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Indoor Environmental Quality


To create and maintain a comfortable and healthy indoor environment in the home, it is important to look at and evaluate the home as a system, in which each component of the building must work together — the building shell, mechanical systems, furnishings, construction materials, and inhabitants and their activities. Changes to one component in the system may affect the performance of other components.

The building shell consists of the roof, walls and foundation. The shell isolates and insulates the indoors from the outdoors. It keeps outdoor contaminants from entering the building, such as dusts, liquid water, humidity, air pollution and pests. Insulation in the building shell helps to protect the interior from temperature extremes.

Mechanical systems include:

  • the electrical system/gas system that provides energy to the building;
  • the plumbing system and waste water systems, which provide clean water and remove waste water;
  • and the Heating Ventilation and Air-Conditioning (HVAC) system, which provides outdoor air, modifies indoor temperature and humidity, and removes pollutants from point sources such as fuel-burning appliances, bathrooms, kitchens and clothes dryers.

Furnishings such as furniture, wall and floor coverings can give off contaminants or become reservoirs for pests. Building materials, appliances and equipment, showers and washers/dryers can be sources of contaminants. We, along with our pets, can also be sources of contaminants. The things we do (hobbies, cooking) and the materials we use, such as candles, cleaning products, pesticides and paints, also affect the indoor environment.

People often worry about how specific indoor air pollutants can affect their health. Instead, most health problems associated with indoor environments can be prevented by understanding how building systems work together and by using sound environmental management principles. To help people achieve healthy indoor environments, the National Center for Healthy Housing External link has developed a list of seven simple "Principles for Healthy Homes": dry, clean, ventilated, well maintained, pest-free, contaminant-free, and safe.

1. Dry

Prevent leaks from the roof, windows, or walls. Quickly repair plumbing leaks. There should be no condensation on windows. Make sure that grading and drainage keeps surface water from contacting the foundation or entering the crawlspace/basement. Use exhaust ventilation for bathrooms, kitchens and clothes dryers to remove water vapor and the contaminants they generate. Keep chimneys and flues in safe working order. Do not over-water plants.

Keep the relative humidity in the building below 60 percent at all times. This keeps most people in the building comfortable and will prevent condensation. Learn more about the roles of moisture and heating, air conditioning and ventilation (HVAC) systems in indoor environmental quality.

2. Clean

Keep surfaces, equipment and appliances free of dust, dirt, debris, soils, oily residues and visible mold growth. Reduce clutter. Think of cleaning as an environmental management activity of removing unwanted contaminants from the environment. Clean smart by using tools, equipment and supplies that collect, extract and remove soils, dirt, dust, debris and bio-films from the environment using the least harmful materials and that leave minimal residues.

3. Ventilated

Bathrooms, clothes dryers, kitchens and fuel-burning appliances generate moisture and pollutants. They should have exhaust systems capable of removing moisture and other pollutants from the building and should be vented to the outdoors.

Make sure that enough clean and dry outdoor air circulates through the building by natural or mechanical ventilation to dilute pollutants generated by people's activities and to replace air exhausted by bathroom and kitchen ventilation, clothes dryers, and from fuel-burning appliances such as heaters, hot water heaters, fire places and gas logs.

Keep the temperature in the building higher than 65° F in the winter and below 80° F in the summer.

Air conditioners and heating systems should be inspected and serviced twice a year to get the best performance and to keep pollutants out of the building. Change air conditioner filters at least every three months. Make sure that air conditioner condensate pan drains flow freely.

4. Well Maintained

The roof, exterior walls, and foundation should be maintained and sealed to prevent unintended air flow, outdoor pollutants, and pests from entering the building. Repair flaking or peeling paint as well as decay or damage to exterior and interior walls. Keep fuel-burning equipment such furnaces, hot water heaters, fire places, wood stoves, gas stoves and heaters properly maintained and vented to the outside. Make sure electrical, plumbing, sanitary, heating, ventilation and air-conditioning systems are in good working order.

5. Pest-Free

Use an integrated pest management approach to keep pests out of the building. Seal or repair cracks in walls, and foundations. Keep the building clean, dry and uncluttered to deny pests food, water and a place to hide. If needed, apply pesticides carefully to target the pest, while limiting people's exposure to pesticide residues and minimizing environmental consequences.

6. Contaminant-Free

Limit the pollutants generated inside of the building. Prohibit indoor tobacco smoking. Limit the use of air fresheners, deodorizers, scented candles, and scented cleaning products. Do not use ozone-generating air purifiers. Indoor pets should be bathed and brushed regularly to reduce dander.

Never use unvented fuel-burning heaters or gas logs indoors. All fuel-burning appliances can emit unhealthy combustion products such as carbon monoxide, oxides of nitrogen, fine particles and water vapor.

NEVER USE a charcoal or gas grill indoors for cooking or heating. NEVER USE a gas oven to heat the home. Never use propane or fuel camping equipment indoors. NEVER USE a gasoline-powered generator or any gasoline-powered equipment indoors. These items MUST be used outdoors, in a well-ventilated area away from the home's windows, doors and air-intakes, as they produce deadly carbon monoxide.

DO NOT let automobile engines idle or any gasoline-powered equipment run while in an attached garage.

Select building materials, furnishings and supplies that do not emit volatile organic compounds (VOCs) or other toxic materials.

Hobbies utilizing paints, glues or other chemicals should be conducted outdoors.

Use doormats at entryways or remove shoes before entering the home to reduce track-in of soil particles by people and pets. Soil particles often contain toxic components such as lead and pesticide residues; they can become re-suspended in the indoor air and inhaled, or be ingested by small children who play on the floor.

Use gels or baits instead of broad spraying or fogging. Learn more about pesticides and your health.

7. Safe

Improve home safety: Use safety gates, latches, guard rails and grab bars to prevent falls. Keep medicines stored away from children. Hazardous chemicals such as cleaning products, pesticides, batteries, corrosive materials and irritants should be stored away from food, inaccessible to children, and in properly labeled containers. Make sure that flammable liquids such as gasoline or propane are stored in approved containers outdoors. Every home should have properly located and working smoke detectors and carbon monoxide alarms.

Other important safety measures: Uprights and railings on guard rails and cribs should be spaced close enough to each other to prevent a child from falling through, but far enough apart to prevent choking. Keep cords from window blinds and extension cords out of children's reach to prevent choking. All firearms should be stored unloaded in a locked location; store ammunition separately. Make sure swimming pools have fences with lockable gates to prevent unauthorized entry, and that children playing in or near the pool are under direct supervision of a responsible adult.

By following the seven principles listed above, building components work in harmony and most problems in the indoor environment can be prevented.

Renting and Leasing

Both landlords and tenants must work together to create homes that promote health and well-being. Residential leases and rental agreements are contracts between landlords and tenants that define each party’s obligations. In addition, some jurisdictions have minimum housing codes or property maintenance codes to define roles and responsibilities.

North Carolina General Statutes also define responsibilities in these agreements. Landlords are required to provide a dwelling fit for habitation, keep all the facilities provided under the agreement in good safe working condition, provide a working smoke detector, provide a carbon monoxide alarm if the dwelling has a fuel burning appliance, and repair any of 12 specified conditions in a reasonable time when notified by the tenant (in writing).

Tenants are generally responsible for keeping the dwelling as clean as conditions permit, disposing all wastes (garbage, trash and ashes), preventing unsanitary conditions from developing, and preventing intentional damage to the property beyond normal wear and tear.

Landlords cannot legally evict tenants who complain about bad conditions such as requesting repairs for legitimate safety and health reasons, complaining to a government agency about violations of health or safety laws or any other law, joining a tenant’s organization, or trying to get your rights under the lease.

Landlord and tenant disputes may ultimately be resolved in small claims court.

For Additional Information