Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, especially concerning the health and comfort of building occupants. Understanding and controlling common pollutants indoors can help reduce your risk of indoor air quality-related health concerns. Relevant factors include air temperature, relative humidity levels, and airborne and surface contaminants. A building's indoor air quality is typically considered acceptable if occupants are not exposed to harmful contaminant concentrations and a large majority of the occupants are satisfied with IAQ conditions.
Occupants' perceptions of IAQ for a building or a space within a building can vary because of individual variations in temperature/humidity level preferences and sensitivities to chemical and biological contaminants. Perceptions can also be affected by issues not associated with indoor air conditions, such as unrelated health problems, and psychosocial factors, such as work-related or personal stress.
A building's IAQ is a product of several factors, including ventilation system operation, contaminant sources, and occupant activities.
Most classrooms and offices in MCPS facilities are served by mechanical heating, ventilating, and air-conditioning (HVAC) systems. HVAC systems for classrooms and offices are designed to control indoor temperatures by supplying heated or cooled air. These systems are also designed to dilute and remove airborne contaminants by providing a continuous supply of filtered outdoor air.
IAQ can be affected by the presence of contaminants, substances that can adversely affect occupant health and comfort. Common indoor pollutants include dust, fungal particles, pollen, bacteria and viruses, radon, emissions from furnishings and building materials, office equipment emissions, vehicle exhaust, emissions from cleaning and maintenance products, sewer gas, mites, animal-derived substances (insect and rodent feces and carcasses), and emissions from educational chemical products (paints, adhesives, photographic chemicals, ceramic materials).
Indoor and outdoor sources can generate indoor contaminants. Common indoor sources include cleaning products, maintenance and repair products, building materials, furnishings, dirty ventilation equipment, faulty plumbing equipment, office equipment, art and science products, pesticides, animals, biological contamination, and air fresheners. Occupants can also act as indoor contaminant sources by introducing communicable diseases, irritants (such as personal fragrances), and allergens (animal dander, pollen, mold spores). Common outdoor sources include idling automobiles, plant life, decomposing organic matter, garbage dumpsters, soil and rocks, water, and building exhausts near outdoor air intakes for HVAC equipment.
Occupant activities can impact IAQ by affecting contaminant generation and HVAC system performance. Indoor air contaminants can be generated by various occupant activities, such as maintenance and repair work, construction operations, painting, housekeeping, art and science activities, and office work (copying, printing). HVAC system performance at MCPS facilities is primarily determined by how occupants maintain and operate ventilation equipment. Occupants can ensure adequate performance through routine preventive maintenance (cleaning and inspecting mechanical components, replacing dirty air filters) and proper operation (leaving ventilation units on, guaranteeing that grilles/diffusers are not obstructed, leaving windows and doors closed, maintaining appropriate thermostat settings, and ensuring that thermostats are adequately exposed to room air).
IAQ has received increasing attention in the last 10–15 years as U.S. Environmental Protection Agency (EPA) air pollution studies have determined that indoor contaminant concentrations can be 2-5, and sometimes more than 100 times, higher than outdoor concentrations. Because children are believed to be more susceptible to air contaminants, IAQ is especially important for school buildings. The consequences of poor IAQ in schools, according to EPA, include:
Occupants play a significant role in ensuring acceptable IAQ in their buildings. Listed below are several action items MCPS personnel can complete to improve conditions in their buildings. MCPS personnel can also evaluate their buildings using detailed checklists provided by EPA. More information can be found on the IAQ Tips for Teachers page.
Additional IAQ-related information can be found at the websites listed on our main IAQ page. More information about MCPS's IAQ programs can be obtained by contacting Brian Mullikin by phone (240-740-2324) or email (Brian_A_Mullikin@mcpsmd.org).