What is PM2.5 and How to Reduce It?

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What is PM2.5 and How to Reduce It

Indoor air quality is more important today than ever before. There are also more options for homeowners to consider when it comes to air purification, with many masks and machines promising to reduce PM2.5 in the air. If you’re wondering what the term means and if PM2.5 is important, our guide has all of the answers you’ve been searching for.

Particle Pollution Explained

If you’re concerned about the air quality in your home, there’s a good chance you’ve heard the term PM2.5. The easiest way to explain this measurement is to break it down into two parts. PM stands for particulate matter, and the number that follows lets you know the size of the particulates in question.

Particulate matter is a mixture of microscopic solid and liquid matter that floats through the air outside and indoors. Sometimes known as Particle Pollution, these nasty little particles are not something you want to breathe and can come from a variety of common and unexpected sources.

There are two main types of particulate matter to be aware of as well, with PM10 and the aforementioned PM2.5. Any inhalable coarse particle designated as PM10 is 10 micrometers in diameter or smaller and can include common household allergens like dust mold and cigarette smoke. PM2.5, on the other hand, is significantly smaller. 

The EPA in the United States and other regulatory bodies worldwide monitor these levels and make changes to their policies based on the data. In the United States, the EPA initially set levels in 1971 and has issued a revision every decade. The last was in 2012 when the EPA revised their standards on PM2.5 to 35 µg/m3 during short term exposure in a 24 hour period while the annual standard is currently set at 12µg/m3.

PM2.5 Particulates

Ultrafine particles that are 2.5 micrometers in diameter or smaller are classified as PM2.5. They are invisible to the naked eye and around 30 times smaller than a human hair, which means they are hard to trap or remove. While PM10 particulates like pollen or dust can cause irritations in the respiratory tract, breathing in PM2.5 particles raises the probability of problems and poses a larger threat.

The Dangers of PM2.5

Ultrafine PM2.5 particles are small enough to travel deep into your lungs and could potentially enter your bloodstream. Exposure to these particles can cause various problems, including a decrease in lung function over time and an increase in respiratory problems like asthma. It can also result in an irregular heartbeat or nonfatal heart attack.

If you already suffer from heart or lung disease, exposure to PM2.5 can be fatal, so it’s not something to take lightly. It is especially hard on older adults, children, and people with preexisting conditions. While PM2.5 is something many people experience from outdoor pollution, it can also be a problem indoors with certain appliances and activities.

How to Reduce PM2.5

As you can see, keeping the PM2.5 levels low is important, whether you have an underlying condition or are in perfect health. While there’s only so much you can do to keep the particles out of your airways outdoors, reducing PM2.5 indoors is relatively simple.

Reducing PM2.5 Indoors

PM2.5 particles can enter a home anytime you open a door or window. Given their size, they don’t need much space to find their way into a room, but you can also generate PM2.5 inside your home through certain activities.

Anything that is burned indoors has the potential to produce PM2.5. That includes candles, wood-burning fireplaces, and space heaters that rely on kerosene. Do you smoke or have smokers in your home? That’s another source of PM2.5, but even self-cleaning ovens and cooking food can produce trace amounts of this particulate.

Just how much you’ll encounter from certain activities varies and may come down to the method of heat or the ingredients you cook with. No matter the process, having proper ventilation in the kitchen can alleviate your fears of PM2.5 in that room. The easiest way to do that is with a good range hood that’s vented to the outdoors.

When burning incense or any other substance indoors, always remember ventilation. Turn on fans and crack windows to let those harmful particulates out and fresh air in. If you happen to live in an area where the outdoor air quality is poor, you may want to keep those windows shut and limit any PM2.5 producing activities indoors.

Another way to lower the PM2.5 concentration in a specific room of your home is to follow our tips and invest in a high-quality air purifier. Not just any model will do, however, as it needs to be designed to combat small particulates like PM10 and PM2.5.

Can I test the PM levels indoors?

There was a time when homeowners would need to call in a specialist to check those levels, but technology has opened the door to handheld and desktop sensors for the home. Systems like the Air Quality Monitor from YVELINES can detect PM2.5 and PM10 in real-time along with TVOCs.

Reducing PM2.5 Exposure Outdoors

If you cook, burn candles, or perform any of the activities we outlined without proper ventilation, there’s a good chance you’ll have PM2.5 indoors. It’s far more prevalent outdoors, however, and those particulates can be carried on the breeze from hundreds of miles away.

The best way to limit or reduce PM2.5 exposure outdoors is first to understand where it comes from. Vehicle exhaust is a major factor in air pollution and adds PM2.5 to the atmosphere, but so do forest fires and volcanic eruptions. Those may not be a problem in some areas of the United States, but emissions from cars, trucks, busses, and trains are something none of us can completely escape.  

City dwellers may have already experienced PM2.5 in the form of smog, which is a visible indicator the conditions outside are poor. The best way to know the air quality before you head out for the day is to check the EPA's Air Quality Index. Simply typing in your zip code will bring up a report for your area and let you know how bad the PM2.5 and other irritants are outdoors.  

When the PM2.5 levels outdoors are in the hazardous range on the AQI scale, and you still have to go outdoors, traditional filtration methods won’t work. Dust masks may be cheap and popular, but they are essentially useless against ultrafine particles. Gaiters, bandanas, and other “regular” types of face masks are also ineffective, even with a filter in place.

There are only two types of masks that can combat PM2.5 outdoors with N95 and P100 respirators. With the rise of Covid-19, the N95 masks have become incredibly popular as they are certified by the CDC, OSHA, and NIOSH to filter out at least 95% of airborne particulates. That said, they are not resistant to oil, and neither are higher rated N99 or N100 filters.

When you want the best protection, you’ll want to consider a P100 respirator. While R95, P95, and P99 filters are all resistant to oil, the P100 provides 99.97% protection against airborne particles. They can be challenging to find depending on your location, but the CDC has a list of NIOSH-approved P100 respirators that can help you narrow the field.

Any mask must be worn correctly, considering seals are a weak point that can allow airborne particulates in. Respirators are more expensive and can be uncomfortable to wear for long periods of time, but provide a better seal than disposable masks with elastic straps.


While symptoms from PM2.5 exposure could simply cause eye or throat irritation in some people, the effects can be deadly to others. Whether you spend more time indoors than out, this form of pollution should be taken seriously. If you want to remove PM10 particles from your home and freshen up the air, check out our list of the best air purifiers for dust.

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