Frequently Asked Questions (FAQ)
What are environmental odors?
Environmental odors are substances in the environment which can be smelled. You typically smell these odors when you are outdoors and sometimes when you are indoors with your windows open. Sometimes people can smell and may react to certain chemicals in the air before they are at harmful levels. Those odors can become a nuisance and bother people, causing temporary symptoms such as headache and nausea. Other odors can be toxic and cause adverse health effects.
Where do environmental odors come from?
Environmental odors can come from many sources such as animals, human activities, industry, nature, and vehicles. Examples of those sources include
- Animals: confined animal feeding operations (CAFOs)
- Human activities: compost, sewages, garbage, fires, household cleaning agents
- Industry: oil refineries, landfills, paper mills, wastewater treatment plants
- Nature: moist soil, gardens, fires
- Vehicles: diesel exhaust
Will environmental odors make me sick?
Some people are more sensitive to environmental odors than others. They may react negatively to environmental odors even at low concentrations. Here are some general principles:
- When the concentration of an odor in air is below levels of irritation and the person is moved out of the exposure area, the symptoms will pass.
- When the concentration of an odor in air is at or above levels of irritation and the exposure duration is longer, the symptoms may last.
Symptoms vary based on the person’s sensitivity to the odor. In most cases, symptoms will depend on the type of substance, its concentration in air, how often exposure occurs (frequency), how long exposure lasts (duration), and the age and state of health of the exposed person.
Young children, the elderly, and pregnant women may be more sensitive to odors. In general, the most common symptoms are
- Nasal congestion
- Eyes, nose, and throat irritation
- Hoarseness, sore throat
- Chest tightness
- Shortness of breath
- Heart tremors (palpitations)
- Mental depression
These symptoms generally occur at the time of exposure. Their intensity will depend on the concentration of the odor in air and how often and how long exposure lasts.
Can my health be negatively affected by environmental odors in my neighborhood?
Some people are more sensitive to environmental odors than others are. When you are more sensitive to the odors, you may have symptoms even at a low concentration of the odor in air. Once the odor stops, or you are separated from the odor, the symptoms usually go away.
Are all environmental odors toxic?
No. Toxicity depends on the amount of a substance (concentration) in the air that people are breathing, how often (frequency) they are breathing that air, and how much time (duration) they spend breathing that air.
If the right conditions exist such as concentration, frequency, and duration, the odor can be toxic and cause adverse health effects.
If those conditions do not exist, odors are generally not toxic.
But some people are sensitive to environmental odors at low concentrations of a substance in air. The length of exposure is important in both cases.
Are environmental odors regulated in the United States?
In general, no. The U.S. Environmental Protection Agency (EPA) regulates pollutants in outdoor air through the National Ambient Air Quality Standards (NAAQS). The NAAQS regulates:
- Carbon monoxide (CO)
- Lead (Pb)
- Nitrogen dioxide (NO₂)
- Ozone ( Oɜ)
- Particulate Matter (PM) and
- Sulfur dioxide (SO₂).
Sulfur dioxide is the only regulated air pollutant with a strong, pungent odor.
Under the Clean Air Act, EPA must control 187 hazardous air pollutants, also known as toxic air pollutants or air toxics. Those chemicals are controlled for their toxicity, not for their odor. They are controlled at the source that generates the emissions. See the EPA website for more information: http://www.epa.gov/ttn/atw/pollsour.html
Environmental odors are not nationally regulated in the United States. But many cities and local governments have established nuisance odor regulations. You can find more information by contacting your city or county health department or your state environmental department.
Can I petition ATSDR to ask for an evaluation of environmental odors in my neighborhood?
ATSDR develops public health consultations about hazardous waste sites or facilities. There is a process to petition ATSDR, but ATSDR needs available environmental sampling data typically gathered by the EPA or a state environmental regulatory agency to conduct an evaluation.
Learn more about
- How community members and government agencies can petition ATSDR
- ATSDR mandates
- What ATSDR can and can’t do to help communities
How do I know what it is I smell?
Visit the What is that odor? section of the website where you can look up an odor and find the substance(s) that produce that odor. You can also look up a specific substance and find a description of the substance's odor.
What can ATSDR do to help with environmental odors in my neighborhood?
If ATSDR is working in your neighborhood to assess environmental exposures, the agency can help by doing one or more of the following:
- Working with the facility producing the odors or regulators to
- Recommend changes in operational time. For example suspending or reducing the odor-producing operations during the time(s) of day or week when the odors are worse (as seen in the odor diaries).
- Recommend ways to reduce emissions. Examples include planting trees, modify engineering techniques, increasing stack height, or changing filters more frequently
- Providing environmental health education to primary care providers in the area
- Recommending personal actions to reduce exposure such as
- Staying indoors when environmental odors are strong
- Exercising indoors on bad odor days
- Leaving the area for a few hours
What can a community like mine do to help itself?
- You can organize to assess the effect environmental odors have on your community.
- You can appeal to local government for policy changes.
- You can appeal to industry to make operational changes to reduce odors.
Odor diaries can help distinguish odor types and times of the day or night when odors are worse. See our Air Pollution Odor Diary webpage for more information about odor diaries.
I have asthma. Can environmental odors make my asthma worse?
In many instances, yes, odors can make asthma worse. Using your inhaler, staying indoors, or leaving the area for a few hours can help.
I have chronic obstructive pulmonary disease (COPD) or emphysema. Can environmental odors make my COPD or emphysema worse?
In many instances, yes, odors can make COPD or emphysema worse. Using your inhalers, staying indoors, or leaving the area for a few hours can help.
I am pregnant. Can environmental odors affect the baby I am carrying?
In general, it depends on the amount of substance (concentration) in the air that you are breathing, how often (frequency) you are breathing that air, how much time (duration) you spend breathing that air, and your stage in the pregnancy (the baby is more vulnerable during the first trimester).
Staying indoors during bad odor days or leaving the area for a few hours can help.
Are children more sensitive to the effects of environmental odors?
They may be. Young children have a faster breathing rate than adults, so they breathe in more of the odors.
Younger children also crawl and creep closer to the ground. Some odors are heavier than air and stay closer to the ground. This can contribute to higher exposure of young children.
Are elderly people more sensitive to the effects of environmental odors?
They may be. The sense of smell decreases with age. Sometimes elderly people may not be able to smell environmental odors so they continue to stay in an affected area. Symptoms they may have will depend on their health status, amount of substance (concentration) in the air that they are breathing, how often (frequency) they are breathing that air, and how much time (duration) they spend breathing that air.
I walk/jog for exercise in my neighborhood. Am I at risk for developing environmental odor symptoms?
In general, it depends on amount of substance (concentration) in the air that you are breathing, how often (frequency) you are breathing that air, and how much time (duration) you spend breathing that air. But, if you are sensitive to environmental odors, any level of odor may make you feel sick. Jogging and other forms of exercise increase your breathing rate, making you breathe in more of the odor. Exercising indoors during bad odor days can help.
- Page last reviewed: August 25, 2015
- Page last updated: April 29, 2014
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