PM2.5 vs. PM10: Why They Sometimes Read the Same and What it Means for Commercial Indoor Air Quality

Learn about particulate matter in commercial indoor air and why PM2.5 and PM10 can sometimes have the same readings. Discover the implications for IAQ monitoring and how it can help protect health.

Particulate matter (PM) is a serious air pollutant that can have detrimental effects on human health. PM can be classified based on size, with PM2.5 and PM10 being the most commonly measured. However, it's not uncommon to see the same readings for PM2.5 and PM10, particularly indoors. In this blog post, we'll explore why this is the case and what it means for air quality inside your building.

 

Understanding PM2.5 and PM10

The first step in understanding why PM2.5 and PM10 can sometimes have the same readings is to understand what they are and how they differ. PM2.5 and PM10 refer to particulate matter in the air that is 2.5 microns or smaller and 10 microns or smaller, respectively. These particles can come from both natural and human-made sources. Here are some common sources of PM2.5 and PM10:

• Outdoor air pollution: PM2.5 and PM10 particles can come from a variety of outdoor sources, such as car exhaust, industrial emissions and wildfires.
• Indoor air pollution: Indoor sources of PM2.5 and PM10 can include tobacco smoke, cooking and heating appliances and building materials such as paints and adhesives.
• Dust and soil: Dust and soil particles can also contribute to the levels of PM2.5 and PM10 in the air. This can come from unpaved roads, construction sites and other sources.
• Natural sources: Natural sources of PM2.5 and PM10 include pollen, mold spores and sea salt.

When particles enter indoor spaces through doors or windows, they can then become trapped indoors and create a concentration high enough to register as a PM2.5 or PM10 reading. Even emissions from nearby smokestacks, unpaved roads and construction sites can be found inside commercial buildings.

PM2.5 and PM10 can have different health effects on people depending on their size and composition. PM2.5, for example, is small enough to penetrate deep into the lungs and even enter the bloodstream, potentially causing respiratory and cardiovascular problems. PM10, on the other hand, is less likely to penetrate as deeply and is more likely to cause irritation in the eyes, nose and throat.

 

Why PM2.5 and PM10 Can Have the Same Readings

Air quality monitors measure the concentration of particles within a given size range or fraction, and PM2.5 and PM10 particles are often found together in varying concentrations. But while PM2.5 and PM10 are different size fractions, it's not uncommon to see the mass concentration for both PM2.5 and PM10 in some indoor environments.

 
If the air contains only PM2.5 particles, it would be possible to see the same value for PM10 that you see for PM2.5. 

When a monitor measures the concentration of PM2.5 or PM10, it is actually counting the number of particles within that size range, rather than the mass or weight of the particles. Therefore, if the air contains only PM2.5 particles and there are no larger particles present, the PM2.5 and PM10 readings would be the same since there are no particles larger than 2.5 microns present to be counted.

This can happen in commercial indoor spaces when operating a HVAC system with filter. When it comes to air quality monitoring in commercial buildings, it's important to understand that typical air filtration systems are only effective in dealing with PM10 and larger particles. For PM2.5, high MERV or HEPA filtration is necessary to effectively capture these small particles.

 

Implications for Commercial Indoor Air Quality Monitoring

While seeing the same readings for PM2.5 and PM10 may not be cause for immediate alarm, it does suggest that there are particulate matter sources present in the air. This highlights the importance of comprehensive indoor air quality (IAQ) monitoring in commercial spaces.

In addition to detecting and identifying sources of PM, IAQ monitoring can help facility managers and building owners take steps to improve air quality and protect the health of occupants. This might include upgrading HVAC filters, improving ventilation and implementing source control measures to minimize the generation of particulate matter in the first place. By utilizing high-quality air filtration systems and monitoring devices that are capable of accurately measuring PM2.5 levels, building managers and HVAC professionals can help ensure a safe and healthy indoor environment for building occupants.

In commercial indoor spaces, air quality monitoring is essential for protecting the health of occupants and ensuring compliance with regulations. While seeing the same readings for PM2.5 and PM10 may not necessarily indicate a problem, it does suggest that particulate matter sources are present and should be addressed. By monitoring IAQ and taking steps to improve air quality, facility managers and building owners can create a safer and healthier indoor environment for everyone.

 

Air Quality Monitoring Instruments from TSI

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