Editing Nephelometer (section)

==Nephelometer uses==
{{refimprove section|date=January 2022}}
{{external media | width = 210px | float = right | headerimage= [[File:Wilma Theatre 2013 Particle Falls 004.JPG|210px]] | video1 = [https://www.sciencehistory.org/particle-falls Andrea Polli, ''Particle Falls'', an art installation using a nephelometer to visualize particulate matter] (2013).}}

[[File:Airborne-particulate-size-chart.svg|thumb|Particulate contaminants (size in micrometers).]]
The main uses of nephelometers relate to air quality measurement for pollution monitoring, climate monitoring, and visibility. Airborne particles are commonly either biological contaminants, particulate contaminants, gaseous contaminants, or dust.{{fact|date=January 2022}}

The accompanying chart shows the types and sizes of various particulate contaminants. This information helps understand the character of particulate pollution inside a building or in the ambient air, as well as the cleanliness level in a controlled environment.{{fact|date=January 2022}}

Biological contaminants include mold, fungus, bacteria, viruses, animal dander, dust mites, pollen, human skin cells, cockroach parts, or anything alive or living at one time. They are the biggest enemy of [[indoor air quality]] specialists because they are contaminants that cause health problems. Levels of biological contamination depend on humidity and temperature that supports the livelihood of micro-organisms. The presence of pets, plants, rodents, and insects will raise the level of biological contamination.<ref>{{Cite web |last=US EPA |first=OAR |date=2014-08-14 |title=Biological Pollutants' Impact on Indoor Air Quality |url=https://www.epa.gov/indoor-air-quality-iaq/biological-pollutants-impact-indoor-air-quality |access-date=2025-04-24 |website=www.epa.gov |language=en}}</ref>

=== Sheath air ===
Sheath air is clean filtered air that surrounds the aerosol stream to prevent particulates from circulating or depositing within the optic chamber. Sheath air prevents contamination caused by build-up and deposits, improves response time by containing the sample, and improves maintenance by keeping the optic chamber clean. The nephelometer creates the sheath air by passing air through a zero filter before beginning the sample.{{fact|date=January 2022}}

=== Global radiation balance ===
{{stack|[[File:Radiation Balance.jpg|thumb|Radiation balance (thickness of Earth's atmosphere is greatly exaggerated).]]}}
Nephelometers are also used in global warming studies, specifically measuring the global radiation balance. Three wavelength nephelometers fitted with a backscatter shutter can determine the amount of solar radiation that is reflected back into space by dust and particulate matter. This reflected light influences the amount of radiation reaching the earth's lower atmosphere and warming the planet.{{fact|date=January 2022}}

=== Visibility ===
Nephelometers are also used for measurement of visibility with simple one-wavelength nephelometers used throughout the world by many EPAs. Nephelometers, through the measurement of light scattering, can determine visibility in distance through the application of a conversion factor called <!-- E. L. or Lothar E. -->[[Koschmieder's formula]].{{fact|date=January 2022}}

===Medicine===
{{main|Nephelometry (medicine)}}
In medicine, nephelometry is used to measure immune function. It is also used in clinical microbiology, for preparation of a standardized inoculum (McFarland suspension) for antimicrobial susceptibility testing.<ref>{{Cite web |title=Sensititre™ Nephelometer |url=https://www.thermofisher.com/order/catalog/product/V3011}}</ref><ref>{{Cite journal |last1=Guinet |first1=Roland M. F. |last2=Mazoyer |first2=Marie-Andrée |date=1983 |title=Laser nephelometric semi-automated system for rapid bacterial susceptibility testing |url=https://academic.oup.com/jac/article-lookup/doi/10.1093/jac/12.3.257 |journal=Journal of Antimicrobial Chemotherapy |language=en |volume=12 |issue=3 |pages=257–263 |doi=10.1093/jac/12.3.257 |pmid=6630109 |issn=0305-7453|url-access=subscription }}</ref>

===Fire detection===
{{main|Aspirating smoke detector}}
Gas-phase nephelometers are also used in the detection of [[smoke]] and other particles of [[combustion]]. In such use, the apparatus is referred to as an [[aspirated smoke detector]]. These have the capability to detect extremely low particle concentrations (to 0.005%) and are therefore highly suitable to protecting sensitive or valuable electronic equipment, such as [[mainframe computer]]s and [[telephone switch]]es.{{fact|date=January 2022}}