Issue link: https://hi.iaq.net/i/630729
118 Appendix A reactions Airborne Dust Particles and fibers suspended in the air generally represent a harmless background but can become a nuisance or cause serious health problems under some conditions. Methodology A variety of collection and analytical techniques are available. Dust can be collected by using a pump to draw air through a filter. The filter can then be weighed (gravimetric analysis) or exam- ined under a microscope. Direct readouts of airborne dust are also available (such as using meters such as those equipped with a "scattered light" detector). Using the Results IAQ measurements for airborne dust will be well below occupational and ambient air guidelines except under the most extreme conditions. Unusual types or elevated amounts of particles or fibers can help identify potential exposure problems. Combustion Products Combustion products are released by motor vehicle exhaust, tobacco smoke, and other sources, and contain airborne dust (see the previous section) along with potentially harmful gases such as carbon monoxide and nitrogen oxides. Methodology Direct-reading meters, detector tubes, and passive dosimeters are among the tech- niques most commonly used to measure carbon monoxide and nitrogen oxides. Using the Results Comparison with occupational standards bioaerosols that are heavy enough to fall out onto the agar will be recorded. Using the Results Quantities and types of bioaerosols can vary greatly over time in any given building, making sampling results difficult to interpret. Comparison of relative numbers and types between indoors and outdoors or between complaint areas and background sites can help to establish trends; however, no tolerance levels or absolute guidelines have been established. Low bioaerosol results by themselves are not considered proof that a problem does not exist, for a variety of reasons: ■ the sampling and identification tech- niques used may not be suited to the type(s) of bioaerosols that are present ■ biological growth may have been inactive during the sampling period ■ the analysis technique used may not reveal non-living bioaerosols (e.g., feces, animal parts) that can cause health High-flow indoor particulate sampler. Used to measure particles 10 microns and smaller that are readily inhaled.