TemtopSmart Air Quality Monitor - Indoor Air Quality Meter with PM2.5, AQI, Temperature, and Humidity Detector for Home, Office, or School, App Connectivity, 60-Day Battery Life

This is reasonably similar in accuracy to government level devices at reasonable levels.I'm writing this review in response to other reviews complaining about things they don't understand.First of all, if you actually read the specifications of the sensor, there is a reasonable margin of error. I've tested this sensor and there is actually a government website that compares Elitech's sensors to government sensors for PM 2.5. It is accurate and within the specified margin of error. Yes, even the same sensors side by side will be slightly different from each other. If you are complaining that it one shows 3 PPM and another shows 5 PPM, then you need to realize that at those levels the margin of error is 5... so being 2 points apart is within the specifications of sensor. And either way, it literallt makes no practical difference; you would still know the air is excellent. The same goes for if one reads 100 PPM and another reads 90, that is also within the margin of error and you would still know the air sucks!Second, there are multiple modes. If you put it on a mode where you make the sensor work every 1.5 seconds, of course the battery is going to be used up faster compared to if it runs every 5 minutes or every 30 minutes.Lastly, if you are complaining that the readings are completely different from each other or that the number doesn't change even if you move to different places... you probably have them refreshing every 5 or 30 minutes and you need to put it om the "R" mode where it refreshes every 1.5 seconds instead if you want instant information.Basically, all the negative reviews are by people who don't understand but think they understand. This device does what it is supposed to and is well engineered. People who complain literally can't read or didn't bother to read about what they were buying.

I was told by my pulmonologist to buy some hepa air purifiers for my allergies and asthma. While researching those I came across a review where the commenter mentioned she bought an AQI to test if the air purifier works well. Now I never heard of something like this existing - I thought you would have to hire a specialist to come out and test for things like this with expensive professional equipment. If I had known about an AQI before I would have bought one ages ago.I've seen a lot of criticism about the battery life, but there are actually 4 settings. When I first got the device I put it on the R setting (test every 2 seconds) and walked around each room of my apartment to see what the air quality actually is. This setting uses the most battery power and I don't like it because the numbers swing wildly and it's confusing. I tested out other settings as well and decided to keep it at A. While on A the AQI remains fairly stable. I recieved my device almost a week ago and the battery is at the halfway point.How do I know this device is accurate? The AQI remains mostly in the single digits, but when I light a cigarette the device can go as high as 80. I was shocked, I had no idea it was that bad. This gives me something to think about......One last thing - my car A.C. is running cool not cold like it should. I already took it back to the mechanic twice after paying 2k for a total rehaul. The mechanic insisted, on my 3rd visit, they tested the temp of air coming out of vents at 48 degrees. I knew this wasn't right at all because I'm sweating like crazy. One day I had to run errands in diff parts of town. I bright this monitor and put it on the console tray which is right above knee level. The kickstand included was so helpful! I drove to 4 places in 3 hours, about 60 miles altogether. After each stop i took a photo of the reading (please note AQI is higher in 2nd photo because I smoked with the window cracked). The interior temp of my car never went below 90 (live in Arizona) and I plan to take my evidence back to The mechanic to prove they didn't do it right the first 3 times. Thank your for creating such a useful device at a great price!

Works as it should. Very interesting to see how many pollutants are in the air. I was stories at all the natural cleaners i use that put it in the yellow or red.

This air quality monitor is legit. Before AQI 20. After blowing fresh air from an air purifier directly it came to 1 AQI.

I've used a Temtop P10 monitor for several years for monitoring the particle density while flying in areas where wildfire smoke is present. It's usually stratified, and a small altitude change is often enough to make a big difference -- and I've used it for monitoring inside particle density for sensitive individuals. I decided to try the new model S21, which is even less expensive than the P10, and I'm really impressed. The only thing it lacks is a backlight -- which extends the battery life from a few hours to several days, but it's very readable even in dim light. And its readings track the P10 (and nearby monitoring stations) closely. Wildfire smoke is sometimes pretty bad here, so I got a couple more S21s to give for Christmas presents.