VEVOR Luftqualitätsmonitor 9-IN-1 CO2 Temperatur Luftfeuchtigkeit Formaldehyd TVOC AQI Tester professioneller PM2.5 PM10 PM1.0 Partikelzähler für Innen/Außen Luftqualitätsmessgerät mit Alarmschwellen

Initially I received the monitor and liked it overall but the battery inside was bouncing around inside. I was concerned this would eventually damage the internal electronics. After communicating with the seller, they sent me a new one that had no issues. I offered to send back the old one, but they said I could keep it. I actually repaired the old one with some super glue after carefully opening it up. The nice thing about having two initially is that I could see how consistent both are sitting next to each other. Once they both reached room temperature, they readings were very close to each other. I also have a separate humidity and temperature device in the home, and again they were fairly accurate to each other.

CO2, Feinstaub und Temperatur funktionieren aber bei Formaldehyd und TVOC werden Fantasiewerte angezeigt. Hab mir mehr erwartet.

Important to note the reasons why this didn't get a higher rating: the stupid 'price-it-super-high-then-offer-huge-discount' model is beyond irritating. I rate it at the ETV of $96.57 (basically, that's what the seller claimed was actual retail value at the time I ordered it). That price is well above what this thing should be selling for, so, the current $119.99 price tag is pretty ridiculous. Offering a $50 coupon, at the moment, brings it to around seventy bucks, which is closer to reasonable and if they just listed it for that price, this thing would've gotten 5 stars. The only other issue is the built-in battery holds a charge that's enough to keep it going for around two days. It could just stay connected to the USB, but it's supposed to be cordless, and charging it creates heat, which causes a problem for the temperature function.Some pluses and minuses: the only things I'd say are a below optimal are the battery life and when it's connected to a USB-C charger, the ambient temp reading climbed quite a bit. From 72F to almost 80F degrees. So, be aware that while you're charging the monitor, it heats up and expect the reading to increase respectively. To the positive, the display is exceptional. The contrast is as good as it gets. The white digits against the black background, the size and boldness of the font, and the AQI graphics, all make this easily readable, day or night. The digits are over a half inch in height, so gauge this information to personal vision issues.The actual monitoring:The AQI seems to be quite reasonable, however a better test might be later in the Summer when we find our area experiences major issues with wildfires. Even indoor conditions are impacted... and even with air filtration. Currently, the AQI has been reading in the Good range, however, someone cooked up a meal last night and the meter actually jumped to yellow. The meter was 1 room and about 25' away. The measurements aren't numerical, just graphics showing from green, to yellow, to orange, to red, which is comprehensive enough for most people. It's quite good at picking up particulate airborne matter.CO2 works exceptionally well. The HUM (humidity) is extremely accurate, virtually identical readings to other devices we have. HCHO (formaldehyde), I have no way of comparing. TVOC (Total Volatile Organic Compounds) seem plausible, as there shouldn't currently be much in the air and the mg/m3 reading is jumping around at a low level of between .1 to .2. The PM2.5 and PM10 (particulate matter, 2.5 and 10 microns), again, I don't have a way to test for accuracy, however, these numbers all appear to be reacting in manners that correspond to the AQI and each other. When the unit isn't charging, the TEMP reading is quite accurate and actually reads in tenths of a degree.While navigating the settings is NOT intuitive, the manual is really well written, so setting the alarm defaults and the clock are simple tasks. There are only 3 buttons on the entire unit, +, -, and power, so knowing which button to long-press, or click twice to get into the mode you're seeking is best served by just reading the literature.So, the nutshell version, it's a nice enough unit, outside of the battery life. I feel the price range for this is around $50. It seems to perform well and it's a bit comical to now be able to show Chef Ptomaine how her cooking impacts the environment.

Update: After using this for awhile I can see how it could be very helpful. It lets me know when it’s a good idea to open windows, etc. I also noted that, just when heating something up briefly in my gas oven, the air quality got worse. Maybe there is something to be said about the dangers of gas ovens. I will be doing additional testing and research and making a few changes in my home, thanks to this eye opening tool. But, as hard as I tried, I can’t turn the warning alarm off. It did sound off the other day, which was a helpful alert, but I should be able to turn it off while I make adjustments to the atmosphere, without having to turn the machine off.Original review: This is lightweight plastic yet seems good quality. Easy to charge. I can’t tell if most of the readings are accurate since I have no basis in comparison. The only reading I can compare with other devices is the temperature, and the reading on this device seems pretty accurate. I wish a range of acceptable to unacceptable readings had been included in the instructions, as I’m new to this. I don’t like seeing the company’s logo and support information plastered on the front of the device. I find the settings buttons to be very off putting. There is supposedly a way to turn the CO2 alarm on and off, yet after trying numerous times, I really don’t see any way of telling if the alarm is on or off. In my opinion this is a good tool to have to give you a general idea of your air quality, though I can't verify if it is totally accurate.

Hope it lasts a while. Good product.

It measures PM1.0 - but no indicator of the resultsEverything else is greatBetter than Airthings which i originally bought and returned