facilities on the next day. If the ozone warning is issued, the city government will immediately notify 23,106 institutions and facilities, and 150,000 citizens who signed up to receive ozone warning text messages. In order to minimize the negative health risks arising from high ozone levels, citizens will be advised to refrain from driving their cars and encouraged to take public transportation.
 
Minimizing the Sources of Ozone Pollution
During the summer season, the city government advises power plant operators that emit large amounts of nitrogen oxide to reduce operating hours and encourages painting facilities and gas stations to operate shorter hours during the day time to reduce the ozone concentration. If the ozone level is below ‘poor,’ the city government deploys water sprinklers to clean the streets during the day time. In addition, inspections of heavily polluting vehicles, decrepit vehicles, and trucks are provided for free to curb the emission of ozone precursors.