Brief background: I am a physician living in a very polluted city, study the effects of industrial and traffic related air pollution since 1995, test different air purifiers, filters and air quality monitors, have PURCHASED most of my equipment from Amazon and publish some webpages about air pollution. I am very sensitive to air pollution and usually detect spikes several minutes before good sensors detect them.Updated on 2016/07/03. I rated it as an Air Quality Monitor, not as an Environment Monitor, but it could work for both.I have two Awairs and will be updating this review because I think they are updating the software. This is an excellent device with excellent customers support, reflects quality but has a very important flaw with the humidity sensor and a shortcome with VOCs measurement.It does not work as an Environment Monitor yet (it should) because the humidity data is not consistent with AQI and another humidity sensor, taking into account that AQI is outdoors and Awair is indoors . But it is an excellent air quality monitor with two limitations. Let's see why:Humidity: it was +17% below actual humidity. Now it is +/- 11% below actual. I compare it with another humidity sensor and with my local AQI reports several times a day.Temperature: It had problems during the first week but it seems ok now. I verify it every day with two digital thermometers and an analogic one used to develop slides film and it seems awair is almost accurate but it does not show decimals.CO2 measurement with a real sensor for CO2. Very useful. It tells you when to open doors and windows to let fresh air in. It works great.VOCs metering: It does not use units but a VOCs index. I have two excellent VOCs sensors to compare with: My nose and symptoms, and the one that comes with my Winix 9500. Whenever my nose tells me there is important VOCs pollution, my Winix 9500 shows it with yellow and red bars. Definitely, awair is very sensitive. Just consider index 2 as polluted. Keep in mind that index 2 when dealing with benzene, formaldehide, etc., is harmful, but when dealing with your girlfriend's perfum is safe ... supposedly ;)PM2.5/PM10. It shows them as micrograms per cubic meter but does not differentiate PM2.5 from PM10 so, it really measures PM10 which means particles equal or smaller than PM10. I compare it with my Dylos Pro EMI and think Awair is reliable enough to get an idea of PM pollution.Score: unreliable yet. It takes into account humidity that comes with up to 17.3% error, CO2 that works well, VOCs with no units and PM that works well but you cannot compute a VOCs relative index with quantity values. Besides, temperature and humidity have nothing to do directly with air quality and both are relative: 65% humidity might be too dry for someone living in the jungle and 60 Fahrenheit might be too hot for someone living in Yellowknife, Alaska.Hopefully they can fix that all with software updates.Wifi: No problem at all but I use good routers. It just allows 2.4 GHz band but that is ok. The devices disconnect from the server, as far as I have seen because of the server - maybe updates, maintenance, etc. and they start working again with no problems, unless you try to fix it :) Anyway that is normal and they are live more time than AQI. If you change your wifi network, you must reset awair twice and must use bluetooth to find your awair again.It uses an app for tablets and cellphones, so you can monitor any site as long as you have wifi connection. That is very useful.OS: IOS and Android. I use both with no problems but prefer IOS.Bluetooth: No problems. For those of you how find trouble pairing it with bluetooth remember: the hole is on the left. 69 and 96 are not the same when talking about math ;)As AQI reports do not include VOCs, awair will help you TONS because they can represent important risks for your health and contrary to PM, they are very difficult to control; closing windows is not enough and most air purifiers are almost useless for VOCs. That you'll learn with awair.The articles and tips you get from your subscription to awair are very interesting. Unfortunately the tips might not always be accurate because the score might not be accurate enough all the time. Anyway, if you take that into account, you can use them for your needsAs a whole, the awair is the best home air quality monitor, much more useful than air purifiers sensors, even more sensitive than the Winix 9500's VOCs sensor. But the Winix display is like a red light. You will not miss a warning.In time, updates will be included as part of the initial reviewUpdate: 2016/07/03The more I use it, the more I like it. It is like a new car: understeers or oversteers, too much gas, etc. OK, let's see:General reaction: there is a lag, sometimes 1 or 2 minutessensors:Dust (PM10) overreacts compared with my Dylos ProVOCs: excellent sensitivityCO2: excellent sensitivityHumidity: displays wrong values half of the timeTemperature: not very accurate. Just enough to get byScore: It works but takes into account temperature and humidity and it is not very accurateRed/green dot on the right. Yellow dot desirable! Please!Software:I insist it should have a function to remove humidity and temperature for the score calculationsGreat statistics, graphs, reports. I have used them to detect industrial pollution, post them to twitter and got newspapers interest.You can directly share your statistics by email, tweeter, facebook, etc.UPDATE: 2016-08-25customers support:I had a problem with a sensor and Kevin sent me a new awair overseas and a form to return the defective one. They are always willing to help.The knocking function for the clock is very functional if you have your awair close to you. The clock is accurate.The display with LEDs is simple, easy to read, learn and understand and very useful because you immediately "get to know your air". No need to use the App unless you want numbers, statistics, tips, change settings, etc.You can simultaneously use the app to check one or more Awairs even from different devices. You can connect as many devices as you want in any place, room, city, country, continent, as long as you have WiFi. This is a great advantage to keep an eye on air quality for your kids'rooms, shops, theaters, etc., You can also create a small air quality network for your home, business, city, country, etc Awair is not a scientific instrument, but certainly is very useful, reliable and easy to use.Statistics: Very useful and they are improving the software with nice and useful functions.Awair Card: Their tips to improve air quality are superb. They are scientific, interesting and well supported.Battery usage: relatively low: 2% - 6% at the mostCO2, VOCs and PM sensors are relatively very accurate. CO2 is consistent with environment. So are VOCs and PM. I wanted numbers for VOCs but they are no really needed because VOCs toxicity depends mostly of the VOCs: low concentrations can be harmful. PM: I compare it with my Dylos Pro EMI and can tell awair is reliable.The humidity sensors definitely are not reliable enough. Temperature is not very accurate either but it is enough to get by. AQI considers humidity and temperature but they are unnecessary for air quality. It does not really matter if you want to monitor air quality and for this purpose Awair is excellent. AQI does not include VOCs. Awair does, which is a lot better.The red/green LED is functional but I still miss a yellow intermediate LEDI am also using another very interesting and portable device that you might consider, too: Air Mentor that looks beautiful, girls love it but it is completely different from awair's. You cannot just go for one or the other, because you might get disappointed. It would be like comparing a Ford SUV with a Mini. Both are cool, but do not have the same functionalities.I am very, very happy with my 2 awairs and hopefully can have more units later. Awair slogan “Get to know your air”is completely valid. It works!Update: 2016/10/02Awair now displays ppb for VOCs which is very useful to verify your air purifiers for VOCs. Bad news for air purifiers manufacturers because contrary to PM cleaning, they do not really help much with VOCs. (I have not been able to test Aerocide yet, so I cannot tell if it does do the work). Awair is not a portable device but it is relatively easy to locate it over the air purifiers clean air outlets and check results.As you might have read, I am also using Air Mentor that is portable, am comparing both and prefer Awair. With Awair you can easily get an idea of what is wrong with your air. With Air Mentor you always must use the app because the colors just tell something is wrong but do not provide any idea of what is wrong. If you need a portable monitor go for Air Mentor. If you need functionality, go for awair. I recommend you have both, several awairs if you can afford them and one Air Mentor for portability. If you cannot afford both, go for Awair; otherwise you might end up blaming Air Mentor that is also a good device. The other not-professional air monitors that I have seen are not any competence.