Ultrafine particles (UFPs) are nanoscale, less than 100 nanometres. 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.UFPs are both manufactured and naturally occurring. UFPs are the main constituent of airborne particulate matter. Due to there 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 particle 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. 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 extorted 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.

Exposure, Risk, and Health Effects:

The main exposure to UFPs is through inhalation. Due to their size, UFPs are considered to be respirable particles and are able to travel deep within the lung with the potential to penetrate tissue and undergo interstitialization and therefore are not easily removed from the body. Exposure to UFPs, even if components are not very toxic, may cause oxidative stress, inflammatory mediator release, and could induce lung disease and other systemic effects.

There is a range of potential human exposures that include occupational, due to the direct manufacturing process or a byproduct from an industrial or office environment, as well as incidental,from contaminated outdoor air and other byproduct emissions. In order to quantify exposure and risk, both in vivo and in vitro studies of various UFP species are currently being done using a variety of animal models including mouse, rat, and fish. These studies aim to establish toxicological profiles necessary for risk assessment, risk management, and potential regulation and legislation.