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PM2.5 - Everything You Need To Know About PM2.5

We live in an age where taking greater care and consideration with everything that we consume is crucial to protecting our health and wellbeing. Exercising caution is not just reserved for the food and drinks we put into our bodies — it also extends to the air we breathe.

It can be difficult to control outdoor air pollutants from wildfires to car emissions, but there are ways to monitor and maintain healthy indoor air quality. Controlling your indoor air quality will protect your body from the illnesses and diseases attributed to airborne pollutants.

The human eye is skilled at identifying when food is rotten or water is unclean just by observing its appearance or smell. However, it can be more difficult to determine if the air we are breathing is safe or if it is concealing hidden dangers that we are readily inhaling into our lungs.

Some larger pollutants are easy to spot. For example, when it’s pollen season, the tell-tale pieces of “fluff” floating about in the air are hard to miss. Or the Canadian wildfires in June of 2023 that has left many in the Northeastern United States with overcast haze filled skies from the traveling smoke. 

Other suspended particles are harder to detect because they can be 25 to 100 times smaller than an average human hair. Although we cannot see it, a pollutant can travel into our respiratory tracts and deep into our lungs and bloodstreams. Once there, these Volatile Organic Compounds (VOCs) can cause irreparable harm.


What Are Volatile Organic Compounds?

Volatile Organic Compounds or VOCs are compounds with high vapor pressure and low water solubility characteristics. Some examples of VOCs include benzene, ethylene glycol, formaldehyde, methylene chloride, tetrachloroethylene, and toluene.

Many household products contain VOCs including disinfectants, personal hygiene products, and home improvement items like paint and new furniture. VOCs react with other gases to form air pollution and can affect indoor and outdoor air quality.


What Is PM2.5 Pollution?

When rating air pollution for the Air Quality Index, the U.S. Environmental Protection Agency (EPA) uses a ranking system based on the diameter of airborne particles known as particulate matter. So, what does PM2.5 stand for and how are pollutants classified with this rating? 

The meaning of PM2.5 describes pollutants not seen by the naked eye. The EPA defines PM2.5 levels as inhalable particles with diameters of 2.5 micrometers or smaller. Just how small are PM2.5 particles? To put it in perspective, let’s compare a PM2.5-rated pollutant with human hair. 

The size of a human hair is approximately 70 micrometers in diameter. This means one strand of hair is 30 times larger than the largest fine particulate matter. Because they’re so minuscule, it's no wonder we can’t tell when we are breathing in harmful contaminants.


What Does PM2.5 Stand For?

If you're wondering, "What does PM2.5 mean?" we can help you sort through the scientific jargon. To start, PM is the abbreviation for Particulate Matter and the 2.5 designations signify the size of that particulate matter. 

Frequently used in scientific and technological fields, fine particulate matter is measured in microns. A micron is a unit of length that is equal to one-millionth of a meter and in the U.S., a micron is accepted to be 1/26,000 of an inch. This microscopic size is invisible to the human eye, which is why PM2.5 particles are considered so dangerous. 

When the particulate matter is 2.5 microns or less in diameter, it earns the PM2.5 rating. PM2.5 comes from a variety of emissions sources and has different chemical compositions. Some of the most common sources of PM2.5 particles are when gasoline, oil, diesel fuel, and wood are burned off (known as combustion). 

However, PM2.5 is not always man-made. Natural sources of airborne pollutants include trees and vegetation releasing secondary particles through chemical reactions of gases like sulfur dioxide and nitrogen oxides.

There is another particulate matter designation, PM10. It includes airborne pollutants that are 10 microns or less in diameter. PM10 is most frequently produced by agriculture, construction sites, industrial sources, and landfills. Wildfires — naturally occurring and man-made — also produce PM10 alongside PM2.5 particles, which is what makes wildfire smoke so dangerous.


Why We Need To Worry About PM2.5 Levels

No one is immune to the negative impact PM2.5 levels have on their health. While some people with pre-existing conditions like allergies, asthma, and heart disease are more prone to feeling these effects, there is no escaping the damage that breathing in PM2.5 particles can do. 

The PM2.5 health effects are both short-term and long-term. Some of the most immediate symptoms of exposure to PM2.5 pollutants include eye, nose, and throat irritation, coughing, sneezing, and shortness of breath.

People who live in areas where PM2.5 levels are considerably high can suffer permanent injury to their health and well-being. It is not unusual to develop asthma, chronic upper respiratory illnesses, and even heart disease when frequently exposed to PM2.5 air quality levels.


Why Are PM2.5 Particles So Dangerous? 

Because PM2.5 particles are so minute, they are able to reach the deepest levels of your lungs every time you breathe in air that is polluted with them.

The risk is especially great for those who choose to exercise outdoors when PM2.5 air quality levels are high, as they are inhaling more deeply than someone who is not exerting themselves while outdoors. 

PM2.5 levels affect more than just your lungs — they can also enter the bloodstream, where they eventually end up affecting every part of the body.

Your lungs and heart are most at risk for the ill effects of inhaling PM2.5 particles and repeat exposure can lead to heart and lung disease and increased risk for upper respiratory conditions and infections.





0 to 12.0

0 to 50 (Good)

Minimal risk


12.1 to 35.4

51 to 100 (Moderate)

At-risk individuals may experience respiratory issues.

Reduce prolonged periods of exertion. Exercise indoors only.

35.5 to 55.4

101 to 150 (Unhealthy for At-Risk Groups)

Increased likelihood for respiratory issues in at-risk people.

Heart and lung disease patients, children, and the elderly should avoid prolonged exertion.

55.5 to 150.4

151 to 200 (Unhealthy for Everyone)

Increased aggravation of heart or lung conditions in at-risk persons. Respiratory aggravation in the general population.

At-risk, children, and the elderly should avoid exertion. Everyone else should limit exertion.

150.5 to 250.4

201 to 300 (Very Unhealthy)

Significant aggravation of preexisting heart and lung conditions. Significant increase in respiratory aggravation in the general population.

At-risk persons should avoid all outdoor activities. All others should avoid prolonged exertion outdoors.

250.5 to 500.4

301 to 500 (Hazardous)

Serious aggravation of heart and lung conditions; increased aggravation for the general population; can lead to premature death in at-risk persons.

Everyone is advised to avoid outdoor exertion. At-risk individuals, children, and the elderly should stay inside.



What Is PM2.5 Air Quality?

The U.S. Environmental Protection Agency (EPA) has specific standards for PM2.5 pollution. The EPA defines PM2.5 air quality as PM2.5 levels above 500. Sometimes, the EPA notes, PM2.5 particles in the air exceed recommended levels and are labeled “beyond index.” 

When PM2.5 particles and other pollution levels exceed the EPA’s Air Quality Index (AQI) recommended levels, the agency suggests everyone take steps to protect themselves from the harmful PM2.5 health effects that can occur.

The EPA also warns that people who are most at risk of ill effects from hazardous levels of PM2.5 are those with heart or lung disease, children, and older adults.

Air quality conditions change rapidly and should be monitored for safety, especially for people who suffer from PM2.5 health effects like asthma or COPD.

The EPA posts AQI readings on a special website that helps individuals track what is happening with pollutants in their zip codes, cities, or states. 

Oransi also has a live map you can use to search for your area. You can use this tool to search for the live air quality and pollen count breakdown for your area. 

Using these tools is an effective way to help determine if you should take steps to reduce your exposure to PM2.5 particles or other airborne pollutants.


PM2.5 Standard Level

A normal or PM2.5 standard level is around 12 micrograms per cubic meter. The EPA revised the PM2.5 standard level in 2012 to help strengthen the air quality standards in the U.S. As part of the Clean Air Act, the EPA defined two types of outdoor air quality standards: primary and secondary. 

Primary outdoor air quality standards protect the public’s health from airborne pollutants. Secondary outdoor air quality standards protect the environment from the damage caused by pollution.

More than 300 epidemiological studies were reviewed as part of the EPA’s restructuring of the PM2.5 standard level. Those studies reported adverse health effects in areas with high levels of PM2.5 particles. Based on the data and other gathered resources, the EPA set both an annual and a 24-hour standard for PM2.5.


What Are The PM2.5 Health Effects?

PM2.5 health effects are numerous and serious, making it crucial for people to take evasive measures on days when the PM2.5 standard level is exceeded. Even short-term exposure to PM2.5 particles — defined as up to 24 hours — can shorten your lifespan. Immediate reactions can include difficulty breathing, upper respiratory infections, headaches, and eye, nose, and throat irritation.

The EPA defines who is considered most at risk from PM2.5 health effects. Children are the most at-risk group for adverse health reactions to PM2.5 particles because their lungs and bronchial airways are still developing.

Children also tend to spend more time outdoors than adults, meaning they have a greater opportunity to breathe in harmful particulate matter. Older adults and pregnant women should also take caution on days when PM2.5 pollutants are high.

Another group at high risk of experiencing PM2.5 health effects are individuals with preexisting heart and lung disease. This includes asthma and chronic obstructive pulmonary disease (COPD). If you are unsure whether the heart disease category applies to you, the EPA offers this advice. Heart disease, as per their definition for those who should avoid PM2.5 particles, includes:

  • Coronary artery disease
  • Ischemic heart disease
  • History of angina or heart attack
  • Stent placement
  • Heart by-pass surgery
  • Heart failure
  • History of stroke
  • Cerebrovascular disease
  • Peripheral vascular disease
  • Ventricular arrhythmia

What Kind Of Symptoms Can People With Preexisting Heart Or Lung Disease Experience If PM2.5 Particles Are Affecting Them? 

For those with lung disease — especially COPD — you will have difficulty breathing deeply. You also may notice that you are not breathing well, gasping a bit more than is normal for you. Coughing, chest pain, wheezing, and shortness of breath are all signs that PM2.5 pollution is aggravating your condition. 

People with heart or vascular disease may experience discomfort in their chests that include a feeling of fullness, pressure, or pain in the center of their chests that lasts for more than a few minutes.

Pain in other parts of the upper body is also common, along with shortness of breath, dizziness, and breaking out into a cold sweat. Heart and lung disease sufferers should not ignore these symptoms on high pollution days. Contact your doctor right away.

Individuals who are in an at-risk group should not wait until PM2.5 pollution levels are considered dangerous. Taking preemptive action — such as investing in air filtration units — is an effective way to safeguard your health.

In addition to using an air purifier, the EPA recommends keeping activity levels low (and indoors) and wearing a dust mask when you go outdoors. Using a good vacuum can also help remove particles that have settled on furniture and other household belongings.


Who Needs An Air Purifier For PM2.5 Pollutants?

While it is true that no one escapes the health effects of short-term or long-term exposure to PM2.5 particles, some people will benefit from using an air purifier indoors. Indoor air quality will be affected by what is going on outside your home. 

If you live in a city with a lot of traffic, the smog created from the vehicles’ exhaust can waft indoors. Wildfire smoke is becoming an increasing concern for everyone including most of the United States. Smoke that contains PM2.5 can easily seep indoors. Or maybe your job is near an industrial plant that releases harmful pollutants like cadmium, mercury, and other heavy metals.

The particulates from the air pollution the plant emits out can get onto your clothing and cling to your hair and skin. Then, you take those harmful contaminants into your home environment, where they continue to do damage to your health and that of your family. 

These are just two examples of why you might need an air purifier. Here are a few more:

  • Residents of cities with an Air Quality Index > 100 ppm. Regardless of whether you have a pre-existing respiratory condition, unhealthy PM2.5 pollution levels in your city can wreak havoc on your health. Air purifiers with HEPA filter based media can help keep your indoor air quality healthy and free of harmful particulates.
  • People who have asthma or other respiratory ailments. When you have asthma, your doctor likely recommends that you limit outdoor physical activity when air pollution levels are high. Using an air purifier to keep particulates to a minimum indoors is the best way to avoid the onset of symptoms while exercising.
  • People who have furry family members. Pets, especially dogs, require outdoor time to stay healthy. The problem is that fur can trap PM2.5 particles and other harmful airborne pollutants while your pet is outdoors. They then bring these particulates back inside your home, where they can affect your health. Air purifiers can rid your home of these pollutants without cutting into your pet’s outdoor fun time.
  • Pregnant women and babies are among the most vulnerable to PM2.5 health effects. We already know that high levels of air pollution can contribute to lower fertility rates in both men and women. It can also contribute to premature births. Pregnant women and mothers of newborns should protect their indoor air quality with an air purifier suited to their space.

How To Find The Perfect Air Purifier For PM2.5 Particles

We already know that PM2.5 affects air quality both indoors and outdoors and that one of the most efficient ways of reducing indoor air pollutants is with an air purifier. Not only can air purifiers take care of dust and other airborne contaminants, but they can also handle PM2.5 particles when equipped with the right filter. Top-quality air purifiers are expensive but well worth the price to have clean indoor air that doesn’t put you at risk. 

Air purifiers with PM2.5 activated carbon filters are among some of the best options. A PM2.5 activated carbon filter works by trapping chemicals and organic matter. Among the pollutants that PM2.5 activated carbon filters can capture include formaldehyde and other Volatile Organic Compounds (VOCs).

HEPA filter based media is the gold standard for combating PM2.5 pollution particles. Made of synthetic fibers, these filters trap the smallest particles, including pollen, dust, dander, and particulate pollution like PM2.5. 

If noise is an issue and you want to run your air purifier 24 hours a day, choose one that promises a 50db or less noise level. Clogged filters not only prevent your air purifier from working properly, but they can also damage your air purifier’s motor if they become overly clogged. 

It’s more efficient and cost-effective to replace your filter regularly than to replace the entire air purifier due to lack of maintenance. Lastly, we strongly encourage choosing an air purifier manufacturer that is dedicated to reducing its own carbon footprint.


PM2.5 Vs. N95: What Is The Difference Between PM2.5 And N95?

Face masks are helpful in preventing the most severe PM2.5 health effects. They are especially useful for people with pre-existing heart and lung conditions who need to take extra caution on days when PM2.5 air quality levels are high.

There are two options for protecting yourself from PM2.5 particles while outdoors: PM2.5 rated filters and N95-rated filters. While both provide excellent protection against inhaling particulate matter on high-pollution days, they each have their own advantages and disadvantages.



N95 masks are rated to capture particulate matter that is 0.3 microns in size at greater than 95 percent.

This makes them a wise choice for outdoor use. N95 masks are rated for effective filtration of bacteria, dust, pollen grain, and viruses. Since N95 filters only trap 95 percent of particulate matter, 5 percent still has the potential to enter your lungs. 

The other downside to these masks is they are not oil-resistant, so they only provide protection against non-oil-based solid matter.

Some people also find N95 masks difficult to breathe through since they offer strict inhalation resistance. N95 masks are available online and heavily regulated by the U.S. government to ensure they meet EPA standards.



PM2.5 filters are disposable and insertable into any mask. They create an electrostatic barrier that traps microscopic particles that can get through most other face masks. Using a PM2.5 filter insert offers added protection against the smallest aerosolized particulate matter. 

When a filter is PM2.5-certified, it is guaranteed to block most airborne particles. 

Their superior PM2.5 particle blockage capabilities do not make them harder to breathe through. This may make them more appealing to those with pre-existing heart conditions and asthma as they offer less inhalation resistance than N95 masks. 

Most people wear PM2.5 insertable filters with cloth masks, but they can be worn under other types of masks. What makes these masks so effective is they contain a PM2.5 activated carbon filter with these two layers offering better protection.

Finding a tight-fitting mask is crucial to ensuring it works properly as loose-fitting PM2.5 filtered masks can allow particulate matter to seep through.

Can you get air purifiers with a PM2.5 filter? The short answer to this question is yes. PM2.5 activated carbon filters are available for use in most air purifiers. They can be used in conjunction with or as a replacement for an air purifier’s regular filter.

It is important to note that air purifiers with HEPA filter based media are effective at removing particles rated at PM2.5 levels. Another option is to check an air purifier’s MERV rating. The higher the MERV rating, the better it is at reducing airborne pollutants. Checking the CADR number is also a good indicator of air flow and filter performance. 


How Long Do PM2.5 Filters Last?

A PM2.5 filter is highly resilient and retains its effectiveness for years when stored under recommended conditions from the filter manufacturer. Because they are relatively small and flat, they are also easy to store. This makes them an affordable option for use with indoor air filtration units.

If you opt for an air purification system that uses a PM2.5 filter, you can expect to change it every 2 to 3 weeks for optimal performance. A PM2.5 filter is highly effective but can lose its potency over time and with heavy use.

Some parts of the country experience higher levels of particulate matter pollution regularly and so in these areas, it may be necessary to change your PM2.5 filter more frequently.