The U. S. Environmental Protection Agency in cooperation with the National Weather Service has developed a National Air Quality Forecasting System to provide timely forecasts of ozone, particulate matter, and other pollutants to prevent or reduce adverse effects of these hazards. The planned capabilities of the modeling system can be divided into the initial phase, the medium-term plan, and the long-term plan. The initial phase is to develop and validate 1-day forecasts of ozone (O3) for the Northeastern US, and to expand nationwide within 5 years. The medium-term (5-7 years) plan is the development and deployment of a nationwide capability to forecast particulate matter concentration for particulate size less than or equal 2.5 microns (PM 2.5). In the long term plan (within 10 years), the forecast range of the air quality system will be extended to 48-72 hours and include a broader range of pollutants.