Volatile organic compounds (VOCs) and semivolatile

by:Sycda     2020-08-27

In fact, there are no places in schools where VOCs and SVOCs are not found. Outdoor sources of VOCs and SVOCs include fuels and combustion, biological organisms, and pesticides. Research has shown that concentrations of VOCs are consistently higher indoors than outdoors (Adgate et al., 2004; Wallace, 1991), and studies in homes suggest that indoor concentrations vary depending on the specific VOC (Weisel et al., 2005; Meng et al., 2005). One study also showed that building renovation contributes significantly to total VOC concentrations (Crump et al., 2005). Particulate matter (PM) includes solid particles ranging in size from ultrafine to relatively large. These particles come from outdoors (including dusts and particles from traffic, stationary sources, and microorganisms), and indoors (humans, building materials, fibers, bioaerosols, mold, pet dander) (Afshari et al., 2005). Larger PM remains suspended in air for relatively short periods of time, instead settling on floors, surfaces, and furnishings.

Smaller PM has longer suspension times-i.e., it remains airborne longer. Particulate matter has been implicated in a number of health effects, primarily respiratory and cardiac (Nel, 2005). Particulate matter can absorb VOCs, which may affect occupants' health and comfort. Larger PM tends to be related to housekeeping practices, ineffective filtration by HVAC systems, and local activity. Finer PM tends to be more independent of these factors, and a fraction of finer PM will even diffuse through structures and so be not removable by HVAC filtration. One important group of PM is the airborne allergens, including molds and fungi, dander and other body fragments, dust mites, and cockroach antigens. Because these bioaerosols can induce an immune response, they are capable of causing illness at very low exposure levels and also of causing more severe respiratory disease than PM from nonbiological sources.

The strength of the association of each of these bioaerosols with illness was summarized in Clearing the Air: Asthma and Indoor Air Exposures (IOM, 2000), and many of them were found to be more strongly related to asthmatic symptoms than were moisture and mold. Learning things is not limited to the scentific area. Instead it also has relations with some other things like speaking a language or using software, including Rosetta Stone German and Rosetta Stone Hebrew. If you have a creative mind, you will make all your own differences in the end!

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