You’ve likely seen the term “PM2.5” in news headlines, science articles, or weather apps, but never thought much of it. Besides creating hazy skies and obscuring visibility, this air pollutant can also cause a range of severe and sometimes fatal illnesses, the U.S. Environmental Protection Agency (EPA) reports. But what is PM2.5 exactly, and how does it affect human health? More importantly, how can you reduce your exposure to it?
PM2.5 is a group of particulate matter with a diameter of 2.5 microns or less. Often referred to as fine particulate matter or soot, these microscopic particles usually remain suspended in the air but are so small that they can only be seen individually with an electron microscope. However, they can form a visible haze in the atmosphere at high concentrations.
According to the California Air Resources Board (CARB), PM2.5 isn’t a single pollutant but rather a complex mix of fine solid and/or liquid particles, including:
*Gases are only included as precursors; they aren’t PM2.5 themselves but must react with other compounds to form fine particulates.
Despite its minuscule size, the EPA says PM2.5 is “one of the most dangerous forms of air pollution.” With a diameter roughly 30 times smaller than a human hair, these tiny bits of matter are small enough to bypass respiratory defenses in the nose and throat and embed deep in the lungs. Some may even slip into the bloodstream and harm vital organs like the heart and brain, the American Lung Association points out. More than that, PM2.5 may contain several harmful substances, including metals, chemicals, and potential carcinogens (cancer-causing compounds). Combined exposure to these pollutants can have many immediate and long-term health impacts.
Even if it’s just for a few hours, breathing tiny amounts of fine particles can present scores of severe symptoms and may even be fatal in some instances. According to a recent global study published in The Lancet Planetary Health, short-term PM2.5 exposure causes an estimated one million premature deaths annually.
An extensive body of scientific research has linked short-term exposures to particle pollution to a significant increase in:
Long-term exposure to PM2.5 can also be deadly, causing more than 8 million estimated deaths worldwide every year. It has also been linked to a myriad of health problems, including:
While particle pollution can occur naturally, it mainly derives from human activities. Most fine and ultra particles in the atmosphere are produced through chemical reactions from burning carbon-based fuels. Buses, cars, trucks, ships, trains, and other transport vehicles fueled by high-sulfur diesel and gasoline emit large quantities of PM2.5. Road wear of tires, brake pads, and other vehicle components adds to the problem, which is one reason why five of the top 10 most polluted U.S. cities are in California, the so-called “Capital of Car Culture.”
Several other significant sources of PM2.5 include trash burning, mining, construction sites, open agricultural burning, wildfires, and fossil fuel combustion at refineries, factories, and power plants. PM2.5 particulates may also originate indoors from combustion-related activities like cooking, smoking tobacco, burning candles, using unvented space heaters, and wood burning fireplaces or stoves. However, PM2.5 particles found indoors may enter through doors, windows, and “leakiness” in building structures.
Where humans aren’t the cause, PM2.5 can come from natural sources, including forest fires, dust storms, volcanic eruptions, decomposition of organic materials, sea salt, soil erosion, and biological particles like pollen and spores. In some cases, certain gases, such as sulfur dioxide and nitrogen oxides, may react with sunlight and water vapor in the atmosphere to form PM2.5. This is known as “secondary” PM2.5.
PM2.5 is harmful for anyone to breathe, but research shows that older adults with chronic heart or lung disease, children and infants, and asthmatics face the highest risk. Children and infants are particularly susceptible to harm from these pollutants because they inhale more air per pound of body weight than adults. Children also breathe faster, spend more time outdoors, and have smaller body sizes. Plus, their immune systems aren’t yet strong enough to combat PM2.5 like healthy adults.
The EPA has set a primary (health-based) annual PM2.5 standard at 9.0 micrograms per cubic meter (µg/m3), and a 24-hour average standard of 35 µg/m3. These rules are intended to “provide increased public health protection.” Still, according to a recent study in JAMA, “probably no safe level of exposure to PM2.5 exists—that is, the level below which no adverse health effects are observed.” With that in mind, you must limit your exposure to high PM2.5 concentrations as much as possible.
First, you’ll want to check your city’s Air Quality Index (AQI) to see current PM2.5 levels around you. If concentrations are high, restrict outdoor physical activity and shelter indoors.
If you must venture out on a particularly polluted day, wear a properly fitting respiratory protective device (like a mask or respirator) specifically designed to protect against PM2.5. According to one study, NIOSH-approved N95 respirators offer robust protection against PM2.5 air pollution by blocking up to 95% of fine particles down to 0.3 microns. And unlike regular face masks, respirators can achieve a very close facial fit to keep out airborne particles, the U.S. Food and Drug Administration (FDA) notes. For even greater protection, sensitive persons can consider using the N99 version of those respirators to filter more than 99% of airborne particles.
Everything from cooking to burning candles can release PM2.5 into your indoor atmosphere, so it’s good if your home or appliances have an extractor fan. You could also open a few windows to bring in fresh air and let out any PM2.5 pollutants that originated in your home. However, natural ventilation may not be the best option if the air outdoors is just as bad. Studies (like this one) show that installing a mechanical ventilation system can greatly reduce PM2.5 levels from within the home.
When indoors, where PM2.5 levels can be higher than outdoors, use an air purifier with a HEPA filter to eliminate fine particulates in the air. HEPA filters remove PM2.5 by physically trapping the tiny particles as air passes through their dense network of fibers. Specifically, HEPA filters can capture at least 99.97% of particles that are 0.3 microns in diameter, including PM2.5, since these particles are 2.5 microns or smaller.
Learn more: 7 Benefits of an Air Purifier for Your Health and Home | How Air Purifiers Help Reduce Allergies and Which One to Buy
Fine particulate pollution (PM2.5) is a serious and often invisible health threat affecting millions across the U.S. and around the world. Exposure to these particulates can increase your risk of heart disease, lung disorders, certain cancers, and even shorten your life expectancy. The good news? Simple, proactive steps like wearing a suitable face covering when outdoor air quality is poor and using a high-quality air purifier can help protect against these deadly pollutants. TruFlow Smart HEPA Air Purifiers are engineered to capture over 99% of harmful PM2.5 particles so you can breathe cleaner, safer air indoors.
Have questions or want to know which purifier is right for your space? Call TrustedAir today at (877) 869-1507 or message us. And don’t forget to check out our Air Quality Blog for expert tips and ways to reclaim your indoor air.
You can check current PM2.5 concentrations by viewing your local Air Quality Index (AQI) through trusted sources like AirNow.gov, the EPA’s AirData Air Quality Monitors interactive map, or air quality monitoring mobile apps. These tools provide real-time PM2.5 pollution levels and rate air quality from “Good” to “Hazardous.”
Yes, PM2.5 can cause environmental damage by reducing visibility (haze), acidifying lakes and rivers, harming vegetation, and corroding buildings and infrastructure.
Multiple independent studies using different methodologies found that PM2.5 particles that reach deep in lung tissue or enter the bloodstream are very difficult for the body to remove. Minimizing exposure to PM2.5 is crucial for protecting health and reducing the risk of severe illnesses.
Due to their ultrafine size and low settling rate, PM2.5 particles can remain airborne for days or weeks. This allows them to travel long distances and persist indoors and outdoors.
