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Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 100 nanometres in diameter).〔 〕 Regulations do not exist for this size class of ambient air pollution particles, which are far smaller than the regulated PM10 and PM2.5 particle classes and are believed to have several more aggressive health implications than those classes of larger particulates.〔 〕 There are two main divisions that categorize types of UFPs. UFPs can either be carbon-based or metallic, and then can be further subdivided by their magnetic properties. Electron microscopy and special physical lab conditions allow scientists to observe UFP morphology.〔 Airborne UFPs can be measured using a condensation particle counter, in which particles are mixed with alcohol vapor and then cooled allowing the vapor to condense around them which are then counted using a light scanner.〔 〕 UFPs are both manufactured and naturally occurring. UFPs are the main constituent of airborne particulate matter. Due to their numerous quantity and ability to penetrate deep within the lung, UFPs are a major concern for respiratory exposure and health.〔 〕 == Sources and applications == UFPs are both manufactured and naturally occurring. Hot volcanic lava, ocean spray, and smoke are common natural UFPs sources. UFPs can be intentionally fabricated as are fine particles to serve a vast range of applications in both medicine and technology. Other UFPs are byproducts, like emissions, from specific processes, combustion reactions, or equipment such as printer toner and automobile exhaust.〔 〕〔 〕 In 2014, an air quality study found harmful ultrafine particles from the takeoffs and landings at Los Angeles International Airport to be of much greater magnitude than previously thought.〔Weikel, Dan and Barboza, Tony (May 29, 2014) ("Planes' exhaust could be harming communities up to 10 miles from LAX" ) ''Los Angeles Times''〕 There are a multitude of indoor sources that include but are not limited to laser printers, fax machines, photocopiers, the peeling of citrus fruits, cooking, tobacco smoke, penetration of contaminated outdoor air, chimney cracks and vacuum cleaners.〔 UFPs have a variety of applications in the medical and technology fields. They are used in diagnostic imagining, and novel drug delivery systems that include targeting the circulatory system, and or passage of the blood brain barrier to name just a few.〔 〕 Certain UFPs like silver based nanostructures have antimicrobial properties that are exploited in wound healing and internal instrumental coatings among other uses, in order to prevent infections.〔 〕 In the area of technology, carbon based UFPs have a plethora of applications in computers. This includes the use of graphene and carbon nanotubes in electronic as well as other computer and circuitry components. Some UFPs have characteristics similar to gas or liquid and are useful in powders or lubricants.〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ultrafine particle」の詳細全文を読む スポンサード リンク
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