The environment ministry said Wednesday it will begin nationwide forecasts of fine dust levels this week as part of efforts to cope with the continued inflow of harmful particles from China.

The forecasting service, which has been tested in Seoul and its adjacent areas since August, aims to prevent health issues caused by high-density air pollution by informing the public of pollution levels before the environment is affected.

The government will expand the service nationwide from Thursday when related laws are set to go into effect, the ministry said.

Fine dust is defined as particles smaller than 10 micrometers, and if inhaled, it can cause various respiratory diseases and undermine the body's immune system.

The dust report will provide information on air quality on a scale of one to five -- good, so-so, slightly bad, bad and very bad -- based on the average concentration of fine dust. The forecasts will be issued twice a day, even when there is no air pollution, according to the ministry.

Elderly citizens and children are advised to refrain from outdoor activities when the level is "slightly bad" or higher.

These forecasts will become available through official weather reports and Airkorea, the website run by the state-run Korea Environment Corp., to provide information on air pollution levels in real-time.

The ministry will also conduct a pilot program for forecasting ultrafine dust and ozone gases in May, with a plan to officially introduce the system nationwide next January.

Ultrafine dust is composed of particles 2.5 micrometers or less in diameter. Exposure to the dust can cause more serious health effects as it can penetrate the respiratory system further than the larger particles of fine dust, according to experts. (Yonhap News)