BTMETER - Air Particulate Meter PM2.5 PM10 Monitor Meter BT-5800D Pro Particulate Matter Detector, Accuracy +/- 20% Tester for Air Quality Monitoring Indoor Outdoor w/Back Light

I've found this meter to be quite accurate. Used it to verify HEPA filter functioning, as well as ambient particulate load in a variety of locations, all of which checked out exactly as one would expect. I was quite surprised at how much running the stovetop (gas flame) was able to increase the particle load in the household. I guess combustion products can be a real issue after all (at least for asthmatics). The reading also accurately jumped outside due to mold and/or pollen exactly when allergies in our household started up. Compared to the cost of similar meters, this meter is very good value. The display looks a little cheap (old-school dot matrix type), but I guess they had to save money somewhere to offer it at this price. The included chargeable battery is a big plus. Also the time averaging can be done over a "run" of a variable user-specified duration, which is another big plus. The construction is solid/hefty with a thick rubbery shock-absorbing feel. Overall grade: A+.

I purchased mine in March 2025 to help with TVOC issues related to my furnace, and still use it now for formaldehyde detection and air particulate detection. While I don't have a pro-grade detector to compare this to, it seems to work fine relative to what I'd expect it to detect in specific situations. As I've read in other reviews, it started to crap out after 2 years so I have a while until I reach that point. One thing to note is that if it's been turned off for a while, once you turn it on and TVOC levels finally start showing, it seems to start maxed out at 5.0 mg/m^3 and slowly decrease to where the TVOC level actually is. If you see this, don't be alarmed! Just give it a few minutes, and assuming the TVOC in your air is good, it will slowly fall back to 0.05 mg/m^3 which appears to be its minimum value.

I love this. It is so very helpful during the horrible northwest fire season. After too many years of living with intense smoke during the fire season and after spending some sizeable amount of money on a couple of good air cleaners....I thought I would check to see how well they are working or not with this device. As it turns out when the outside air is showing an aqi in the high 600's which is extremely hazardous to be in for any length of time. When the air cleaners are on the air is safe inside. If I test the air quality in a room that is closed off without access to the air cleaner there is a noticeable difference that the meter accurately measures. I am very confident of this device to a close accuracy. It will show better accuracy of the outside air where I live then what is reported in the farther away cities. 7.24.24 update After my initial excitement as written above, sadly this product turned out not so good after all. Last year we luckily didn't have much of a smoke season, so I didn't really use it, but once or twice. It didn't seem accurate at the time. Now with smoke coming in furiously I tried it again. It is clearly no longer accurate. I expected this to work longer than a year. Very disappointing !

It seems to be very accurate. It correlates well with the sensor in my home filtering system readings. Also quick readings and startup.

I've used mine a handful of times then I saw it giving me super high particle counts. It was obviously wrong so I opened it up and found that the small fan had stopped spinning. Its just 2 years old and not used much so in the trash it goes. Edit: and I forgot to mention that the battery was not charging so it was plugged in.