The Dylos DC1100 Pro Air Quality Monitor is what I’ve often used to test the effect of air purifiers. I’ve also used the it to test whether indoor air is safer than outdoor air.
What The DC1100 Measures
The particle counter gives readings for:
- The number of particles 2.5 microns (also called “micrometers”) and above
- The number of particles 0.5 microns and above
- Measurements are per 0.01 cubic foot
They’re available through Amazon for $261.
Is The Dylos Accurate?
Is it accurate? We tested the Dylos against official PM2.5 readings (and another test of the Dylos versus Met One BAM PM2.5 readings). In our tests, we compared how well it performed against two other popular models–the Laser Egg and the AirVisual. We also tested whether humidity affects its accuracy.
To convert to micrograms per cubic meter of PM2.5, I used the semi-official formula that an engineer from Dylos emailed me:
PM2.5 ug/m3 = (# 0.5 micron particles – # 2.5 micron particles)/100
In most situations, results are highly similar even if we ignore the 2.5 micron particles. That’s because the number of 2.5 micron particles is usually (but not always) a lot smaller than the number of 0.5 micron particles.
They also produce a non-pro version that detects down to 1 micron, rather than 0.5 microns. Does this reduced sensitivity make the readings less accurate or less useful? To get some data on the question, we ran a test of the accuracy of the 1 micron Dylos against official PM2.5 readings.
Bottom line: The Dylos is a sufficiently accurate air quality monitor for regular air-breathers to use. However, in head-to-head comparison tests, it scores worse than other models.
Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.