Introduction To Airborne Particulate Matter

What Is Particulate Matter? 

Particulate matter (PM), or particle pollution, is a mixture of solid particles and liquid droplets in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen by the naked eye. Others are so small that they can only be detected using an electron microscope. For regulatory purposes, particle size is defined by micrometer diameter or micron size.

What Is The Difference Between PM1, PM2.5, And PM10? 

• PM10: inhalable particles with diameters that are generally 10 microns (micrometers) and smaller. PM10 airborne particles are typically combustion particles, organic compounds, and metals.
• PM2.5: fine inhalable particles with diameters that are generally 2.5 microns (micrometers) and smaller. PM2.5 airborne particles are typically dust, pollen, and mold.
• PM1: extremely fine particles with diameters that are generally 1 micron (micrometers) and smaller in size. PM1 airborne particles are typically VOCs, ultra-fine contaminants, viruses, and bacteria.
  

What Are The Health Risks of Particulate Matter? 

Exposure to small particles less than 10 micrometers in diameter can affect both your lungs and your heart. Numerous scientific studies have linked particle pollution exposure to a variety of problems, including nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function, and increased respiratory symptoms such as irritation of the airways, coughing, or difficulty breathing. People with heart or lung diseases, children, and older adults are the most likely to be affected by particle pollution exposure.

What Are The Environmental Risks of Particulate Matter? 

Fine particles (PM2.5) affect not only human health but also cause environmental damage. They are the main cause of reduced visibility (haze) in the US, which affects treasured national parks and wilderness areas. Wind can carry particles over long distances and settle on ground or water, causing a wide range of environmental damages such as acidification of lakes and streams, nutrient imbalances in coastal waters and large river basins, depletion of nutrients in the soil, damage to sensitive forests and crops, and reduction in ecosystem diversity. PM can also stain and damage materials, including culturally important objects such as statues and monuments, with some effects related to acid rain.

How Do Particulate Matter Levels Affect Indoor Air Quality? 

• <12 μg/m3: Exposure to these levels of PM2.5 is considered healthy, with little to no risk from exposure.
• ≤35 μg/m3: Prolonged exposure to PM2.5 at these levels for a 24-hour period is considered unhealthy and can cause issues for people with existing breathing issues such as asthma.
• ≥50 μg/m3: Prolonged exposure to PM2.5 at these levels can lead to serious health issues and is considered dangerously unhealthy.
  

How Can I Reduce Particulate Matter Levels Indoors?

Maintaining good indoor air quality is critical to ensuring our indoor environments are healthy for building occupants. However, with high levels of particulate matter indoors, purifying the air and filtering out PM1, PM2.5, and PM10 particles can be challenging, as not one solution can tackle all types of particulate matter.

For high levels of PM2.5 and PM10, it is recommended to first improve building ventilation. Improved ventilation will allow indoor and outdoor air to exchange, reducing particulate matter concentrations. Ventilation is best achieved by opening windows, doors, and increasing HVAC system airflow and runtime. For improved air filtration with existing HVAC systems is best to upgrade filters to MERV 11 or MERV 13 for higher efficiency in capturing airborne particles 2.5 microns or larger.

For high levels of PM1, it is recommended to increase localized air filtration with air purifiers equipped with ultra-fine True HEPA filters. Portable air purifiers with True HEPA filters are rated to capture airborne particles as small as 0.3 microns, ensuring the system can reduce PM1. Air purifiers with high-CFM fans can also improve ventilation and increase air exchanges within indoor spaces without windows or proper HVAC air distribution.

What Standards or Guidelines Exist For Particulate Matter Levels? 

When it comes to commercial indoor environments, no official standards are established for PM1, PM2.5, or PM10. However, it's important to note that the EPA has set National Ambient Air Quality Standards (NAAQS) for PM 2.5 and PM 10 in outdoor environments. Per the EPA's guidelines, various organizations have established indoor air quality criteria for particulate matter levels in reference to the EPA's Air Quality Index (AQI).