Continued from prior page include plants, animals, minerals, combus-tion and aerosols. Each comes in different sizes. Non-biological particles are Total Suspended Particles (TSP) or Respirable Suspended Particles (RSP). TSP are all sizes. RSP measure no more than 10 microns in diameter. These present the greatest health concern because they can be inhaled deep into the lungs. Most RSP are produced by cigarette smoke and using combustion appliances indoors. Cancer is the most serious health hazard associated with small particles. Others include impaired lung function and allergic responses or asthma. When measured for short periods of time indoor particle concentrations are in the 10-1,000 µg/m 3 range. Based on the National Ambient Air Quality Standards concentrations >100 µg/m 3 are considered unsanitary. Biological aerosols also consist of parti-cles originating in living plants or creatures. Plant particles include pollens, spores, molds and plant parts. Most enter the built environment through doors, windows and air handling systems. Animals and humans also produce minute amounts of biological aerosols that remain in the environment, including bacte-ria, viruses, hair, insect parts and skin cells. Ambient soils are common indoor sources of particulate matter that are organic, humic or mineral. Each has different particle construction and life support properties. Mineral dusts result from weathering or breaking down inorganic matter, such as sand, silt, clay, talc, carbons and asbestos. Other well-known dusts come from heavy metals, like lead, and man-made mineral fibers, such as fiberglass insulation. They are blown or tracked indoors or produced inside. Deemed the largest group of indoor dusts, some are carcinogenic. As a class, however, they are most dam-aging in soiling materials. Burning produces combustion dusts called products of incomplete combustion or PICs. These PICs come from tobacco products, cooking, heating appliances and outside industrial sources. Most are small enough to be inhaled into the lungs causing serious health damage. PICs are a major source of indoor pollution. Any matter left behind poses health haz-ards and damages materials. Many of these also are carcinogenic. Some are oily and sticky and adhere to surfaces. Proper ventilation and cleaning manage these products when emitted into the indoor environment. Gases, particles and organics are prod-ucts of combustion. Principal combustion gases are nitrogen and sulfur dioxide and carbon monoxide. Combustion particles form when burned solids do not enter the gas phase. Common combustion organics are formaldehyde and polynuclear aromatic hydrocarbons (PAH). Indoor sources for these contaminants include improperly ventilated combustion appliances, such as gas, cooking and wood burning stoves, water heaters, dryers and gas or kerosene space heaters. Second-hand cigarette smoke also is a contamination source, containing over 4,500 compounds or products of incom-plete combustion. Many PAHs that may cause cancer, car-diovascular problems and irritate mucous membranes are present indoors. Soot also has been associated with cancer. These black substances are by-products of incomplete combustion materials con-taining carbons. They often possess highly toxic polyclin-ic aromatic hydrocarbons, resins and incompletely carbonized fuel fragments. Consequently, special care is required to prevent inhaling, ingesting or making der-mal contact. Most soot contains inorganic matter, such as oxides, salts, metals, absorbed liquids, gases, sulfurs and nitrogen compounds. Chimney sweeps, heating unit service staff, firefighters and fire damage restora-tion staff are most susceptible to occupa-tional soot exposure. The general public also is potentially exposed because soot is a widespread envi-ronmental contaminant. Cleaning is essential in removing these potentially toxic substances. Among the non-combustion particles in the indoor air that cause concern are man-made cleaning dusts, health and beauty sprays and cooking aerosols. Concentrations vary depending on the activity’s duration and intensity. Surprisingly, humidifiers, generally con-sidered a health aid, also generate undesir-able particles. Tap water may produce mineral parti-cles, which if not removed through clean-ing can produce biological pollutants that are sprayed into the air. Many heavy metals are carcinogens. Metals and metal compounds of most concern are those found in house dusts: arsenic (salts, arsenates, arsenites), berylli-um, cadmium (oxide, bromide, chloride), chromium (hexavalent), nickel (carbonyl, subsulfide) and selenium (sulfide). Indoor dusts are tracked in by surface soil and deposits of airborne particles orig-inating outside. They also originate from indoor mecha-nisms and activities, such as smoking, nor-mal wear and tear and household products containing heavy metals. Tobacco smoke is a primary source of cadmium. When metal concentrations, such as lead, are measured indoors there are alarm-ingly high levels of heavy metal contami-nation, mainly from outside sources. It is safe to expect that many indoor metal concentrations relate to outdoor pollutants. Studies of metal smelting identify sur-face soils as the greatest contributors to specific indoor particles. Sometimes the average metal concen-tration in house dusts is similar to that in the soil. A common misperception about particle sizes — known as the small particle para-dox — needs clarification to effectively manage indoor allergens. There is a misconception that only indoor particles <2.5-10 µm are a concern. Actually all size particles are important to varying degrees. Generally, the size of allergen particles is CM larger than this small range. 30 CM/Cleaning & Maintenance Management ® • March 2009
CMM – Archives Mar 2009: 30
