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What Is Pm2.5 And How Bad Is the Pollution

Air pollution has become a global concern, affecting the health of millions and the environment we live in. Among the various components of air pollution, PM2.5 stands out due to its significant impact on human health and the environment. This article delves into what PM2.5 is, its sources, effects, and how we can mitigate its impact.

What is PM2.5?

PM2.5 refers to particulate matter that is less than 2.5 micrometers in diameter, which is about 3% the diameter of a human hair. These fine particles can remain suspended in the air for longer periods and can be inhaled deeply into the lungs. Unlike larger particles like PM10, PM2.5 poses a greater health risk as it can bypass the nose and throat and penetrate deep into the lungs.

Comparing the size difference between fine beach sand, human hair, PM10, PM2.5Image from EPA

Size Classifications of Particulate Matter

PM10: Particles with a diameter of 10 micrometers or smaller. Often referred to as “coarse particles,” they include dust, pollen, and mold spores.

PM2.5: Particles with a diameter of 2.5 micrometers or smaller. These are “fine particles” and can be produced from different types of combustion, including motor vehicles, power plants, residential wood burning, wildfires, agricultural burning, and some industrial processes.

They can also form in the atmosphere from reactions of gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds.

PM1.0: Particles with a diameter of 1 micrometer or smaller. This is a less common categorization but is used in some research and air quality monitoring contexts.

Ultrafine Particles (UFPs): These are particles with a diameter of 0.1 micrometers (100 nanometers) or smaller. They can penetrate deep into the lungs and more readily enter the bloodstream.

Sources of PM2.5 

Natural sources of PM2.5 include wildfires, volcanic eruptions, and dust storms.

However, human activities contribute significantly to PM2.5 levels. These anthropogenic sources include vehicle emissions, industrial processes, power plants, and residential heating, as well as secondary emissions from atmospheric chemical reactions between primary gas-phase pollutant precursors. 

Health Impacts of PM2.5

Short-term exposure to PM2.5 can lead to respiratory issues, eye irritation, and fatigue. Long-term exposure can result in chronic respiratory diseases, heart diseases, lung cancer, and can even affect the brain, nerves, liver, or kidneys. Children, the elderly, and those with pre-existing health conditions are particularly vulnerable to PM2.5 exposure.

What level of PM 2.5 is unhealthy?

Most research suggests that PM2.5 concentrations at or below 12 μg/m3 are generally associated with good health and carry minimal to negligible exposure risks.

Good (0-12 µg/m³): PM2.5 levels in this range pose little or no risk to health.

Moderate (12.1-35.4 µg/m³): Air quality is acceptable; however, there may be a moderate health concern for a few people who are unusually sensitive to air pollution.

Unhealthy for Sensitive Groups (35.5-55.4 µg/m³): Members of sensitive groups (children, elderly, and people with respiratory or heart conditions) may experience health effects. The general public is less likely to be affected.

Unhealthy (55.5-150.4 µg/m³): Everyone may begin to experience health effects; especially members of sensitive groups may experience more serious health effects.

Very Unhealthy (150.5-250.4 µg/m³): Health alert: everyone may experience more serious health effects.

Hazardous (250.5 µg/m³ and above): Health warnings of emergency conditions. The entire population is more likely to be affected.

Impact of PM2.5 on Indoor Air Quality 

PM2.5 can negatively influence indoor air quality in several ways:


PM2.5 particles can infiltrate indoor spaces through windows, doors, and cracks in the building. Even with closed windows, small particles can find their way inside.


The quality of a building’s ventilation system plays a significant role in how good the indoor air quality you’ll have. A well-ventilated space can help remove PM2.5, while a poorly ventilated space may trap these particles.


The use of air filters in HVAC (Heating, Ventilation, and Air Conditioning) systems can help capture PM2.5 particles, improving indoor air quality. High-efficiency filters, including HEPA filters, are able to remove 99% of the particles with a size of 0.3 µm, particularly effective at capturing fine particles.

Ways to Reduce The Impact of PM2.5

There are still ways that can reduce the negative impact of PM2.5 on living and working space:

Properly Ventilate: Ensure adequate ventilation in indoor spaces, particularly in kitchens and areas where smoking or burning candles is common.

Use the Right Air Filters: Use a ventilation system that fits the requirements of your space. Consider using HEPA filters to reduce the concentration of fine particles indoors.

Minimize Indoor Sources: Reduce or eliminate indoor activities that produce PM2.5 particles, such as smoking indoors or using wood-burning appliances.

Regular Maintenance: Regularly maintain HVAC systems and air filters to ensure they effectively capture PM2.5 and other pollutants.

Air Filters That Can Help Remove PM2.5

CleanLink offers a wide range of air filters that are great for use in removing PM2.5 in closed spaces.

CleanLink's primary to medium efficiency pocket air filter

Pocket Filter: provides great filtration performance in HVAC systems with low initial airflow resistance.

CleanLink's mini pleat HEPA air filter

Mini-Pleat HEPA Filter: As a HEPA filter, it removes 99.99% of particles with a size of 0.3 microns.

CleanLink's pleated panel filter

Pleated Panel Filter: This panel filter features a high dust-holding capacity while maintaining sufficient airflow velocity.

HVAC Air Filter Media: We also provide filter media in different fiber materials for filter manufacturing or replacement.

More Thoughts

Understanding PM2.5 and its impacts is the first step towards creating a healthier future. While the challenges are significant, collective action and informed choices can help us mitigate the effects of this invisible pollutant.

If you have any concerns or questions regarding air filtration, CleanLink has an expert team to assist you with filtration solutions. Contact us for more information.


Nature.com -Source sector and fuel contributions to ambient PM2.5 and attributable mortality across multiple spatial scales.

EPA -Particulate Matter (PM) Basics.

National Center for Environmental Health -Particle Pollution


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