Ambient Air Monitoring

The Air Quality Branch (AQB) operates a network of air monitors throughout Linn County.  These monitors continuously measure pollutants in the outdoor air to track pollution trends over time, show whether outdoor air meets federal air quality standards, and help us determine if the air is healthy to breathe.  

What Pollutants are Monitored?

The Clean Air Act (CAA) of 1970 identified six common air pollutants of concern, called criteria pollutants.  The criteria pollutants are carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide.  Criteria pollutants are the only air pollutants with national air quality standards that define allowable concentrations of these substances in ambient air.  

Exposure to these substances can cause health effects, environmental effects, and property damage.  Health effects include heart or lung disease, respiratory damage, or premature death.  Environmental effects include smog, acid rain, radiation, and ozone depletion. 

AQB's network is tailored to focus on criteria pollutants that have a higher likelihood of threatening public health.  These include particulate matter, ozone, and sulfur dioxide in Linn County.  

How Does AQB Determine the Location of a Monitor?

Placement of air monitors is determined consistent with federal air monitoring rules using population trends, reported emissions inventory data, local meteorological data, and if available, existing air monitoring data for a given area.  In addition, AQB may prioritize monitor placement in areas with potential air quality issues, or to address local air quality concerns.

How Does AQB Ensure the Quality of the Monitoring Data?

AQB uses a variety of measures to ensure its air monitoring data is of the utmost quality.  Air monitors are assessed daily to verify their operations remain within proper specifications.  AQB personnel physically visit each monitoring station on a weekly basis to conduct various quality control checks and preventative maintenance activities.  The monitoring instruments themselves must meet rigorous sampling and analytical requirements prescribed by federal air monitoring rules and undergo daily, weekly, and quarterly quality control checks to verify the instrument calibration, accuracy, and precision.  In addition, independently calibrated instruments are used to perform quarterly and annual audits of the air monitors and their operation.

Air quality data is submitted to the U.S. Environmental Protection Agency and shared with the public on our Current Air Quality page, where users can see real-time concentrations, print reports, and download ambient air monitoring data collected at our monitoring stations.

Air Quality Now!


Related Links:

SHL:  Outdoor Air Quality (

Iowa DNR:  Ambient Air Monitoring (

EPA:  Air Quality Data Collected at Outdoor Monitors Across the US (

Click here for AirNow Air Quality Index Basics.
Click here to learn about pollution trends in Linn County.
Click here to learn 48 simple ways to help reduce air pollution (pdf).
Click here for the current air quality in Linn County.
Click here to sign up for air alerts in Linn County.

What Health Effects are Associated with Air Pollution?

Exposure to air pollution can cause both short-term and long-term health effects.  At elevated levels, all pollutants that the Air Quality Branch monitors (particulate matter, ozone, sulfur dioxide, and toxics) cause shorter-term health effects, such as, but not limited to, eye and airway irritation, chest pain, coughing, shortness of breath, and wheezing.  Additionally, individuals with asthma may experience an increase in frequency of asthma attacks.

Elevated levels of fine particulate matter are also linked to heart problems, such as irregular heart beat, nonfatal heart attacks, or premature death in individuals with pre-existing heart conditions.

Toxics sampling encompasses many different compounds, each with associated health risks.  Some toxics compounds cause, or are suspected to cause, cancer, affect the nervous system and brain function, or reduce fertility and cause birth defects. 

Over time, breathing air with poor air quality can cause lung tissue damage and reduce lung function.  To reduce your risk of experiencing these health effects, avoid extended periods of time outdoors and outdoor exercise during times of elevated air pollution.