CenterPoint Energy

Natural Gas > Business

Indoor Air Quality
Is your building sick? We can help you find the cure.

New and existing buildings can develop Indoor Air Quality (IAQ) problems. According to a World Health Organization Committee study, up to 30 percent of new and remodeled buildings worldwide may be suffering from "sick building syndrome."

Good indoor air quality contributes to a healthy and productive environment and creates a sense of comfort and well-being. Bad indoor air quality can have many adverse effects including long-term health problems. Proper maintenance of indoor air is more than a "quality" issue; it includes the safety and good management of your investment in your staff and facilities.

Does your facility suffer from Sick Building Syndrome?

Take our IAQ quiz to find out.

Q: Do occupants in your building experience:

  • headache, fatigue and/or shortness of breath?
  • sinus congestion, coughing and sneezing?
  • eye, nose, throat and/or skin irritation?
  • dizziness and nausea?

Q: Are any of these symptoms localized within a certain area or widespread throughout the building?

Q: Do these symptoms disappear when the occupant(s) leave the building?

Q: Do occupants often comment that "there is a funny smell in here?"

If you answered "yes" to any one of these questions, your facility could be suffering from Sick Building Syndrome (SBS). SBS is used to describe cases where building occupants experience acute health and comfort effects that are linked to time spent in the building and not to an illness. Many different indoor air quality symptoms have been associated with SBS, including respiratory complaints, fatigue and irritation. Complaints may be localized in a specific area or widespread throughout the building.

Factors influencing indoor air quality

According to Environmental Protection Agency (EPA) studies, human exposure to indoor air pollutants may be two to five times -- occasionally more than 100 times -- higher than outdoor pollution levels. Indoor air pollution, or Sick Building Syndrome, is among the EPA's top four environmental risks to public health.

During the past 40 or 50 years, exposure to indoor air pollution has increased due to a variety of factors including:

  • construction of more tightly sealed buildings
  • use of synthetic building materials and furnishings
  • use of chemically formulated cleaning products, personal care products, perfumes, air fresheners, and pesticides
  • HVAC systems and equipment
  • indoor humidity levels which are too high or too low

When the heating, ventilation and air-conditioning system is properly designed, installed and in good working condition, it:

  • controls temperature and humidity
  • distributes adequate amounts of outdoor air to meet ventilation needs of building occupants
  • isolates and removes odors, dust, allergens and pollutants through pressure control, filtration and exhaust fans.

Examples of indoor air pollutants

Indoor air contaminants can originate within the building or be drawn in from the outside. If the source of contamination is not located and controlled, indoor air quality problems can arise. Following are some examples of indoor air pollutants.

External sources


  • pollen, dust and fungal spores
  • industrial pollutants (e.g., smoke, fumes)
  • vehicle exhaust

Emission from other sources nearby

  • exhaust from traffic, loading docks and parking garages and lots
  • dumpster odors
  • building exhaust that is being drawn back in

Soil gas

  • radon
  • underground fuel tank leakage
  • contaminants from previous site usage (e.g., landfills)

Standing water (environs for microbial growth)

  • rooftops
  • crawl space
  • below ground floors or storage areas

Equipment, internal or external

  • HVAC system
  • dirt and dust in ductwork
  • microbiological growth in drain pans, humidifiers, ductwork and coils
  • improper use of biocides, sealants and/or cleaning compounds
  • improper venting of combustion products
  • refrigerant leakage

Non-HVAC systems

  • emissions from office equipment, e.g., volatile organic compounds, ozone
  • supplies, e.g., solvents, toner, ammonia
  • emissions from shops, labs, cleaning processes, etc.
  • elevator motors or other mechanical systems

Moldy Ductwork






Moisture problems have caused mold to grow on concrete around ductwork in this commercial building. Photo courtesy of Advanced Certified Thermography.

Other internal sources

Human activities

  • perfume, cologne, cosmetics, smoking, body odor
  • cleaning materials, supplies and/or procedures
  • fumes from paint, adhesives, deodorizers and other products
  • excessive CO₂ from gas exhaled as well as a byproduct of combustion and photosynthesis

Building components and furnishings

  • carpet, curtains and upholstery that can produce as well as collect dust, fibers and odors
  • open shelving
  • microbiological growth in soiled or water-damaged furnishings and building materials
  • food preparation areas
  • poorly designed or clogged drains (standing water) and dry traps that allow sewer gas to escape

This list is only a sampling of the sources of indoor air pollution. Your CenterPoint Energy professional can help identify many others.


Many experts agree that moisture control is the single most important factor in achieving healthier indoor air. If your building has a humidity problem, then, for example, a desiccant dehumidification system integrated into the HVAC system could improve occupant comfort and increase energy savings. A natural gas desiccant dehumidification system acts as a prefilter. Drier air reduces airborne bacteria and thus creates a healthier environment for everyone.

If your building has a humidity control problem, it could have other problems as well. Excessive humidity can also weaken your building's construction; moisture or condensation can deteriorate walls, destroy insulation, dissolve concrete, bring down ceilings and roofs, and rot or warp wooden moldings, frames and floors. Contact us to discuss solutions to your indoor air quality concerns. You can also check out the American Lung Association and the Texas Department of State Health Services for more information.