What is Particulate Matter (PM), and Does it Affect Air Quality? - Your Particulate Matter Guidebook

by Kieran Berryman September 19, 2024

Particulate Matter 101: What It Is And How Can You Control Its Effects

The United States Environmental Protection Agency (EPA) identifies six criteria air pollutants that contribute to air pollution and negatively impact air quality. Particulate matter (PM) is one of those pollutants. But what is it? And what does it mean for you?

This blog will cover the following topics:

Particulate Matter (PM)
Where PM Can Be Found
Health and Environmental Effects of PM
What You Can Do About PM

Particulate Matter (PM)

Particulate matter is “the term for a mixture of solid particles and liquid droplets found in the air” (PM Basics | EPA). Unlike other criteria pollutants such as O₃ or CO, PM isn’t just one substance or chemical. Rather, it is “a complex mixture of solids and aerosols composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings” (CARB). Essentially, PM is a bunch of different things that float around in the air, such as smoke, dust, pollen, or soot.

Size

Because a similarity in composition doesn’t exist between particulates, PM is generally sorted by size range. These ranges are listed below:

PM1: Particles in this size range are one micron in diameter or smaller; these are generally referred to as “ultrafine” particles or UFPs. Examples of PM1 include:

Particles from volcanic eruptions.
Biological particles.
Road and agricultural dust.
Particles from construction and demolition.

PM2.5: Particles in this size range are two and a half microns in diameter or smaller; these are generally referred to as “fine” particles. Examples of PM2.5 include:

Wildfire smoke.
Combustion particles.
Organic compounds.
Metals.

PM10: Particles in this size range are ten microns in diameter or smaller; these are generally referred to as “coarse” particles. Examples of PM10 include:

Landfill and agricultural off-put.
Smoke from brush/waste burning.
Wind-blown dust from open lands.
Pollens.

When discussing air quality, you will hear people refer to things like PM10 or PM2.5. These are the size ranges listed above. We’ll talk more about this subject below, but different sizes of PM interact with the body and with the environment in different ways. Thus, a distinction between size ranges is generally useful.

Where Can Particulate Matter (PM) Be Found?

Given that PM refers to a size range of particles rather than something specific, there are many sources of PM that span from everyday activities to the byproducts of industrial processes. You may interact with a number of these sources in your day-to-day life or none at all. Either way, it is useful to know what to look out for and where. To communicate this information, I’m going to sort the sources of PM into three categories: outdoor sources, indoor sources, and hyper-local sources.

Outdoor Sources of PM

According to the Utah DEQ, outdoor PM can be produced by primary and secondary sources. Primary sources of PM can include particulate matter emitted from “construction sites, wildfires, wood burning, gravel pits, agricultural activities, dusty roads,” etc. These are things or activities that directly generate PM.

Secondary sources arise “in the atmosphere through complex chemical reactions.” These are substances that float around in the atmosphere and, through a reaction, form PM. Examples of sources that release precursors that lead to these reactions include “power plants, industry, vehicles, small businesses, buildings, homes,” etc.

Because there are so many sources of PM outdoors, it is always a good idea to check the air quality in your area regularly. You can view readings from government sensors at https://gispub.epa.gov/airnow/. Or, you can view readings a little closer to home at https://map.purpleair.com/.

Indoor Sources of PM

Sometimes, poor air quality can feel overwhelming because there are so many factors you can’t control outdoors. Inside your home, however, circumstances are different. To start controlling the air quality in your home, you first have to understand what practices could be helping or hurting your air quality. Below are some common sources of indoor PM you should keep in mind.

The EPA identifies a number of common home activities that contribute to PM. These include, but are not limited to, cooking, some cleaning activities, combustion activities such as burning candles or using a fireplace, biological contaminants produced by pets, pests, or plants, and printers. In addition to PM created indoors, outdoor infiltration is a significant contributor to indoor air quality. This occurs when outside air enters the home through windows, doors, or other unblocked openings (IAQ | EPA).

Hyperlocal Sources of PM

The word “hyperlocal” refers to something that is “limited to a very small geographical area” (Merriam-Webster). We often label our sensors as hyperlocal machines because they only monitor the air that touches them. In this case, the sensors are hyperlocal because their coverage area is limited to a very small geographical area.

A “hyperlocal” source of air pollution or particulate matter is one that only affects a very small geographical area. Some of the above-listed indoor sources of PM can be hyperlocal themselves, such as cooking or printers. However, there are also some common outdoor sources that you should consider, such as smoking, grilling, or trash burning.

These events are on such a small scale that they might not even affect the next block over. However, if they are happening near your home, you’ll want to keep them in mind.

Health and Environmental Effects of Particulate Matter (PM)

So, we’ve established what PM is, that it makes air quality worse, and where it can be found. But what does that mean for you and your environment? Below, we’ll dive deeper into the effects of PM.

Environmental Effects of PM

PM can negatively impact the environment just as much as it can you. PM affects the environment in a few different ways that you might be interested in. According to the EPA’s Health and Environmental Effects of Particulate Matter (PM) page, “particles can be carried over long distances by wind and then settle on ground or water.” The settling of these particles can cause a number of effects listed below:

making lakes and streams acidic.
changing the nutrient balance in coastal waters and large river basins.
depleting the nutrients in soil.
damaging sensitive forests and farm crops.
affecting the diversity of ecosystems.
contributing to acid rain effects.

Health Effects of PM

A number of health effects have been associated with particulate matter in general and with the different size ranges of PM. Below, we’ll list some health effects for the different size ranges of PM.

PM1

There isn’t much research into the effects of PM1; however, there is some. Take this study, for example, which looked at PM1 exposure in children and adolescents. It found that “both short-term and long-term exposure to PM1 is associated with impaired lung function.” As such, the researchers involved in the study recommended that “appropriate protective measures” be taken to mitigate the detrimental effects of PM1.

PM2.5

Of the commonly discussed size ranges of particulate matter, PM2.5 probably gets the most buzz. This is because it has been shown to pose the greatest risk to human health. The California Air Resources Board groups the effects of PM2.5 by length of exposure into two groups: long-term and short-term exposure.

Short-term exposures, which CARB defines as twenty-four hours or less, can cause or aggravate a number of health issues. These include “premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days.”

Long-term exposures, which CARB defines as months to years, have been “linked to premature death, particularly in people who have chronic heart or lung diseases, and reduced lung function growth in children.”

PM10

The largest size range of particulate matter typically discussed, PM10, has the capacity to enter “the upper regions of the lungs.” Once settled on the lung’s surface, the particulates can “induce tissue damage and lung inflammation, impacting respiratory and cardiovascular health” (CARB). These effects can result in:

reduced lung function.
worsening of asthma and other respiratory diseases.
increased hospitalization and emergency department visits.
faster disease progression.
reduced life expectancy.

While all of this does sound grim, there are many things you can do proactively to mitigate your exposure to PM.

What Can I Do About Particulate Matter (PM)?

Given all of the information above, I’m sure you want to know what you can do to mitigate your exposure to PM. The good news is that there are a number of easy things you can do to help with your PM exposure. To start, the EPA says that “the best way to reduce PM is to reduce its sources.” But what does that mean?

Think about all of the sources of PM that were discussed above. Many of those, especially the ones outdoors, you might not have control over. So, the best way to mitigate their effects is to avoid them if possible. But here, the EPA isn’t talking about those types of sources. Rather, they’re talking about things that you can control. Most of these involve indoor sources of PM.

There are some things you can do generally to help with indoor PM. If you are a fan of keeping windows or doors open, make sure there isn’t any outdoor PM coming in that could be affecting your air quality. Additionally, run your HVAC systems to cycle air outside of the home. This will help with any pollutants that are already inside. If you don’t have an HVAC system, you can purchase air purifiers to place around your home. Alternatively, we find that making a DIY box fan air purifier works quite well.

To dive into something a little more specific, let’s take a look at cooking, which is something that most people do every day. Despite what some might believe, it does produce a high amount of PM. However, there are steps you can take to mitigate that PM off-put. When cooking, the EPA suggests:

Using the stove at a lower temperature.
Using cooking oils with higher smoke points.
Using a range hood when available.
Opening windows or doors (when safe) if a range hood is not available.

These methods do not eliminate PM created from cooking, but they do reduce your exposure to it.

Let’s take another example: biological contaminants. These are things like pollen, mold, spores, or pet dander. They originate from biological sources, hence biological. When actions such as sweeping occur, these contaminants get blown up into the air and become airborne PM. To reduce your exposure to this type of PM, the EPA suggests a few things:

Keep your windows sealed on high-pollen days.

Clean frequently: reducing the buildup of these biological sources is one of the best ways to mitigate your exposure.

Cleaning involves vacuuming carpets and furniture at least once a week, if not more often, dusting with a damp cloth, and/or washing bedding with hot water once a week.

Keep your home dry: preventing mold growth, dust mites, and cockroaches reduces the number of sources of PM in your home.

To keep your home dry, ensure your indoor humidity is low, fix any water problems as they arise, and/or install exhaust fans to vent kitchens and bathrooms.
If you have or use ultrasonic humidifiers, clean them according to the manufacturer's specifications and use distilled water.

While that isn’t everything you can do, I hope you have a better understanding of where to start with particulate matter. If you’re ever concerned about the air quality near you, check local readings on the PurpleAir Map!

References

The above article is in no way exhaustive and does not cover every situation you might find yourself in. Below, I’m going to provide full versions of every link I used in this article and sort them by section. To find more information about a certain topic, look below.

Note: This article was originally published 11/28/2022 and updated 09/19/2024.