An odor is a substance in the air that is smelled or sensed by our nose. Odors can be pleasant or unpleasant. Fragrant and aromatic are words used to describe pleasant odors, while stench and stink are typically used to describe unpleasant odors.

Environmental odors are usually smelled outdoors, but sometimes you notice them indoors too. Many everyday things can cause odors, like food, cleaning supplies, paint, gasoline, air fresheners, flowers, and cut grass. 

Environmental odor sources may include: 

• agricultural practices (fertilizers/pesticides)
• animal farms
• manufacturing facilities
• food processing plants
• landfills
• petroleum refineries
• wastewater treatment facilities 

Sometimes. There are certain groups of chemicals that produce odors are potentially harmful and may cause health problems. However, an unpleasant smell does not necessarily mean it is harmful. Strong unpleasant odors may be a “warning” sign of potential risks to human health rather than a trigger of health effects. Odors from environmental sources might cause health symptoms in some people depending on the individual and other environmental factors.

Health effects from exposure to odors may be an immediate (acute) health risk, a long-term (chronic) risk, or pass quickly once the odor is gone (transient). Getting sick from odors depends on:

• What type of odor you are exposed to,
• How much you are exposed to (concentration),
• How long you are exposed (duration),
• How often you are exposed (frequency), and
• How sensitive you are to the odor or the cause of the odor.

Individuals respond differently to odors. One person may smell and recognize an odor; while at the same concentration, another person may barely notice it.

People have differing sensitivities to odors. Sensitive groups are more likely to experience health impacts. Sensitive groups include children, pregnant women, the elderly, and people with chronic health problems. People with chronic health problems include persons with asthma, emphysema, Chronic Obstructive Pulmonary Disease, and other respiratory diseases.

Symptoms may vary depending on your sensitivity to the odor. The type and concentration of the odor will influence potential symptoms as well.

Common symptoms include:

• Headaches
• Nasal congestion
• Nausea
• Cough
• Eye, nose, and throat irritation
• Wheezing or shortness of breath
• Sore throat
• Chest tightness
• Dizziness

Odors may also affect a person beyond physical symptoms. Odors may also affect a person’s behavior or mood. Exposure to unpleasant odors may also be stressful and lead to stress-related symptoms.

The Clean Air Act and Michigan’s Air Pollution Control Rules limit harmful air pollution, mainly by regulating industrial emissions through permits and rules. Some odors come from sources the Air Quality Division (AQD) doesn’t regulate. When someone files an odor complaint, the AQD uses Rule 901 to decide if it’s a violation.

Rule 901 prohibits the release of an air contaminant that causes:

• Injurious effects to human health or safety, animal life, plant life of significant economic value, or property”
• “Unreasonable interference with the comfortable enjoyment of life and property”.

Rule 901 applies to all regulated sources regardless of whether or not a permit is required.

When you file an odor complaint, an air quality inspector may investigate by observing and documenting the smell. They evaluate it using three factors:

• Frequency – How often it happens (all the time, certain times of day, daily, or once a week).
• Intensity – How strong it is, rated on a scale from 0 (no odor) to 5 (overpowering and intolerable).
• Duration – How long it lasts (minutes, hours, or all day).

These factors help determine if the odor violates Rule 901.

It’s best to stop odors before they start. This often happens through the air permitting process, which can require odor-control equipment to be installed when a facility is built. If an industry is known to produce strong odors, the permit may require the odor to be captured and treated before it’s released. The type of control used depends on the substance causing the smell.

Submit a complaint online in MiEnviro Portal.

Call your local district office

For an environmental emergency: 

Call the Pollution Emergency Alert System (PEAS) hotline at 800-292-4706.

General questions: Call the Environmental Assistance Center at 800-662-9278.