Air Quality In Missouri: Reporting Pollutants

Missouri's air quality is monitored by the Missouri Department of Natural Resources, which operates a network of air monitors located throughout the state. These monitors help to determine whether areas in Missouri are meeting the National Ambient Air Quality Standards (NAAQS) set by the EPA to protect human health. The state's air quality has improved over the decades, but Missouri still faces challenges due to its diverse geography and seasonal variations. The main sources of air pollution in Missouri include power plants, industrial facilities, mobile sources such as cars and trucks, and agricultural activities such as livestock rearing. The state has implemented plans to address emissions and reduce air pollutants, with a focus on protecting public health and meeting federal air quality standards.

The Missouri Department of Natural Resources' air monitoring network

The Missouri Department of Natural Resources (DNR) works to maintain the purity of the state's air to protect the health and general welfare of the people. The department issues permits to facilities to control air pollution, monitors air pollutants, formulates rules, and enforces laws to maintain air quality.

The DNR operates a network of about 50 ambient air monitoring sites across Missouri. The main purpose of this air monitoring network is to determine whether areas in the state are meeting the primary National Ambient Air Quality Standards (NAAQS). These standards are set by the EPA to protect human health. Data from the monitoring network are sent to the EPA’s national Air Quality System (AQS) database. The network also helps develop information on air quality for Missouri's citizens. Concentrations of most air pollutants are measured continuously, with hourly averages reported.

In addition to the basic required monitoring sites, called State and Local Air Monitoring Stations (SLAMS), Missouri also operates special-purpose monitors (SPM). For example, for short-term air quality studies or instrument evaluation, and to monitor trends in concentrations of toxic air pollutants at a site in St. Louis as part of the National Air Toxics Trends Sites (NATTS) network.

In addition to the monitoring done by the state, some industrial facilities in Missouri conduct air monitoring near their facilities. This monitoring follows quality assurance requirements reviewed and approved by the state, and site operation and instrument performance at these sites are periodically reviewed (audited) by the state. These industrial sites are also identified in the annual monitoring network plan.

The Clean Air Act

Missouri has been working to improve its air quality since the passage of the St. Louis City smoke ordinance in 1937. The Clean Air Act, which addresses a group of 187 hazardous air pollutants, plays a key role in these efforts.

In Missouri, the Department of Natural Resources' Air Pollution Control Program administers the state's air conservation law. This involves issuing air emission permits, inspecting facilities, receiving emissions data, and monitoring air quality to ensure compliance with federal and state regulations. The department also develops state implementation plans to address the six criteria air pollutants: ozone, sulfur dioxide, nitrogen dioxide, carbon monoxide, lead, and particulate matter.

To track air quality and pollutant levels, Missouri operates a network of monitoring stations, including State and Local Air Monitoring Stations (SLAMS) and special purpose monitors (SPM). These stations measure concentrations of most air pollutants continuously, reporting hourly averages. The data collected is sent to the EPA's Air Quality System (AQS) database, contributing to the National Ambient Air Quality Standards (NAAQS) established by the EPA to protect human health.

In addition to the state's monitoring efforts, some industrial facilities in Missouri conduct air quality monitoring near their sites, adhering to quality assurance requirements set by the state. These sites are also included in the annual monitoring network plan, and their data is reported to the AQS database. When an area is found to be not meeting air quality standards, a plan is developed to address the emissions contributing to the issue, with support from industries and citizens to reduce emissions.

Missouri's electricity generating sector

Missouri's electricity-generating sector is a major contributor to the state's air pollution. In 2010, the sector emitted over 5 million pounds of harmful chemicals, accounting for 54% of state pollution and about 2% of toxic pollution from all US power stations. The state's coal-fired power plants are a significant source of these emissions, with Missouri being the 15th worst state in the nation for exposing residents to toxic air pollutants from these plants.

Missouri has a rich history of coal mining, dating back to the 1880s. While coal production has declined significantly since its peak in 1984, the state still has one operating surface mine that produces coal for industrial use. This coal is primarily used for electricity generation, with Missouri having the fourth-highest share of in-state electricity generated from coal among all states. In 2023, the state burned about 24 million tons of coal for electricity generation, the second-highest in the nation after Texas.

The residential sector in Missouri is the largest consumer of electricity, accounting for almost half of total power sales. Additionally, about 40% of Missouri households rely on electricity as their primary energy source for home heating, and 95% of households have electric air conditioning equipment. The state's moderate climate, with infrequent extreme temperatures, contributes to its high energy consumption in the residential sector. The transportation and commercial sectors also play a significant role in energy usage, each accounting for about one-third of the state's total energy use.

To address air pollution from the electricity-generating sector, Missouri has implemented various measures. The state's Department of Natural Resources has approximately 50 air monitors located throughout Missouri, including in St. Louis, to track concentrations of ozone and other pollutants. The department also operates special purpose monitors (SPM) in addition to the basic State and Local Air Monitoring Stations (SLAMS). Missouri follows the federal Clean Air Act, which sets National Ambient Air Quality Standards (NAAQS) to protect public health and welfare. These standards are established by the EPA and focus on six criteria air pollutants: ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), lead (Pb), and particulate matter (PM2.5 and PM10).

Air quality forecasting

Missouri has been working to improve its air quality since the passage of the smoke ordinance in St. Louis City in 1937. The Missouri Department of Natural Resources operates an air monitoring network to determine whether areas in the state are meeting the primary National Ambient Air Quality Standards (NAAQS) set by the EPA to protect human health. The data from this network is sent to the EPA's Air Quality System (AQS) database, which also receives data from industrial facilities that conduct their own air monitoring.

The Clean Air Partnership is known for its daily air quality forecasting in the St. Louis area during the summer months. It uses a colour-coded system to inform residents about ozone pollution levels and their potential health effects. On days with high readings on the Air Quality Index, residents are advised to limit their time spent outdoors, especially if they have respiratory issues or are sensitive to certain pollutants. They are also advised to keep their windows and doors closed and avoid high-traffic areas.

The Missouri Department of Natural Resources has approximately 50 air monitors located throughout the state, including in St. Louis, to monitor concentrations of ozone and other air pollutants. Ozone is formed when pollutants emitted by cars, power stations, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight. Motor vehicle exhaust is a significant source of nitric oxide, which contributes to ozone pollution.

In addition to the basic required monitoring sites, Missouri also operates special-purpose monitors (SPM). The state also addresses 187 hazardous air pollutants that are not covered by federal ambient air quality standards. Instead, federal rules establish emissions standards and requirements for sources of hazardous air pollutants, with national emission standards for 174 categories of sources.

The state develops plans to address emissions that contribute to poor air quality when an area does not meet the standards. Tracking the amount of pollutant emissions by regulated facilities is one way Missouri monitors improvements in air quality. Emissions from power plants and industrial sources are only part of the picture, as mobile sources such as cars and trucks, and non-point sources like residential and light commercial fuel combustion, also contribute significantly to air pollution in urban areas.

The Air Quality Index

Missouri has been working to improve its air quality since the passage of the smoke ordinance in St. Louis City in 1937. The state's air quality is monitored by the Missouri Department of Natural Resources, which operates a network of air monitors located throughout the state, including in St. Louis. The main purpose of this network is to determine whether areas in Missouri are meeting the primary National Ambient Air Quality Standards (NAAQS) set by the EPA to protect human health. The data collected by this network is sent to the EPA's Air Quality System (AQS) database.

Missouri faces unique air quality challenges due to its diverse geography and climate. The state's electricity-generating sector, including coal-fired power stations, is a significant source of air pollution, emitting more than 5 million pounds of harmful chemicals in 2010, which accounted for 54% of state pollution. The agricultural nature of Missouri also contributes to air pollution, with livestock rearing farms producing large volumes of slurry that can pollute the underground water table.

To address air pollution, Missouri has implemented various measures, including the Clean Air Partnership, which provides daily air quality forecasts for the St. Louis area during the summer months. The state also operates special purpose monitors (SPM) in addition to the basic State and Local Air Monitoring Stations (SLAMS). Missouri monitors long-term air toxics trends at a site in St. Louis City and has a permitting program for major sources of hazardous air pollutants. The state develops plans to reduce emissions when an area is found to not meet air quality standards, and industrial facilities are required to conduct air monitoring near their facilities following quality assurance requirements set by the state.

Frequently asked questions