Understand indoor air in homes, schools, and offices
Most of us spend much of our time indoors. The air that we breathe in our homes, in schools, and in offices can put us at risk for health problems. Some pollutants can be chemicals, gases, and living organisms like mold and pests. Several sources of air pollution are in homes, schools, and offices. Some pollutants cause health problems such as sore eyes, burning in the nose and throat, headaches, or fatigue. Other pollutants cause or worsen allergies, respiratory illnesses (such as asthma), heart disease, cancer, and other serious long-term conditions. Sometimes individual pollutants at high concentrations, such as carbon monoxide, cause death.
Learn about pollutants
Understanding and controlling some of the common
pollutants found in homes, schools, and offices may help
improve your indoor air and reduce your family’s risk of
health concerns related to indoor air quality (IAQ).
Radon is a radioactive gas that is formed in the soil. It can
enter indoors through cracks and openings in floors and
walls that are in contact with the ground.
Radon is the leading cause of lung cancer among
nonsmokers, and the second leading cause of lung cancer
Secondhand smoke comes from burning tobacco products.
It can cause cancer and serious respiratory illnesses.
Children are especially vulnerable to secondhand smoke.
It can cause or worsen asthma symptoms and is linked to
increased risks of ear infections and Sudden Infant Death
Combustion Pollutants are gases or particles that come
from burning materials. In homes, the major source of
combustion pollutants are improperly vented or unvented
fuel-burning appliances such as space heaters, woodstoves,
gas stoves, water heaters, dryers, and fireplaces. The types
and amounts of pollutants produced depends on the type of
appliance, how well the appliance is installed, maintained,
and vented, and the kind of fuel it uses. Common
combustion pollutants include:
Carbon monoxide (CO) which is a colorless, odorless
gas that interferes with the delivery of oxygen
throughout the body. Carbon monoxide causes
headaches, dizziness, weakness, nausea, and even death.
Nitrogen dioxide (NO2) which is a colorless, odorless
gas that causes eye, nose and throat irritation, shortness
of breath, and an increased risk of respiratory infection.
Volatile organic compounds (VOCs) are chemicals found
in paints and lacquers, paint strippers, cleaning supplies,
varnishes and waxes, pesticides, building materials
and furnishings, office equipment, moth repellents, air
fresheners, and dry-cleaned
clothing. VOCs evaporate into
the air when these products are
used or sometimes even when
they are stored.
Volatile organic compounds
irritate the eyes, nose and
throat, and cause headaches,
nausea, and damage to the
liver, kidneys, and central
nervous system. Some of them can cause cancer.
Asthma triggers are commonly found in homes, schools,
and offices and include mold, dust mites, secondhand
smoke, and pet dander. A home may have mold growing on
a shower curtain, dust mites in pillows, blankets or stuffed
animals, secondhand smoke in the air, and cat and dog
hairs on the carpet or floors. Other common asthma triggers
include some foods and pollutants in the air.
Asthma triggers cause symptoms including coughing,
chest tightness, wheezing, and breathing problems. An
asthma attack occurs when symptoms keep getting worse
or are suddenly very severe. Asthma attacks can be life
threatening. However, asthma is controllable with the
right medicines and by reducing asthma triggers.
Molds are living things that produce spores. Molds produce
spores that float in the air, land on damp surfaces, and grow.
Inhaling or touching molds can cause hay fever-type
symptoms such as sneezing, runny nose, red eyes, and
skin rashes. Molds can also trigger asthma attacks.
Improving your air
Take steps to help improve your air quality and reduce your
IAQ-related health risks at little or no cost by:
Controlling the sources of pollution: Usually the
most effective way to improve indoor air is to eliminate
individual sources or reduce their emissions.
Ventilating: Increasing the amount of fresh air brought
indoors helps reduce pollutants inside. When weather
permits, open windows and doors, or run an air conditioner
with the vent control open. Bathroom and kitchen fans that
exhaust to the outdoors also increase ventilation and help
Always ventilate and follow manufacturers’ instructions
when you use products or appliances that may release
pollutants into the indoor air.
Changing filters regularly: Central heaters and air
conditioners have filters to trap dust and other pollutants in
the air. Make sure to change or clean the filters regularly,
following the instructions on the package.
Adjusting humidity: The humidity inside can affect the
concentrations of some indoor air pollutants. For example,
high humidity keeps the air moist and increases the
likelihood of mold.
Keep indoor humidity between 30 and 50 percent. Use a
moisture or humidity gauge, available at most hardware
stores, to see if the humidity in your home is at a good
level. To increase humidity, use a vaporizer or humidifier.
To decrease humidity, open the windows if it is not humid
outdoors. If it is warm, turn on the air conditioner or adjust
the humidity setting on the humidifier.
Important tips that will help control indoor
• Test for radon and fix if there is a problem.
• Reduce asthma triggers such as mold and dust mites.
• Do not let people smoke indoors.
• Keep all areas clean and dry. Clean up any mold and get rid of excess water or moisture.
• Always ventilate when using products that can release pollutants into the air; if products must be stored following use, make sure to close tightly.
• Inspect fuel-burning appliances regularly for leaks,and make repairs when necessary.
• Consider installing a carbon monoxide alarm.
Remodeling old homes and building new homes
While remodeling or improving the energy efficiency of
your home, steps should be taken to minimize pollution
from sources inside the home, either from new materials or
from disturbing materials already in the home. In addition,
residents should be alert to signs of inadequate ventilation,
such as stuffy air, moisture condensation on cold surfaces,
or mold and mildew growth.
When building new homes, homebuyers today are
increasingly concerned about the IAQ of their homes.
Pollutants like mold, radon, carbon monoxide, and toxic
chemicals have received greater attention than ever as
poor IAQ has been linked to a host of health problems.
To address these concerns, builders can employ a variety
of construction practices and technologies to decrease the
risk of poor IAQ in their new homes using the criteria from
EPA’s Indoor airPLUS as a guide.
To help ensure that you will have good IAQ in your new or
- Ask about including radon-reducing features.
- Provide proper drainage and seal foundations in new construction.
- Consider installing a mechanical ventilation system.
Mechanical ventilation systems introduce fresh air using
ducts and fans, instead of relying on holes or cracks in
the walls and windows.
- When installing new appliances (like furnaces) make
sure they are installed properly with a good vent or flue.
With nearly 56 million people, or 20 percent of the U.S. population, spending their days inside elementary and secondary schools, IAQ problems can be a significant concern. All types of schools—whether new or old, big or small, elementary or high school—can experience IAQ problems. School districts are increasingly experiencing budget shortfalls and many are in poor condition, leading to a host of IAQ problems.
- EPA’s voluntary Indoor Air Quality Tools for Schools Program provides districtbased
guidance to schools about best practices, industry guidelines, and practical
management actions to help school personnel identify, solve, and prevent IAQ
- Children may be more sensitive to pollution, and children with asthma are
especially sensitive. Asthma is responsible for millions of missed school days each
year. Parents’ and caregivers’ involvement helps daycare facilities become aware
of asthma triggers and the need to reduce them.
Many office buildings have poor IAQ because of pollution sources
and poorly designed, maintained, or operated ventilation systems.
- Office workers help to improve the indoor air in their buildings
by paying attention to environmental conditions including
ventilation, temperature, and the presence of odors. Report any
problems to facility managers immediately.
- To improve IAQ, be careful not to block air vents or grilles,
keep your space clean and dry, and do not bring in products that
may pollute the indoor air.