A18 Air Quality Monitor Indoor Co2 Meter Dust PM2.5 PM1 PM10 Particle Counter HCHO Formaldehyde TVOC Detector AQI Pollution Tester Home with Data Record

I’ve had this meter for a few days and these are my impressions so far:Pros: Fit and finish are top notch. The display is attractive and easy to read. The operations menu is easy to navigate. Air measurements are continuous and the unit responds quickly to air quality changes. Historical measurements are easily viewed. The monitor may be kept plugged into a power source for longer term monitoring rather than being dependent on the internal battery’s charge level.Cons: The directions that come with the unit are somewhat vague, especially as it deals with calibration. Example - “The sensors may drift after prolonged use. User can place the monitor outdoor with clean air environment to recalibrate the sensor.” So how long is “prolonged”? How long must it be kept in “clean air environment” before calibration occurs? Is calibration automatic or does it need to be initialized using the menu system? This is just one example of several instances found in the operating manual.How accurate is the device? There is really no way to know with this or any other air quality measurement device unless you have the availability of a lab that can produce known gas concentrations to use to test these units against. I will say that it appears to be accurate. I base this on the values it displays when outdoors. I live in a rural area with what I feel is good outdoor air quality. When reading outdoor measurements after a thunderstorm, the HCHO and TVOC levels each measured <0.001 which is expected. CO2 measured 400 which is also what is expected.Indoors in a windows closed air-conditioned environment showed an elevated TVOC OF 3.6 (high) and a HCHO level of 0.065 (normal range). CO2 levels rise as expected with two adults and two medium-sized dogs. With the monitor placed in the bedroom, the overnight value rose to a value of 920 (elevated).As this is mid-July, opening the windows and running the attic fan to ventilate our home is limited to late evening and early morning hours. Doing so brings the values measured back to normal ranges rather quickly. As the outdoor temperature rises, requiring closing of windows and and turning on the A/C, all values begin to rise to pre-ventilation values.While the operation manual could be better, I feel that the air quality meter itself does a good job. It doesn’t have Bluetooth, WiFi or an app but it does have a quality build with what appears to be accurate and useful readings. Reading the specs in the description suggests that this company placed an emphasis on the quality of the components used for measurement rather than connectivity or apps. For these reasons and my experience thus far I’ve provided a rating of 5.**Update 05/06/24**This unit is still operating well. I've had no issues with it. I've been able to maintain a much healthier environment by opening a window slightly when HCHO, TVOC, or CO2 levels are elevated. The unit is very sensitive and reacts quickly to air quality changes. I'm very happy that I made this purchase.

We bought this to monitor our inside air quality. It was never very good - readings often seemed inaccurate - but the main problem is it just quit charging after a year and a half. For the price, I expected better.

Update, so I've been meaning to update my review and add a star as the reading calmed down and I've started to really trust them. In fact I was really impressed, but I unplugged it this week and it will not start back up. I've had it Just less than 1 year, about 1 week less and looking at it it would appear to be slightly swollen making it near impossible to remove the tf flash, and the power on button doesn't seem to move either now. I suspect the battery has expanded (not good!). I also do not know how long the warranty is good for either outside of the 30 day return window. Hopefully it will be replaced, I'll update again if it is.Co2 reading spot on !! PM2.5 is also very accurate.TVOC readings seem to be about 10x higher than my other sensors. Instead of reading between 0.200 and 0.300 this device is showing 2.xxx to 3.xxxx inside my house. Outside it shows near Zero. Re-calibrated a few times outside but once I bring the device inside the numbers race upwards.Also the device will randomly power down (done it twice so far), once when the battery was almost fully charged and shutdown when I plugged it back into a 5v source. The second time was when I was just watching the screen. I really wanted to like this, very few devices in this price range report test multiple PM sizes.

I really want to like this BRWISSEN A18. It looks great and is easy to operate. Most of the values displayed are typical and agree with my other monitors, within reason. It is also one of the more expensive of the 'inexpensive' air quality monitors.However, the TVOC value is EXTREMELY inaccurate, about 10 - 20 times higher that the value displayed by any other monitor.I have given it LOTS of fresh air and done all the calibration procedures in the manual, many times. Still the values being displayed suggest I should seal the room and never return.After some experimentation, and with some relatively simple configuration changes (outside the unit), I have been able to get reliable TVOC readings that are pretty close to the values displayed by other monitors. Good news, everyone, we get to stay in the office.Looks like there is either a manufacturing error or more likely a design flaw.Now I have to decide if I am going to apply changes inside the unit to make it work, but no doubt void the warranty. Or return it and hope the next one is better. Of course, if it is a design flaw, chances the next one is better are not good. So now I have to decide if it is worth a $200 lab experiment in the next couple weeks.

After a couple of months, I thought it broke because it would no longer charge. It turned out, however, that the usb connection was faulty. I took it apart and the electrical connections on the usb connector were not soldered onto the board. Maybe it was a manufacturing defect, or a shortcut. Either way, I've seen a lot of reviews with the same symptom. I soldered the electrical connections on the usb connect (difficult! very small) and it's been working for a couple of years now