Over 14,000 PurpleAir Air Quality Monitors Tested Against FEM/FRM Monitors

Scientists are raising concerns about low-cost air quality monitors... 

While these residential air quality monitors allow anyone to access air quality data, they can also be unreliable. Substandard air quality monitors can produce misleading information, putting communities and families at risk of air pollution-related illnesses. Additionally, it can lead to inaccurate studies and theories on air quality.  

So, how can you find an affordable air quality monitor you can trust?  

An air quality study tested the accuracy of over 14,000 PurpleAir air quality monitors against professional-standard FEM/FRM methods. And we’re discussing all about it in this article.  

Air Quality Study in 2023 

One major concern about low-cost air quality monitors is the lack of air quality research on them. On top of that, there aren’t set standards to ensure these air quality monitors are dependable. As a result, it’s difficult to tell if an air quality monitor is as good as their advertising claims.  

However, there is one way to test their accuracy, which is to compare the air quality data with the data from Federal Equivalent Methods (FEMs) and Federal Reference Methods (FRMs). 

FEM and FRM methods are systems that collect and analyze fine particulate matter (PM2.5) and are used by governments and scientists. They have become the standard for PM2.5 air quality data.  

So, an air quality study by Lance Wallace and Tongke Zhao compared over 10,000 outdoor and 4,000 indoor PurpleAir air quality monitors with 260 professional-grade air quality monitors using FEM/FRM. Then, they measured the data from 0-200 km to see if distance impacts accuracy and studied it within a five-year timeframe.  

The Results of the Air Quality Study 

Using correlation and the coefficients of divergence formula, the air quality researchers quantified the difference between PurpleAir air quality monitors and FEM/FRM air quality monitors.   

On one hand, they found that the fine particulate matter (PM2.5) data from the PurpleAir’s outdoor air quality monitors matched FEM/FRM data. On the other hand, they discovered that indoor PurpleAir air quality monitors showed some differences compared to the FEM/FRM. 

They attribute this to the following:  

• FEM/FRM monitors are in highly polluted and populated areas, but this isn’t always true for PurpleAir indoor air quality monitors. As such, the PM2.5 concentrations in each location will differ.  
• FEM/FRM air quality monitors only measure outdoor air quality, so it doesn’t reflect indoor air quality data. Meanwhile, PurpleAir has air quality monitors that can be used indoors and outdoors. 
• Indoor activities can contribute to indoor air pollution. So, it stands to reason that its measurements will differ from outdoor air quality data.   

In short, the air quality researchers report that the differences between the data of the PurpleAir indoor air quality monitors and FEM/FRM monitors don’t indicate inaccuracy. Instead, it proves indoor and outdoor air quality aren’t always the same.  

What Does This Mean for PurpleAir Air Quality Monitors?  

Despite being a low-cost air quality monitor, this air quality study shows that PurpleAir air quality monitors are especially reliable devices. Even when compared to FEM/FRM monitors—the gold standard in air quality.  

As such, PurpleAir air quality monitors help fill data gaps, make air quality data more accessible, and provide more information on indoor air quality. Most of all, they can be one of the best air quality monitors for academics as they’re affordable and highly precise. 

Connect With PurpleAir  

At PurpleAir, there are tons of organizations and researchers around the world using our data—from Google to the US Environmental Protection Agency (EPA). We’re thrilled to see research like the one we analyzed above be used to help local neighborhoods, and we look forward to seeing more in the future.  

Are you a technology company or institution looking to work with PurpleAir?  

We’d love to connect and see how we can help you. Whether you’re interested in our air quality monitors or using our air quality data for your projects, feel free to reach out.