Air Quality Monitoring

National Ambient Air Quality Standards (NAAQS)

The Clean Air Act (CAA) requires the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards (NAAQS) for six criteria pollutants. Ozone and particulate matter are two of these pollutants.  EPA works with partners at state, local, and tribal air quality agencies to meet these standards.  In Michigan they primarily work through the Michigan Department of Environmental Quality (MDEQ).

Under the CAA, as amended in 1990, each state must develop a plan describing how it will attain and maintain the NAAQS.  In other words, how it plans to clean up polluted areas and keep them clean.  This plan is called the State Implementation Plan (SIP) and is required under Section 110 of the CAA (40 CFR Part 51, Subparts F & G).  In general, the SIP is a collection of programs, including:

• a monitoring program, which is a collection of monitoring devices which provide actual measurements of the concentrations in the air, to identify whether an area is meeting the air quality standards
• air quality calculations and computer modeling, which are used to predict future trends and the effects of emission reduction strategies
• emissions inventories, which describe the sources and categories of emissions to the air for a given pollutant, and how much is emitted by each source or source category

Ozone Monitoring

A network of five air quality monitoring stations, located in Evans, Grand Rapids, Holland, Jenison, and Muskegon, continually monitor ozone levels in West Michigan from April 1st through September 30th. The MDEQ and the EPA average the data from these monitors over eight hours and compare it to the NAAQS. At each monitoring station, the fourth highest eight-hour value averaged over three years is not to exceed 75 parts per billion (ppb). If over three years, the average of the highest ozone values is over 75 ppb, the NAAQS is violated.

For a map of these monitoring stations, click here.

Particulate Matter Monitoring

A network of four air quality monitoring stations, located in Grand Rapids, Muskegon, and Allegan County, monitor West Michigan particulate matter levels year-round. The MDEQ and EPA use an annual standard and a daily standard to determine compliance with the particulate matter less than 2.5 um in diameter (PM2.5) NAAQS particulate matter violations. The annual standard is 15.0 micrograms per cubic meter (µg/m³). To attain this standard, the three-year average must not exceed 15.0 µg/m³. To attain the daily standard, the three-year average of the 98th percentile of 24-hour cencentrations at each monitor must not exceed 35 µg/m³.

For a map of these monitoring stations, click here.

Monitoring and Clean Air Action Days

To help protect the health of the community, a Clean Air Action Day will be called on days when widespread ozone concentrations are forecast to exceed 75 ppb over an eight hour period or particulate matter levels are forecast to exceed 35 µg/m³ over a 24-hour period throughout the area.

The Air Quality Index (AQI) is a tool used to communicate air quality to the public that is separate from the ozone and PM2.5 NAAQS. The AQI, normalized by pollutant concentration, ranges from good (green), moderate (yellow), unhealthy for sensitive groups (orange), to unhealthy (red).

For current air quality information, you can view ozone monitors or particulate matter monitors (MDEQ web site) to see real time data from monitoring stations around the state.

Clean Air Action Day Notifications in West Michigan

Previous Ozone Action Day Notifications in West Michigan

More information

Realtime Ozone and Particulate Matter Data – view current ozone and particulate matter information from MDEQ air monitoring sites.

Air Quality Standards (NAAQS) for Ozone and Particulate Matter – find out what air quality levels are used to define "clean air" for ozone and particulate matter under the Federal Clean Air Act.

Designations for Ozone and Particulate Matter – find out if a geographic area you are interested in meets clean air standards for ozone or particulate matter.

Regulatory Actions for Ozone and Particulate Matter – find EPA links to proposed and final rules, fact sheets, and other rulemaking documents.

Controlling Particle Pollution – find information, and links to information, on work that is underway to reduce particles in the air, both by reducing directly emitted particles and by reducing emissions of pollutants that are gases when emitted but which form particles in the atmosphere.

The West Michigan Clean Air Coalition is a partnership of businesses, academic institutions, government agencies, industry, and non-profit organizations in Kent, Ottawa, Muskegon, and Kalamazoo counties working together to achieve cleaner air in the region through the education and promotion of voluntary emission reduction activities.