An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be generated from natural or human causes. The term aerosol commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from atomizers, smoke, dust, sprayed pesticides, and medical treatments for respiratory illnesses.
A nephelometer or aerosol photometer is an instrument for measuring the concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam and a light detector set to one side of the source beam. Particle density is then a function of the light reflected into the detector from the particles. To some extent, how much light reflects for a given density of particles is dependent upon properties of the particles such as their shape, color, and reflectivity. Nephelometers are calibrated to a known particulate, then use environmental factors (k-factors) to compensate lighter or darker colored dusts accordingly. K-factor is determined by the user by running the nephelometer next to an air sampling pump and comparing results. There are a wide variety of research-grade nephelometers on the market as well as open source varieties.
A particle counter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water and chemicals. Particle counters are used in a variety of applications in support of clean manufacturing practices, industries include: electronic components and assemblies, pharmaceutical drug products and medical devices, and industrial technologies such as oil and gas.
A particulate matter sampler is an instrument for measuring the properties of particulates in the ambient air.
Bioaerosols are a subcategory of particles released from terrestrial and marine ecosystems into the atmosphere. They consist of both living and non-living components, such as fungi, pollen, bacteria and viruses. Common sources of bioaerosols include soil, water, and sewage.
In granulometry, the particle-size distribution (PSD) of a powder, or granular material, or particles dispersed in fluid, is a list of values or a mathematical function that defines the relative amount, typically by mass, of particles present according to size. Significant energy is usually required to disintegrate soil, etc. particles into the PSD that is then called a grain size distribution.
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of Earth's surface. With an operationally defined thickness between 1 and 1,000 μm (1.0 mm), the SML has physicochemical and biological properties that are measurably distinct from underlying waters. Recent studies now indicate that the SML covers the ocean to a significant extent, and evidence shows that it is an aggregate-enriched biofilm environment with distinct microbial communities. Because of its unique position at the air-sea interface, the SML is central to a range of global marine biogeochemical and climate-related processes.
Tihomir Novakov, Ph.D known also as Tica Novakov was a Serbian-born American physicist. As a scientist, Novakov is known for his black carbon, air quality, and climate change research. James Hansen dubbed him "the godfather of black carbon".
In the physics of aerosols, aerosol impaction is the process in which particles are removed from an air stream by forcing the gases to make a sharp bend. Particles above a certain size possess so much momentum that they can not follow the air stream and strike a collection surface, which is available for later analysis of mass and composition. Removal of particles from an air-stream by impaction followed by mass and composition analysis has always been a different approach as to filter sampling, yet has been little utilized for routine analysis because of lack of suitable analytical methods.
Multi-Angle light scattering describes a technique for measuring the light scattered by a sample into a plurality of angles. It is used for determining both the absolute molar mass and the average size of molecules in solution, by detecting how they scatter light. A collimated beam from a laser source is most often used, in which case the technique can be referred to as multiangle laser light scattering (MALLS). The insertion of the word laser was intended to reassure those used to making light scattering measurements with conventional light sources, such as Hg-arc lamps that low-angle measurements could now be made.
A scanning mobility particle sizer (SMPS) is an analytical instrument that measures the size and number concentration of aerosol particles with diameters from 2.5 nm to 1000 nm. They employ a continuous, fast-scanning technique to provide high-resolution measurements.
Particulates or atmospheric particulate matter are microscopic particles of solid or liquid matter suspended in the air. The term aerosol refers to the particulate/air mixture, as opposed to the particulate matter alone, though it is sometimes defined as a subset of aerosol terminology. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.
An aethalometer is an instrument for measuring the concentration of optically absorbing (‘black’) suspended particulates in a gas colloid stream; commonly visualized as smoke or haze, often seen in ambient air under polluted conditions. The word aethalometer is derived from the Classical Greek verb aethaloun, meaning "to blacken with soot". The aethalometer, a device used for measuring black carbon in atmospheric aerosols, was initially deployed in 1980 and was first commercialized by Magee Scientific.
Aerosol mass spectrometry is the application of mass spectrometry to the analysis of the composition of aerosol particles. Aerosol particles are defined as solid and liquid particles suspended in a gas (air), with size range of 3 nm to 100 μm in diameter and are produced from natural and anthropogenic sources, through a variety of different processes that include wind-blown suspension and combustion of fossil fuels and biomass. Analysis of these particles is important owing to their major impacts on global climate change, visibility, regional air pollution and human health. Aerosols are very complex in structure, can contain thousands of different chemical compounds within a single particle, and need to be analysed for both size and chemical composition, in real-time or off-line applications.
A Particle mass analyser(PMA) is an instrument for classifying aerosol particles according to their mass-to-charge ratio using opposing electrical and centrifugal forces. This allows the classifier to select particles of a specified mass-to-charge ratio independent of particle shape.
A tapered element oscillating microbalance (TEOM) is an instrument used for real-time detection of aerosol particles by measuring their mass concentration. It makes use of a small vibrating glass tube whose oscillation frequency changes when aerosol particles are deposited on it increasing its inertia. TEOM-based devices have been approved by the U.S. Environmental Protection Agency for environmental air quality monitoring, and by the U.S. Mine Safety and Health Administration for monitoring coal dust exposure for miners to prevent several respiratory diseases.
The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) was a five-year scientific research program that investigated aspects of phytoplankton dynamics in ocean ecosystems, and how such dynamics influence atmospheric aerosols, clouds, and climate. The study focused on the sub-arctic region of the North Atlantic Ocean, which is the site of one of Earth's largest recurring phytoplankton blooms. The long history of research in this location, as well as relative ease of accessibility, made the North Atlantic an ideal location to test prevailing scientific hypotheses in an effort to better understand the role of phytoplankton aerosol emissions on Earth's energy budget.
Workplace exposure monitoring is the monitoring of substances in a workplace that are chemical or biological hazards. It is performed in the context of workplace exposure assessment and risk assessment. Exposure monitoring analyzes hazardous substances in the air or on surfaces of a workplace, and is complementary to biomonitoring, which instead analyzes toxicants or their effects within workers.
Particulate pollution is pollution of an environment that consists of particles suspended in some medium. There are three primary forms: atmospheric particulate matter, marine debris, and space debris. Some particles are released directly from a specific source, while others form in chemical reactions in the atmosphere. Particulate pollution can be derived from either natural sources or anthropogenic processes.
An Andersen sampler or Andersen impactor is a cascade impactor used to determine the amount of viable pathogens in a given area, in particular bacteria and fungi. Unlike real-time electronic particle counters, the Andersen sampler imparts pathogens on petri dishes, which require incubation. Thus, calculation of the contaminated air requires working backwards from the resulting pathogen growth in each dish.
