PM2.5 vs. PM10: Understanding the Similar Readings and How It Affects Indoor Air Quality Monitoring

Particulate matter (PM) is a major air pollutant that poses serious risks to human health. It is categorized based on size, with PM2.5 and PM10 being the most commonly measured fractions. However, it is not uncommon to observe the same readings for PM2.5 and PM10, particularly in indoor environments. In this comprehensive blog post, we will delve into the reasons behind this phenomenon and explore its implications for indoor air quality (IAQ) within commercial buildings.

Understanding PM2.5 and PM10

To comprehend why PM2.5 and PM10 can exhibit identical readings, it is essential to grasp their definitions and distinctions. PM2.5 refers to particulate matter that is 2.5 microns or smaller in diameter, while PM10 encompasses particles that are 10 microns or smaller. These particles can originate from a variety of sources, both natural and human-made. Common contributors to PM2.5 and PM10 include outdoor air pollution (e.g., car exhaust, industrial emissions, and wildfires), indoor air pollution (e.g., tobacco smoke, cooking and heating appliances, and building materials), dust and soil particles (from unpaved roads, construction sites, etc.), as well as natural sources like pollen, mold spores, and sea salt.

The size and composition of PM2.5 and PM10 particles determine their respective health effects. PM2.5 particles, due to their smaller size, have the ability to penetrate deeply into the lungs and potentially enter the bloodstream, leading to respiratory and cardiovascular problems. On the other hand, PM10 particles are less likely to penetrate as deeply and tend to cause irritation in the eyes, nose, and throat.

Why PM2.5 and PM10 Can Display the Same Readings

Air quality monitors measure the concentration of particles within a specific size range or fraction. While PM2.5 and PM10 particles differ in size, it is not unusual for both fractions to exhibit the same mass concentration in certain indoor environments.

This occurrence can be attributed to the counting methodology employed by air quality monitors. Rather than measuring the mass or weight of particles, these monitors count the number of particles within a given size range. Consequently, if the air solely contains PM2.5 particles and lacks larger particles, the readings for PM2.5 and PM10 would be identical. In other words, when there are no particles larger than 2.5 microns present for the monitor to count, it will indicate the same value for both PM2.5 and PM10.

This situation often arises in commercial indoor spaces, particularly when HVAC systems are equipped with filters designed to effectively capture PM10 and larger particles. However, these filters may not be specifically designed to capture PM2.5 particles. Therefore, even if the concentration of PM2.5 particles is high, the readings for both PM2.5 and PM10 can still appear the same.

To effectively capture PM2.5 particles in commercial indoor spaces, it is necessary to employ high-efficiency filtration systems such as filters with a high Minimum Efficiency Reporting Value (MERV) or High-Efficiency Particulate Air (HEPA) filters.

Implications for Commercial Indoor Air Quality Monitoring

Complications can arise in a large commercial facility when PM2.5 or PM10 particle data is misread or misinterpreted. This can lead to significant challenges and consequences. One complication is the inadequate response to air quality issues, where misreading or underestimating the data can result in delayed action or a false sense of security, potentially exposing occupants to health risks. On the other hand, overestimating the particle levels may lead to unnecessary panic and costly control measures. Non-compliance with air quality regulations is another concern, as misinterpreting the data can lead to unintentional violations, legal risks, and harm to occupants’ health. Additionally, misallocation of resources is a common problem, where inaccurate readings can result in ineffective resource allocation, such as investing in unnecessary filtration systems or neglecting appropriate control measures.

To mitigate these complications, accurate monitoring, calibration, and proper interpretation of PM2.5 and PM10 particle data are crucial. Regular calibration of monitoring equipment helps maintain accuracy, reducing the risk of misinterpretation. Staff training and education on understanding and responding to particle data are also vital. By prioritizing accurate interpretation and response to particle data, commercial facilities can effectively manage indoor air quality, ensuring the health and well-being of occupants while optimizing operational efficiency.

If you feel that your building or facility may need upgrades to the quality of your indoor air, make sure to contact us today to learn how AIRBOX can help.

Online Sales