- Did You Know?
- Eliminating individual sources of pollution or reducing their emissions is usually the best way to improve indoor air quality.
Within a home or building, physical (e.g. dust), biological (e.g. mold, dander), and chemical pollutants [e.g. volatile organic compounds (VOCs) like solvents] are common sources of irritation. Personal care products, pesticides, cleaning and air deodorizing products, and building furnishings can be sources of irritants within a building. Some of these sources, especially glues, fragrances, and materials off-gassing from pressed-wood furnishings, and permanent press fabrics (e.g. curtains), may remain in a room or building when ventilation is poor.
While ventilation is important in diluting and removing typical indoor pollutants, reducing or eliminating the use of materials that cause irritation is the best indoor air practice. For example, stopping the use of air deodorizing products that mask odors from a room can prevent respiratory irritation. Irritants such as particulate matter and VOCs can have unwanted short- and long-term health effects.
Types of Irritant Sources
Particles in the air can also affect indoor air quality. PM2.5 refers to fine liquid or solid particles that are 2.5 microns in diameter or less. Because of their small size, PM2.5 can penetrate deep into the lungs and get into the bloodstream. PM2.5 can aggravate pre-existing respiratory conditions, such as asthma. Children are particularly sensitive to particulate matter, since they breathe more air per pound of body weight than adults. Indoor sources of PM2.5 can include pet dander, bacteria, mold, chemicals from cleaning products, building materials, candles, fuel burning equipment such as furnaces, upholstered goods, cooking, sweeping, and discharge from kilns and copy machines. Outdoor PM2.5 sources, such as vehicle exhaust and tobacco smoke, often enter a building and contribute to the particulates within a building.
Whether the source is indoors or outdoors, it is important to reduce indoor particulate pollutants. Some ways to reduce respirable dusts indoors include:
- Limiting the use of products such air deodorizers can reduce sources of particles in the indoor environment.
- Using localized exhaust ventilation during cooking or copying, as well as servicing, maintaining, and changing filters on heating and cooling equipment help to remove or dilute indoor PM2.5.
- Cleaning surfaces using a wet wipe, microfiber cloth, or HEPA-filtered vacuum can prevent settled particles from being recirculated.
- Using door doormats at entry points to lessen dust tracked into the home.
- Closing windows when pollen or particle levels are forecasted to be high.
Volatile Organic Compounds
Volatile organic compounds (VOCs) are gases emitted or off-gassed from items, such as cleaning products, building materials and furnishings. VOCs are commonly released indoors when cleaning products are sprayed or applied, air deodorizers are installed, personal care products (e.g. perfumes, colognes) are used, new furnishings are brought in, or walls are painted. Concentrations of many VOCs are typically higher indoors than outdoors. While ventilation can help to lower VOC levels indoors, limiting the use of these products can reduce the potential for allergies and other adverse health effects.
Indoor Air Quality and Irritant Sources in Public Buildings
During an assessment of a school building, staff from the Indoor Air Quality Program take measurements or make observations for processes or products that can contribute to respirable particles or cause off-gassing of VOCs. Indoor Air Quality Program staff measure PM2.5 levels in each area evaluated in a public building to decide if ventilation is working to remove respirable dusts. Staff also note processes or products that may contribute to PM2.5 indoors, such as metalwork, wood cutting, or clay art drying in kilns. While there are currently no government standards for indoor PM2.5 concentrations, the MDPH uses the US EPA’s National Ambient Air Quality Standard (NAAQS) of 35 µg/m3 (a 24-hour limit) to evaluate indoor PM2.5 levels. Frequently, indoor air particulate levels (including PM2.5) can be higher than those measured outdoors.
Additionally, Indoor Air Quality Program staff identify whether VOC-containing products, such as cleaners, deodorizers, and dry erase materials, are present in a classroom. Indicating the presence of these products can help school staff work towards reducing the number of irritant products within their school.