Common Causes of Indoor Air Quality Problems

Indoor air quality can be affected by many conditions inside and around a home. Airborne particles, chemical compounds, moisture, combustion byproducts, odors, and inadequate ventilation can all contribute to indoor environmental concerns.

Some sources are easy to identify, such as smoke or a strong chemical odor. Others may not be visible or noticeable without professional testing. A home can appear clean and well maintained while still having elevated levels of certain airborne contaminants or environmental conditions that affect the quality of the indoor environment.

Understanding the common causes of indoor air quality problems can help homeowners recognize when further evaluation may be appropriate.

What Causes Poor Indoor Air Quality?

Indoor air quality problems can come from many different sources. Some originate inside the home, while others enter from outdoors. Ventilation, humidity, building materials, household products, HVAC systems, and fuel-burning equipment can all influence the air inside a home.

Poor Ventilation and Air Circulation

Ventilation plays an important role in maintaining indoor air quality. Homes with limited fresh-air exchange may allow certain pollutants, odors, moisture, and airborne particles to accumulate instead of being diluted or removed. Air movement can also affect how contaminants are distributed throughout a home. HVAC systems, fans, open windows, and other sources of air movement can move particles and other substances between different areas.

Carbon dioxide testing can provide useful information about ventilation conditions because indoor CO₂ concentrations can increase when occupied spaces have limited fresh-air exchange.

Excess Moisture and Humidity

Temperature and humidity can have a significant effect on the indoor environment. Elevated relative humidity can contribute to condensation and moisture problems and can create conditions favorable for mold growth. Moisture may come from plumbing leaks, roof leaks, condensation, damp basements or crawlspaces, or inadequate ventilation.

Humidity that is consistently too low can also affect occupant comfort.

Measuring temperature and relative humidity can therefore provide important context when evaluating other indoor air quality conditions.

HVAC Systems and Filtration

Heating and cooling systems can influence the movement of airborne particles throughout a home. HVAC equipment, ductwork, filters, and humidification systems may all affect how dust, particulates, allergens, and other contaminants circulate.

Construction activity, accumulated dust, outdoor pollution, and other sources can also introduce particles into an HVAC system or the surrounding indoor environment.

Professional particulate testing can help characterize the concentration and size of airborne particles present in the home.

Combustion Appliances

Fuel-burning equipment can be an important consideration when evaluating indoor air quality. Furnaces, boilers, fireplaces, water heaters, generators, and other combustion appliances can produce combustion-related pollutants when equipment is malfunctioning, improperly vented, or inadequately maintained.

Carbon monoxide is particularly important because it is a colorless and odorless gas that can present a serious safety concern at elevated concentrations.

Indoor Air Quality testing does not replace properly installed and maintained carbon monoxide alarms. Homeowners should continue to use appropriate safety devices throughout the home.

Volatile Organic Compounds

Volatile organic compounds, commonly called VOCs, are gases released by many products and materials found in homes.

Potential sources include:

• Paints and coatings
• Flooring
• Furniture
• Cabinetry
• Adhesives
• Cleaning products
• Air fresheners and fragrances
• Building materials
• Newly installed materials

VOCs may be particularly relevant following renovations, when furnishing a new space, or when investigating unexplained chemical odors.

TVOC testing can measure the overall concentration of volatile organic compounds in the indoor environment. More detailed laboratory sampling can also help identify individual compounds present in an air sample.

Building Materials and Furnishings

Materials used to construct, renovate, or furnish a home can influence indoor air quality. Flooring, carpeting, upholstery, pressed-wood products, cabinetry, insulation, adhesives, and other building materials may release airborne particles or chemical compounds.

Newly renovated or newly furnished spaces may therefore warrant additional attention when homeowners notice unusual odors or other indoor environmental concerns.

Household Products and Activities

Everyday household activities can introduce or increase airborne contaminants. Cleaning products, disinfectants, pesticides, personal-care products, cooking, hobbies, and renovation work can all affect the air inside a home.

These sources can vary considerably from one household to another, which is one reason an indoor air quality assessment may need to consider the specific conditions and activities within the property.

Outdoor Pollutants

Indoor air quality is also affected by what enters the home from outside.

Pollen, smoke, fine particulate matter, pesticides, vehicle emissions, and other outdoor contaminants can enter through doors, windows, ventilation systems, and normal air leakage.

Radon is another example of an environmental contaminant that can enter a home from the soil beneath and around the structure. Radon requires its own testing approach and should not be assumed to be adequately evaluated through general IAQ measurements.

Can Indoor Air Quality Problems Exist Without an Odor?

Yes. Not every indoor air quality concern produces a noticeable smell.

Some airborne contaminants and environmental conditions cannot be reliably identified through sight or smell alone. Formaldehyde, for example, can be present without an obvious odor, while carbon monoxide is colorless and odorless. Other conditions, such as elevated particulate concentrations or ventilation concerns, may also require measurement to evaluate objectively.

For this reason, unusual odors can be a reason to investigate indoor air quality, but the absence of an odor does not necessarily mean that the indoor environment is free of contaminants.

How Can Homeowners Tell if Indoor Air Quality Should Be Evaluated?

Certain conditions may warrant a closer look at the indoor environment, including:

• Persistent or unexplained odors
• Excessive dust
• Concerns about humidity or condensation
• Recent renovations
• New flooring, cabinetry, furniture, or other materials
• Water damage or moisture problems
• Concerns about mold
• Suspected combustion issues
• Poor ventilation
• Unexplained changes in indoor air conditions

Testing can provide objective information about conditions that may not be apparent through visual observation alone.

How 5D Home Inspections Evaluates Indoor Air Quality

5D Home Inspections provides professional Indoor Air Quality testing designed to evaluate multiple components of the indoor environment. Depending on the concerns being investigated, testing may include measurements of temperature, relative humidity, particulate matter, VOCs, carbon dioxide, carbon monoxide, hydrogen sulfide, ozone, formaldehyde, chlorine, ammonia, and oxygen concentration.

Additional sampling and laboratory analysis may be used when more detailed information is needed.

Because different contaminants require different testing methods, a comprehensive assessment considers the results together rather than relying on a single measurement.

Understanding What’s in Your Indoor Air

Indoor air quality can be influenced by ventilation, moisture, HVAC systems, combustion appliances, household products, building materials, outdoor pollutants, and many other factors. Identifying the source of an indoor environmental concern is not always straightforward. Conditions can vary from room to room and can change over time.

Professional Indoor Air Quality testing can provide measurable information about the conditions inside a home and help homeowners better understand what may be affecting their indoor environment.

5D Home Inspections combines professional instrumentation, targeted sampling, laboratory analysis, and observations of the home to provide a more complete assessment of indoor air quality.

If you are concerned about unexplained odors, excessive dust, humidity, VOCs, airborne particles, ventilation, or other indoor environmental conditions, professional testing can provide objective information about what is happening inside the home.