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NC Department of Health and Human Services
NC Division of Public Health
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Occupational & Environmental Epidemiology

Indoor Environmental Quality

In any building, the four basic factors that affect indoor environmental quality, or IEQ, are indoor pollutant sources; heating, ventilation, and air-conditioning (HVAC) systems; pollutant pathways; and occupants and their activities or practices. Construction of more tightly sealed buildings, reduced ventilation rates to save energy; the use of synthetic building materials and furnishings; increased use of chemical products such as pesticides and housekeeping supplies, and personal care products, all have an impact on the building IEQ.

Indoor environmental quality can affect people's health and can have economic and legal implications. For example:

  • Poor IEQ increases asthma risk. There is ample and clear evidence that environmental exposures can make asthma worse, and mounting evidence that many of those same exposures may play a role in causing the disease. Numerous epidemiological studies have shown that, when asthmatics are exposed to building contaminants like dust mites, cockroach and mold antigens, combustion gases and tobacco smoke, those individuals have more frequent and more serious asthma attacks. Minimizing these exposures in the indoor environment can have a profound effect on improving the respiratory health of asthma patients. See the North Carolina Asthma Program web site, for more information.
  • Pollutants can cause or contribute to other short- and long-term health problems, including respiratory tract infections, allergic reactions, headaches, congestion, eye and skin irritations, coughing, sneezing, fatigue, dizziness and nausea.
  • Indoor pollutants can cause discomfort and reduce attendance and productivity. Recent data suggest that poor IEQ can reduce a person's ability to perform specific mental tasks requiring concentration, calculation or memory.
  • Indoor pollutants hasten building deterioration. For example, uncontrolled moisture can result in mold growth that leads to the structural decay of building components.
  • Poor indoor environmental quality strains relationships among employees, family members, parents, teachers, students and school administrators.
  • Indoor environmental quality problems can result in liability issues or lawsuits.

Indoor environmental contaminants can include:

How N.C. Public Health Can Help

Industrial hygienists, physicians and toxicologists with Occupational and Environmental Epidemiology in the North Carolina Department of Health and Human Services serve as consultants to school systems, local health departments, home owners, renters, employees, business owners, physicians, and other governmental agencies. They:

  • provide guidance and literature to the general public and others on various IEQ topics.
  • provide training and support on IEQ-related issues to local health departments and other organizations.
  • may conduct on-site IEQ evaluations of buildings such as schools, governmental offices, and selected other buildings, as requested by physicians, local health departments and other governmental agencies.