Particulate Matter 101: What It Is And How Can You Control Its Effects
The Environment Protection Agency, or EPA, has categorized air pollutants into six categories. These include carbon monoxide, nitrogen oxides, sulfur oxides, lead, ground-level ozone, and particulate matter (PM).
Of these categories, particle pollution, also called Particulate Matter (PM), is the most complex type of air pollutant.
This is because PM consists of several different pollutants that do not share a single source of origin, chemical composition, or even physical state. They can be solid or liquid and can come from natural or artificial sources.
This article addresses the definition of particulate matter, its types, and potential hazards on the human body.
What is Particulate Matter (PM)?
Particulate matter and particle pollution refer to the suspension of solid or liquid pollutants in the air. These microscopic particles can come in a variety of forms and cause harm to living organisms.
Some examples are:
3 Types Of Particulate Matter
Depending on the size of the particles, PM is divisible into three categories: PM10, PM2.5, and PM0.1. In simpler terms, these are also referred to as Coarse Particles, Fine Particles, and Ultra-Fine Particles.
Because there are so many kinds of PM, scientists classify the particles according to their size to make them more convenient. By categorizing them by size, we can also classify them based on their properties.
These properties govern their:
- Transport and removal from the air
- Deposition in the human respiratory organs
- Chemical composition and source of origin
1. PM10 (Coarse Particles)
First, the largest particle size is categorized as PM10. These particles are usually 10 μm in aerodynamic diameter and are called coarse particles.
A few examples of PM10 are:
- Sea salt
- Pollen grains
- Parts of insects or plants
Most of the PM10 is produced mechanically by the breakdown of larger objects. For instance, dust can originate from unpaved roads, construction work, agricultural processes, mining, and so on.
Some particles, such as dust, are big enough to be seen by the naked eye.
2. PM2.5 (Fine Particles)
Particles with an aerodynamic diameter of 2.5 μm or less fall under the category of PM2.5. This is the most well-researched and well-known particle in the pollution category, with several studies about its sources, examples, and impacts on human health.
A few examples of PM2.5 include:
- Metal vapors
- Emissions from factories and power plants
PM2.5 may be produced from natural or artificial sources. The most common processes involved in forming these particles are the condensation of gasses into solids and combustion.
Wildfires are one of the primary natural causes of combustible carbon particles that are 2.5 μm in diameter. Other sources of smoke include vehicles, power plants, factories, and coal burning.
3. PM0.1 (Ultra-Fine Particles)
Finally, the smallest particulate matter with a diameter of less than 0.1 μm is known as PM0.1. While there is little research about this category of particles, they do constitute the most significant portion of pollutant particles.
A few examples of PM0.1 include:
- Heavy metal vapors
- Elemental carbon
- Organic carbon
- Sulfates and nitrates
These particles usually form through a process called nucleation. This is the initial process through which a new material or thermodynamic state forms through rearrangement.
Another essential detail is that PM can be primary or secondary. The primary particles are directly produced by combustion, natural reactions, or human activities. Primary PMs then react with each other in the atmosphere to create secondary particles.
Vaporization of organic compounds and metals by combustion under high pressure gives rise to primary PM0.1. In contrast, particles of ammonium sulfates and ammonium nitrates are produced secondarily due to sulfur dioxide and nitrogen dioxide reacting with oxygen and ammonia.
How Does PM Affect Human Health?
When it comes to particle pollution, all of them are dangerous. Coarse particles such as PM10 are inhalable and can irritate the nose, airways, and eyes. This is especially harmful to vulnerable populations, like pregnant women, elderly, and those with respiratory health concerns.
Meanwhile, finer particles are small enough to enter the human respiratory pathway and diffuse through the thin membranes of alveoli, entering the bloodstream. As such, they are more detrimental to respiratory health and require careful monitoring.
Worried about air quality?
Monitor the Particulate Matter levels around the world with our free, real-time PurpleAir Map or join PurpleAir's mission to make air quality data accessible to everyone by investing in an air quality monitor for your home.
Together, we can be informed and make changes in our daily habits and the community to improve air quality.