Particulate pollution

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Particulate pollution is pollution of an environment that consists of particles suspended in some medium. There are three primary forms: atmospheric particulate matter, [1] marine debris, [2] and space debris. [3] 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.


Atmospheric particulate matter

Average global distribution of particulate matter (PM2.5) concentrations (2001-2006). 483897main Global-PM2.5-map.JPG
Average global distribution of particulate matter (PM2.5) concentrations (2001-2006).

Atmospheric particulate matter, also known as particulate matter, or PM, describes solids and/or liquid particles suspended in a gas, most commonly the Earth's atmosphere. [1] Particles in the atmosphere can be divided into two types, depending on the way they are emitted. Primary particles, such as mineral dust, are emitted into the atmosphere. [4] Secondary particles, such as ammonium nitrate, are formed in the atmosphere through gas-to-particle conversion. [4]


Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray. Human activities, such as the burning of fossil fuels in vehicles, [5] stubble burning, power plants, road dust, wet cooling towers in cooling systems and various industrial processes, also generate significant amounts of particulates. Coal combustion in developing countries is the primary method for heating homes and supplying energy. Because salt spray over the oceans is the overwhelmingly most common form of particulate in the atmosphere, anthropogenic aerosols—those made by human activities—currently account for about 10 percent of the total mass of aerosols in our atmosphere. [6]

Marine debris

Marine debris and marine aerosols refer to particulates suspended in a liquid, usually water on the Earth's surface. Particulates in water are a kind of water pollution measured as total suspended solids, a water quality measurement listed as a conventional pollutant in the U.S. Clean Water Act, a water quality law. [7] Notably, some of the same kinds of particles can be suspended both in air and water, and pollutants specifically may be carried in the air and deposited in water, or fall to the ground as acid rain. [8] The majority of marine aerosols are created through the bubble bursting of breaking waves and capillary action on the ocean surface due to the stress exerted from surface winds. [2] Among common marine aerosols, pure sea salt aerosols are the major component of marine aerosols with an annual global emission between 2,000-10,000 teragrams annually. [2] Through interactions with water, many marine aerosols help to scatter light, and aid in cloud condensation and ice nuclei (IN); thus, affecting the atmospheric radiation budget. [2] When they interact with anthropogenic pollution, marine aerosols can affect biogeochemical cycles through the depletion of acids such as nitric acid and halogens. [2]

Space debris

Space debris describes particulates in the vacuum of outer space, specifically particles originating from human activity that remain in geocentric orbit around the Earth. The International Association of Astronauts define space debris as "any man-made Earth orbiting object which is non-functional with no reasonable expectation of assuming or resuming its intended function or any other function for which it is or can be expected to be authorized, including fragments and parts thereof". [3]

Space debris is classified by size and operational purpose, and divided into four main subsets: inactive payloads, operational debris, fragmentation debris and microparticulate matter. [3] Inactive payloads refer to any launched space objects that have lost the capability to reconnect to its corresponding space operator; thus, preventing a return to Earth. [9] In contrast, operational debris describes the matter associated with the propulsion of a larger entity into space, which may include upper rocket stages and ejected nose cones. [9] Fragmentation debris refers to any object in space that has become dissociated from a larger entity by means of explosion, collision or deterioration. [10] Microparticulate matter describes space matter that typically cannot be seen singly with the naked eye, including particles, gases, and spaceglow. [9]

In response to research that concluded that impacts from Earth orbital debris could lead to greater hazards to spacecraft than the natural meteoroid environment, NASA began the orbital debris program in 1979, initiated by the Space Sciences branch at Johnson Space Center (JSC). [11] Beginning with an initial budget of $70,000, the NASA orbital debris program began with the initial goals of characterizing hazards induced by space debris and creating mitigation standards that would minimize the growth of the orbital debris environment. [12] By 1990, the NASA orbital debris program created a debris monitoring program, which included mechanisms to sample the low Earth orbit (LEO) environment for debris as small as 6mm using the Haystack X-band ground radar. [11]


Particulate pollution is observed around the globe in varying sizes and compositions and is the focus of many epidemiological studies. Particulate matter (PM) is generally classified into two main size categories: PM10 and PM2.5. PM10, also known as coarse particulate matter, consists of particles 10 micrometers (μm) and smaller, while PM2.5, also called fine particulate matter, consists of particles 2.5 μm and smaller. [13] Particles 2.5 μm or smaller in size are especially notable as they can be inhaled into the lower respiratory system, and with enough exposure, absorbed into the bloodstream. Particulate pollution can occur directly or indirectly from a number of sources including, but not limited to: agriculture, automobiles, construction, forest fires, chemical pollutants, and power plants. [14]

Exposure to particulates of any size and composition may occur acutely over a short duration, or chronically over a long duration. [15] Particulate exposure has been associated with adverse respiratory symptoms ranging from irritation of the airways, aggravated asthma, coughing, and difficulty breathing from acute exposure to symptoms such as irregular heartbeat, lung cancer, kidney disease, chronic bronchitis, and premature death in individuals who suffer from pre-existing cardiovascular or lung diseases due to chronic exposure. [13] The severity of health effects generally depends upon the size of the particles as well as the health status of the individual exposed; older adults, children, pregnant women, and immunocompromised populations are at the greatest risk for adverse health outcomes. [16] Short-term exposure to particulate pollution has been linked to adverse health impacts. [17] [18]

As a result, the US Environmental Protection Agency (EPA) and various health agencies around the world have established thresholds for concentrations of PM2.5 and PM10 that are determined to be acceptable. However, there is no known safe level of exposure and thus, any exposure to particulate pollution is likely to increase an individual's risk of adverse health effects. [19] In European countries, air quality at or above 10 micrograms per cubic meter of air (μg/m3) for PM2.5 increases the all-causes daily mortality rate by 0.2-0.6% and the cardiopulmonary mortality rate by 6-13%. [19]

Worldwide, PM10 concentrations of 70μg/m3 and PM2.5 concentrations of 35μg/m3 have been shown to increase long-term mortality by 15%. [13] More so, approximately 4.2 million of all premature deaths observed in 2016 occurred due to airborne particulate pollution, 91% of which occurred in countries with low to middle socioeconomic status. Of these premature deaths, 58% were attributed to strokes and ischaemic heart diseases, 8% attributed to COPD (Chronic Obstructive Pulmonary Disease), and 6% to lung cancer. [20]

In 2006, the EPA conducted air quality designations in all 50 states, denoting areas of high pollution based on criteria such as air quality monitoring data, recommendations submitted by the states, and other technical information; and reduced the National Ambient Air Quality Standard for daily exposure to particulates in the 2.5 micrometers and smaller category from 15μg/m3 to 12μg/m3 in 2012. [21] As a result, U.S. annual PM2.5 averages have decreased from 13.5 µg/m3 to 8.02 µg/m3, between 2000 and 2017. [22]

Related Research Articles

Aerosol colloid of fine solid particles or liquid droplets, in air or another gas

An aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog, dust, forest exudates and geyser steam. Examples of anthropogenic aerosols are haze, particulate air pollutants and smoke. The liquid or solid particles have diameters typically <1 μm; larger particles with a significant settling speed make the mixture a suspension, but the distinction is not clear-cut. In general conversation, aerosol usually refers to an aerosol spray that delivers a consumer product from a can or similar container. Other technological applications of aerosols include dispersal of pesticides, medical treatment of respiratory illnesses, and combustion technology. Diseases can also spread by means of small droplets in the breath, also called aerosols.

Tropospheric ozone constituent gas of the troposphere

Ozone (O3) is a trace gas of the troposphere, with an average concentration of 20-30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas. Ozone is also an important constituent of the stratosphere, where the ozone layer exists which is located between 10 and 50 kilometers about the earths surface. The troposphere is the lowest layer of the Earth's atmosphere. It extends from the ground up to a variable height of approximately 14 kilometers above sea level. Ozone is least concentrated in the ground layer (or planetary boundary layer) of the troposphere. Ground level or tropospheric ozone is created by chemical reactions between oxides of nitrogen (NOx gases) and volatile organic compounds (VOCs). The combination of these chemicals in the presence of sunlight form ozone. Its concentration increases as height above sea level increases, with a maximum concentration at the tropopause. About 90% of total ozone in the atmosphere is in the stratosphere, and 10% is in the troposphere. Although tropospheric ozone is less concentrated than stratospheric ozone, it is of concern because of its health effects. Ozone in the troposphere is considered a greenhouse gas, and may contribute to global warming.

Indoor air quality Air quality within and around buildings and structures

Indoor air quality (IAQ) is the air quality within and around buildings and structures. IAQ is known to affect the health, comfort and well-being of building occupants. Poor indoor air quality has been linked to sick building syndrome, reduced productivity and impaired learning in schools.

Nephelometer Instrument for measuring the concentration of suspended particulates

A nephelometer 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.

Diesel exhaust

Diesel exhaust is the gaseous exhaust produced by a diesel type of internal combustion engine, plus any contained particulates. Its composition may vary with the fuel type or rate of consumption, or speed of engine operation, and whether the engine is in an on-road vehicle, farm vehicle, locomotive, marine vessel, or stationary generator or other application.

Black carbon

Chemically, black carbon (BC) is a component of fine particulate matter. Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuels, biofuel, and biomass, and is emitted in both anthropogenic and naturally occurring soot. Black carbon causes human morbidity and premature mortality.

Criteria air Pollutants (CAP), or criteria pollutants, are a set of air pollutants that cause smog, acid rain, and other health hazards. CAPs are typically emitted from many sources in industry, mining, transportation, electricity generation and agriculture. In many cases they are the products of the combustion of fossil fuels or industrial processes.

Pollution in China

Pollution in China is one aspect of the broader topic of environmental issues in China. Various forms of pollution have increased as China has industrialised, which has caused widespread environmental health problems.

Air pollution Introduction of particulates, biological molecules, or other harmful materials into the Earths atmosphere

Air pollution occurs when harmful or excessive quantities of substances including gases, particulates, and biological molecules are introduced into Earth's atmosphere. It may cause diseases, allergies and even death to humans; it may also cause harm to other living organisms such as animals and food crops, and may damage the natural or built environment. Both human activity and natural processes can generate air pollution.

The sea surface microlayer (SML) is the top 1000 micrometers of the ocean surface. It is the boundary layer where all exchange occurs between the atmosphere and the ocean. The chemical, physical, and biological properties of the SML differ greatly from the sub-surface water just a few centimeters beneath.

Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm 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. In the EU UFP's in ambient air are empirically defined by a 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.

Pollution in California

Pollution in California relates to the degree of pollution in the air, water, and land of the state of California. Pollution is defined as the addition of any substance or any form of energy to the environment at a faster rate than it can be dispersed, diluted, decomposed, recycled, or stored in some harmless form. The combination of three main factors are the cause of notable unhealthy levels of air pollution in California: the activities of over 39 million people, a mountainous terrain that traps pollution, and a warm climate that helps form ozone and other pollutants. Eight of the ten cities in the US with the highest year-round concentration of particulate matter between 2013 and 2015 were in California, and seven out of the ten cities in the US with the worst ozone pollution were also in California. Studies show that pollutants prevalent in California are linked to several health issues, including asthma, lung cancer, birth complications, and premature death. In 2016, Bakersfield, California recorded the highest level of airborne pollutants of any city in the United States.

Air pollution in Mexico City

Air Pollution in Mexico City has been a concerning issue to all citizens and members of the health departments for some time now. In the 20th century, Mexico City's population rapidly increased as industrialization brought thousands of migrants from all over the world.". Such a rapid and unexpected growth led to the UN declaring Mexico City as the most polluted city in the world in 1992. This is perhaps due to Mexico City's high altitude, its oxygen levels are 25% lower and fuels do not combust completely. But it is important to mention that proliferation of vehicles, rapid industrial growth and the population boom are considered the main causes of this situation. The Mexican government has several active plans to try to reduce the emission levels that requires citizen participation, some of which include vehicular restrictions, increase of green areas and expanding bicycle accessibility.

Particulates microscopic solid or liquid matter suspended in the Earths atmosphere

Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in addition to direct inhalation.

Air pollution in Delhi

The air quality in Delhi, the capital territory of India, according to a WHO survey of 1650 world cities, is the worst of any major city in the world. It also affects the districts around Delhi Air pollution in India is estimated to kill about 2.5 million people every year; it is the fifth largest killer in India. India has the world's highest death rate from chronic respiratory diseases and asthma, according to the WHO. In Delhi, poor quality air irreversibly damages the lungs of 2.2 million or 50 percent of all children.

Air quality guideline is an annual mean concentration guideline for particulate matter from the World Health Organization. The guideline stipulates that PM2.5 not exceed 10 μg/m3 annual mean, or 25 μg/m3 24-hour mean; and that PM10 not exceed 20 μg/m3 annual mean, or 50 μg/m3 24-hour mean.

Air pollution in Taiwan

Air pollution in Taiwan is mostly derived from sources of domestic combustion, primarily the burning of fossil fuels. Taiwan's topography has been noted to be a contributing factor to its air pollution problem, leading to poor dispersal and trapping pollutants. Taipei, Taiwan's capital and largest city for example, is surrounded by mountains, and other industrial centers along the northern and western coasts of Taiwan are surrounded by high mountains.

Plankton, Aerosol, Cloud, ocean Ecosystem

Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) is a NASA Earth-observing satellite mission that will continue and advance observations of global ocean color, biogeochemistry, and ecology, as well as carbon cycle, aerosols and clouds. PACE data will be used to identify the extent and duration of algal blooms known as phytoplankton and improve understanding of air quality. These and other uses of PACE data will benefit the economy and society, especially sectors that rely on water quality, fisheries and food security.

Multi-Angle Imager for Aerosols

The Multi-Angle Imager for Aerosols (MAIA) instrument is currently in development to support an investigation aimed at understanding the linkages between different types of airborne particles and human health. MAIA's twin-camera instrument will make radiometric and polarimetric measurements needed to characterize the sizes, compositions and quantities of particulate matter in air pollution. As part of the MAIA investigation, researchers will combine MAIA measurements with population health records to better understand the connections between aerosol pollutants and health problems such as adverse birth outcomes, cardiovascular and respiratory diseases, and premature deaths.

Kimberly Prather is an American scientist who is an Atmospheric Chemist, Distinguished Chair in Atmospheric Chemistry, and a Distinguished Professor at the Scripps Institution of Oceanography and Department of Chemistry and Biochemistry at UC San Diego. Her work focuses on how humans are influencing the atmosphere and climate. In 2019, she was elected as a member of the National Academy of Engineering. She is an elected Fellow of the American Geophysical Union, the American Association for the Advancement of Science, and the American Academy of Arts and Sciences.


  1. 1 2 Perrino, Cinzia (2010). "Atmospheric particulate matter". Biophysics and Bioengineering Letters. 3 (1). ISSN   2037-0199.
  2. 1 2 3 4 5 Fuzzi, S.; Baltensperger, U.; Carslaw, K.; Decesari, S.; Denier van der Gon, H.; Facchini, M. C.; Fowler, D.; Koren, I.; Langford, B. (2015). "Particulate matter, air quality and climate: lessons learned and future needs". Atmospheric Chemistry and Physics. 15 (14): 8217–8299. doi:10.5194/acp-15-8217-2015. ISSN   1680-7316.
  3. 1 2 3 Chaddha, Shane (2010). "Space Debris Mitigation". SSRN Electronic Journal. doi:10.2139/ssrn.1586539. ISSN   1556-5068.
  4. 1 2 Giere, R.; Querol, X. (2010). "Solid Particulate Matter in the Atmosphere". Elements. 6 (4): 215–222. doi:10.2113/gselements.6.4.215. ISSN   1811-5209.
  5. Omidvarborna; et al. (2015). "Recent studies on soot modeling for diesel combustion". Renewable and Sustainable Energy Reviews. 48: 635–647. doi:10.1016/j.rser.2015.04.019.
  6. Hardin, Mary; Kahn, Ralph. "Aerosols and Climate Change".
  7. U.S. Clean Water Act, sec. 304(a)(4), 33 U.S.C. § 1314(a)(4).
  8. EPA,OAR, US. "Health and Environmental Effects of Particulate Matter (PM) | US EPA". US EPA. Retrieved 2018-09-26.
  9. 1 2 3 Baker, H.A. (1989). Space Debris: Legal and Policy Implications. Dordrecht, The Netherlands: Martinus Nijhoff Publishers. p. 4. ISBN   0-7923-0166-8.
  10. Committee on Space Debris, National Research Council (1995). Orbital Debris: A Technical Assessment. National Academies Press. p. 25. ISBN   0309051258.
  11. 1 2 Limiting Future Collision Risk to Spacecraft: An Assessment of NASA's Meteoroid and Orbital Debris Programs. Washington: National Academies Press. 2011. p. 7. ISBN   0309219779.
  12. D.S.F. Portree, J.P. Loftus (1999). Orbital Debris: A Chronology. Washington: NASA. p. 29.
  13. 1 2 3 "WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide, and sulfur dioxide".
  14. "Particulate Matter (PM) Basics".
  15. "Health and Environmental Effects of Particulate Matter".
  16. "Particulate Pollution and Your Health".
  17. Deryugina, Tatyana; Heutel, Garth; Miller, Nolan H.; Molitor, David; Reif, Julian (2019). "The Mortality and Medical Costs of Air Pollution: Evidence from Changes in Wind Direction". American Economic Review. 109 (12): 4178–4219. doi:10.1257/aer.20180279. ISSN   0002-8282.
  18. Di, Qian; Dai, Lingzhen; Wang, Yun; Zanobetti, Antonella; Choirat, Christine; Schwartz, Joel D.; Dominici, Francesca (2017-12-26). "Association of Short-term Exposure to Air Pollution With Mortality in Older Adults". JAMA. 318 (24): 2446–2456. doi:10.1001/jama.2017.17923. ISSN   0098-7484.
  19. 1 2 "Health Effects of Particulate Matter" (PDF).
  20. "Ambient air quality and health".
  21. "Air Quality Standards for PM 2.5".
  22. "Particulate Matter Trends".