Ultrafine particles (UFPs) are
particulate matter of
nanoscale
The nanoscopic scale (or nanoscale) usually refers to structures with a length scale applicable to nanotechnology, usually cited as 1–100 nanometers (nm). A nanometer is a billionth of a meter. The nanoscopic scale is (roughly speaking) a lo ...
size (less than 0.1
μm or 100
nm in diameter).
[
] Regulations do not exist for this size class of ambient
air pollution
Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...
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.
In the EU UFP's in ambient air are empirically defined by
technical specification The important detail is the definition of size, stated: "The lower and upper sizes considered within this document are 7 nm and a few micrometres, respectively". Although the most common referral to UFP is "less than 0.1μm", this is incorrect for ambient air in the EU.
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
A condensation particle counter or CPC is a particle counter that detects and counts aerosol particles by first enlarging them by using the particles as nucleation centers to create droplets in a supersaturated gas. Aerosol Measurement: Princip ...
, in which particles are mixed with alcohol vapor and then cooled, allowing the vapor to condense around them, after which they are counted using a light scanner.
[
] UFPs are both manufactured and naturally occurring. UFPs are the main constituent of airborne particulate matter. Owing to their large 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
Smoke is a suspension of airborne particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product ...
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
Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types ...
study found harmful ultrafine particles from the takeoffs and landings at
Los Angeles International Airport
Los Angeles International Airport , commonly referred to as LAX (with each letter pronounced individually), is the primary international airport serving Los Angeles, California and its surrounding metropolitan area. LAX is located in the W ...
to be of much greater magnitude than previously thought. There are a multitude of indoor sources that include but are not limited to
laser printers
Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" to ...
,
fax machines
Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer o ...
,
photocopiers
A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers u ...
, the peeling of
citrus fruits
''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is nativ ...
,
cooking
Cooking, cookery, or culinary arts is the art, science and craft of using heat to Outline of food preparation, prepare food for consumption. Cooking techniques and ingredients vary widely, from grilling food over an open fire to using electric ...
,
tobacco smoke
Tobacco smoke is a sooty aerosol produced by the incomplete combustion of tobacco during the tobacco smoking, smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to abo ...
, penetration of contaminated outdoor air,
chimney
A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typic ...
cracks and
vacuum cleaners
A vacuum cleaner, also known simply as a vacuum or a hoover, is a device that causes suction in order to remove dirt from floors, upholstery, draperies, and other surfaces. It is generally electrically driven.
The dirt is collected by either a ...
.
[
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
A nanostructure is a structure of intermediate size between microscopic and molecular structures. Nanostructural detail is microstructure at nanoscale.
In describing nanostructures, it is necessary to differentiate between the number of dime ...
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
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. and carbon nanotubes
A scanning tunneling microscopy image of a single-walled carbon nanotube
Rotating single-walled zigzag carbon nanotube
A carbon nanotube (CNT) is a tube made of carbon with diameters typically measured in nanometers.
''Single-wall carbon nan ...
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
A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...
.
Exposure, risk, and health effects
The main exposure to UFPs is through inhalation. Owing to their size, UFPs are considered to be respirable particles. Contrary to the behaviour of inhaled PM10 and PM2.5, ultrafine particles are deposited in the lungs, where they have the ability to penetrate tissue and undergo interstitialization, or to be absorbed directly into the bloodstream — and therefore are not easily removed from the body and may have immediate effect. Exposure to UFPs, even if components are not very toxic, may cause oxidative stress
Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily Detoxification, detoxify the reactive intermediates or to repair the resulting damage. Disturbances ...
, inflammatory mediator release, and could induce heart disease, lung disease, and other systemic effects.
A robust association has been observed between fine particulate levels and lung cancer, and cardiopulmonary disease. The exact mechanism through which UFP exposure leads to health effects remains to be elucidated, but effects on Blood pressure may play a role. It has recently been reported that UFP is associated with an increase in blood pressure
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...
in schoolchildren with the smallest particles inducing the largest effect. According to research, infants whose mothers were exposed to higher levels of UFPs during pregnancy are much more likely to develop asthma.
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
An office is a space where an Organization, organization's employees perform Business administration, administrative Work (human activity), work in order to support and realize objects and Goals, plans, action theory, goals of the organizati ...
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.
Some sizes of UFPs may be filtered from the air using ULPA
ULPA is an acronym for "Ultra-low Penetration Air (filter)". An ULPA filter can remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a minimum particle penetration size of 120 nanometres (0.12 Â ...
filters.
Regulation and legislation
As the nanotechnology
Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal o ...
industry has grown, nanoparticle
A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 1 ...
s have brought UFPs more public and regulatory attention. UFP risk assessment research is still in the very early stages. There are continuing debates about whether to regulate UFPs and how to research and manage the health risks they may pose.[
][
] As of March 19, 2008, the EPA does not yet regulate or research ultrafine particles, but has drafted a Nanomaterial Research Strategy, open for independent, external peer review beginning February 7, 2008 (Panel review on April 11, 2008). There is also debate about how the European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
(EU) should regulate UFPs.
Political disputes
There is political dispute between China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
and South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
on Ultrafine dust. South Korea claims that about 80% of ultrafine dust comes from China, and China and South Korea should cooperate to reduce the level of fine dust. China, however, argues that Chinese government have already implemented its policy regarding ecological environment. According to China’s government, its quality of air has been improved more than 40% since 2013. However, the air pollution in South Korea got worse. Therefore, the dispute between China and South Korea has become political. In March 2019, Seoul Research Institute of Public Health and Environment said that 50% to 70% of the fine dust is from China, therefore China is responsible for the air pollution in South Korea. This dispute provokes dispute among citizens as well.
In July 2014, China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
's paramount leader
Paramount leader () is an informal term for the most important political figure in the People's Republic of China (PRC). The paramount leader typically controls the Chinese Communist Party (CCP) and the People's Liberation Army (PLA), often hol ...
Xi Jinping
Xi Jinping ( ; ; ; born 15 June 1953) is a Chinese politician who has served as the general secretary of the Chinese Communist Party (CCP) and chairman of the Central Military Commission (CMC), and thus as the paramount leader of China, s ...
and the South Korean government
The Government of South Korea is the union government of the South Korea, Republic of Korea, created by the Constitution of South Korea as the executive, legislative and judicial authority of the republic. The president acts as the head of sta ...
agreed to enforce Korea-China Cooperative Project, regarding Sharing of observation data on air pollutions, joint research on an air pollution forecast model and air pollution source identification, and human resources exchanges, etc. Followed by this agreement, in 2018, China and South Korea signed China-Korea Environmental Cooperation Plan to resolute environmental issues. China Research Academy of Environmental Studies (CRAES) in Beijing is developing a building for China-Korea Environmental Cooperation Center including office building and laboratory building. Based on this cooperation, South Korea already sent 10 experts on environments to China for research, and China will also send more experts for long-term research. By this bilateral relations, China and Republic of Korea are seeking resolution on air pollution in North East Asia region, and seeks international security.
See also
* Diesel particulate matter
*Nanostructures
A nanostructure is a structure of intermediate size between microscopic and molecular structures. Nanostructural detail is microstructure at nanoscale.
In describing nanostructures, it is necessary to differentiate between the number of dime ...
References
{{reflist, 2
Particulates
*