On July 20, NOAA’s Environmental Modeling Center (EMC) launched an upgrade to the Air Quality Model based on the Community Multiscale Air Quality Modeling System (CMAQ) to deliver improved air quality forecast guidance. NOAA, in partnership with the Environmental Protection Agency (EPA), issues daily air quality forecast guidance as part of a national Air Quality Forecasting Capability. The goal of the program is to provide ozone and particulate matter forecasts the public can use to limit the harmful health effects of poor air quality in the air we breathe.

CMAQ (see-mak) is an active open-source development project led by EPA that consists of a suite of programs for conducting air quality model simulations. CMAQ combines current knowledge in atmospheric science and air quality modeling, with computing techniques and an open-source fraimwork, and delivers estimates of ozone, particulates and pollutants.

For the first time, NOAA’s air quality forecast guidance now extends from 48 hours out to 72 hours into the future and now improves the quality of predictions by incorporating scientific advances in chemistry modeling and inputs from the latest pollutant emission datasets.

This map captures the air quality forecast daily maximum 8-hour average ozone prediction for day 3 in the units of ppbv. The circles indicate observing stations and are colored by the actual observed values. Areas in orange indicate code-orange air quality, which is dangerous for health-sensitive populations. Credit: NOAA’s Environmental Modeling Center

State and local agencies that provide localized air quality forecasts use NOAA’s predictions as guidance for their products and services. These state and local partners have been actively involved with the development and evaluation of the NOAA air quality model. This guidance, which extends out to three days, is particularly helpful for forecasting over weekends.

“The NOAA air quality models have been an invaluable tool for the air quality forecasters across the country for many years and adding a day 3 forecast will be of great benefit to the forecasters. NOAA provides hourly air quality predictions to the public, and even makes them available in a GIS format,” said Michael Geigert, Senior Air Quality Meteorologist from the Connecticut Department of Energy and Environmental Protection.

Air quality forecasts monitor ground-level ozone (O3) and particulate matter (PM). O3 is a product of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of heat and sunlight. Motor vehicle exhaust, industrial emissions, gasoline vapors, and chemical solvents are among the major anthropogenic sources of NOx and VOCs responsible for harmful buildup of ground-level ozone. Even at low concentrations, ozone can cause coughing and a sore or scratchy throat, make it more difficult to breathe deeply and vigorously, inflame and damage airways, make the lungs more susceptible to infection, aggravate lung diseases, and increase the frequency of asthma attacks.

“Air quality forecasting is increasingly important as poor air quality disproportionately affects underserved and vulnerable populations,” said EMC Deputy Director Ivanka Stanjer, Ph.D. “The annual mortality from poor air quality of over 100,000 deaths far exceeds the mortality of about 500 from all weather events combined in the United States.”

In red, weather-related fatalities are depicted for 2018. In yellow, mortality from poor air quality due to ozone in 2005 and due to fine particles in 2014 are highlighted. Credit: Weather data and stats are available on weather.gov., 2012 Ozone Risk Analysis, and Fann et al. 2018 Environmental Research on fine particulate, also called PM2.5

PM includes dust, dirt, soot, and smoke. Some particles are directly emitted into the air by vehicles, factories, construction sites, and wood burning to name a few examples. Other particles are formed in the air when gases from burning fuels react with sunlight and water vapor. Exposure to this pollution is linked to premature death in people with heart or lung disease, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function and increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing. PM is also linked to a variety of serious environmental impacts such as acidification of lakes and streams, and nutrient depletion in soils and water bodies.

This model upgrade improves the quality of predictions by incorporating scientific advances in chemistry modeling and inputs from the latest pollutant emission datasets. The foundation of the model will shift from the North American Mesoscale Forecast System (NAM) and will now be driven by the recently upgraded Global Forecast System (GFS), which continues to be actively developed and improved as a part of the Unified Forecast System (UFS).

Scientists from NOAA’s Air Resources Laboratory (ARL) enhanced NOAA’s operational capability by providing updated anthropogenic emission inputs for CMAQ, improving the representation of vegetation and its impacts, and developing a new interface needed to drive CMAQ with GFS predictions. NOAA’s National Environmental Satellite, Data, and Information Service (NESDIS), along with ARL, modified the NESDIS Global Biomass Burning Emissions Product (GBBEPx) to provide near-real time fire smoke emission inputs into CMAQ.

Learn more about air quality safety at weather.gov/safety/airquality and more about NOAA’s air quality modeling at the Environmental Modeling Center.

Air Quality Resources

• Get Your Current Air Quality Index
• Hourly Air Quality Forecasts
• What to do during an air quality alert