It works well and has the features I wanted. Can't speak for the accuracy of data but it often disagrees with a walmart temp/humidity sensor... no idea which one is more correct.I would honestly give it five stars if the battery duration was longer and had better power management. For example, when connected you have to have the screen on continually so you can't do graph monitoring for long periods of time without the screen constantly shining on.Other than that is a good device. I wish I had some high accuracy equipment to use for calibration and verification of data, but it seems to work fine.

That's a dramatic statement but no truer words have ever been expressed. I will get to the specific point after a brief explanation. I am a retired senior and did not feel in great health lately, spending 99% of my time inside, at home.I've been having problems with my home for five years now. I've lived here for over 35 years and this has been a solid structure until recently.There has been a constant series of catastrophes for 5 years now. After renovations in a different section of the building, my house has shifted enough to cause a crack in the basement wall. In addition a section of my roof seems to have shifted and my power has occasionally cut off to my entire house.Lately I have been getting a smell of something like furnace oil fumes in my basement.My eyes were getting irritated shortly after getting up in the morning. A milky film formed over them that had to be constantly cleared to see properly. I also developed a feeling of nausea several times a day, losing my appetite.With everything combined, I was half expecting my home to tumble onto the street in a winter storm!Finally!!! I did some research to find an air quality monitor that wouldn't affect the grocery budget.It took a couple weeks to get use to the usual levels on the monitor and a few internet searches to see what each meant.I soon noticed that there was a reading of 10 to 15 times, over a 1000% increase in HCHO, formaldehyde level within a half hour. Still it remained within acceptable levels according to research.I eventually started a morning routine of opening the windows for a while.I also started to watch the HCHO levels suddenly increase several times randomly every day. Each time I opened the windows until it decreased again.Now I have almost no eye irritation or blurring and the nausea has completely disappeared. My daily feeling of well being and quality of life has improved significantly since I started monitoring air quality.I still haven't solved the mystery of suddenly increasing formaldehyde levels. I now have an idea what it is, and it's really Creepy.I'll keep monitoring by moving it to different rooms but I intend to buy at least 2 more of these so I have one for each of the 3 levels. Maybe each room eventually to help solve this terrible air quality mystery.I lastly found a huge leak in my roof maybe 4-6 ft long. I have a pull down set of stairs to access my attic so I can get up there easily. I finally had to get someone to repair my roof and was told a section of shingles had pulled apart from the roof next door. For now it's patched with cement until the spring or summer, when it will get a better look. Following that will be another serious conversation with the city about the renovation approvals process.Thank you very much for my continuing breaths of fresh air and a healthy appetite!Another save last night. I wasn't paying attention to open my windows as levels went up. Suddenly both HCHO and PM2.5 went up enough to set off the warning alarm. Thank goodness I got my windows open for a while before going to bed with such quickly increasing danger.

Update - it helped us find a problem. It reacts to off gassing and I'm grateful for finding it.It seems like it works but I am no expert. We tried it in the car on a 4 hour drive. It responded to changes such as a transport truck exhaust and opening windows. It is easy to interpret (if I am doing it right) bc it has a simple arrow that points to good. It doesn't seem to specify sewer gas detection but several different toxins are specified. Battery isn't super long.

Easy to use.Gives good infoSaved me from getting a pro to do it at a fraction of the price.

The PM 2.5 always reading as 7 ug, when you look at the pictures of the other reviewers, everybody's PM2.5 is 7, which means the PM2.5 doesn't work at all. On my unit, it always showing 7, and never change no matter what, even you blow the smoke to it, it still shows as 7.

Works perfectly

There are SO MANY choices for these air sensors, it's mind boggling and hard to decide.The last brand I tried was useless, ... the display was a fixed number, might as well have been a table decoration paper weight. Had to send it back.But THIS brand is Phenomenal!It checks for 5 types of substances, and has worked perfectly in my tests. The only one I haven't checked yet is formaldehyde, but considering how well it has performed in the other 4 tests, I suspect it will be satisfactory on that one also. UPDATED: I was able to check this 5th test factor and as expected it worked!The overall air quality gauge is a nice bonus as well!It should be noted that there is another review that has done extensive piecemeal tests on the 5 measurements this takes, and that some of them may be approximated due to the way this device is designed. This is good information, indicating that other sensors are available that are more accurate for specific testing, although in many cases this one should be useful for amateur purposes, and other sensors will likely be needed if used for professional purposes.For instance, I was able to to make it go out of range momentarily by exposing the device to fragrance infused hand sanitizer. I must say though, that I'd rather have a device like this which is sensitive and detects substances, than one which does not alert the user at all, and from what I've seen, it is very good with most specific substances as well. It even detected a large increase in particulate matter from smokey air that drifted though the neighborhood from forest fires several dozen miles away.I really love this unit! Here are the range of readings it gives me rather consistently when the air is normal:InsidePM2.5 = 7HCHO = .03TVOC = .06CO = 1CO2 = 600OutdoorsPM2.5 = 9HCHO = .02TVOC = ZEROCO = ZEROCO2 = 400

I purchased this model air quality monitor to test my home's air quality, specifically indoor air quality, humidity and temperature. It does work but readings compared to current simple device are 10 to 20 point higher. This leaves me with doubts about the accuracies of this product which is what I purchased it for.

I will not speak to or rate the accuracy of this device as I do not have a laboratory setup where I can compare the results to high-grade equipment.However, I will discuss the user interface and usability of the device. Some points:- The device will turn itself ON when a charging cable is connected to it, regardless of the position of the hardware "clicky" switch marked for On/Off operation. This tells me that the On/Off switch is more of a notion than an actual switch for power, kinda like the "power" button on your cell phone is not really a power on/off button.- There is a 199 second countdown when the unit is turned on where it states "Preheating" on the screen, and if any button is pushed during this time the internal voice announces "Warming up, please wait". This countdown/warm up sequence occurs at every start of the unit - regardless if you turn it off for 1 millisecond and turn it right back on, which tells me there is no "extra sensor" for telling the unit that it is "warmed up" and ready to run. It just assumes that the 199 seconds is what it takes to prepare its sensors for operation. This could have consequences that a failed sensor may give an errant reading without the unit doing any diagnostic to tell if the sensor is failed.- There is a - I guess you call it "mute" button on the device, except it doesn't mute much of anything. Even the directions say that it is a "Mute" button, and you should "Cycle to switch the sound on/off". If you press it, the speaker icon on the display goes dark, but the buttons still register a loud "BEEP!" when pressed. Also, when the "mute" button is pressed during the above mentioned "warm up" period, the speaker icon will dim, but any other button push will still have the voice state "Warming up, please wait". So much for the "mute" function, as I said it doesn't mute much of anything.- There is a setting in the "Settings" that allows you to turn off the mercilessly loud "BEEP!" with every button press. This setting does survive multiple sessions. Why the "mute" button above does not do the same thing is beyond me.- There is a setting that states "Display:" and has the choice of "Style 1" and "Style 2". Style 1 has "smoothed" numbers that look like they come from a standard, modern font. Style 2 has the numbers represented in an old 8-segment LED style, like old hand-held calculators in the 70's and 80's. Was this trip really necessary?- The user interface uses different colors to tell you if the reading value is - I guess - "safe", or more harmful. The documentation appears to reference the Chinese government values for each of the sensed values, so whatever the CCP had as its "safe" level at the time this thing was programmed is shown in green, then anything supposedly harmful will be shown in (progressively) yellow, then red, and finally purple. EXCEPT for CO and CO2 levels. Those are white all the time, no color changes in either "Style" or any value that I can get them to read, high or low.- There is a "Corrections" item in the settings that allows you to correct the readings (add more, or subtract some value from a reading) for HCHO, PM2.5, TVOC, Temperature, and Humidity. But not for CO or CO2. This may be due to what another review said that this unit does not really read CO or CO2, and simply infers these values from other sensor data like the PM and TVOC readings. The manual also does not state anything about "safe levels" or sensor ranges for either of these two carbon-based displayed values, but it does have that information for all the other sensors. Why would they display something they don't have a sensor for? If there are actually CO and CO2 sensors in the unit, why can we not A) calibrate them, or B) have them change colors for "safeness" like the other values do? I do believe that the CCP Ministry of Environmental Protection are busy-body enough one-upping the rest of the world to show they are "better than everyone else", that there are probably multiple places you can find their recommendations for "safe" and "dangerous" level specifications for these gasses.All in all, this appears to be the cheapest working-at-first-glance sensor of this type on AMZ at the time of this review. I know that companies engineer these devices to a price point, but some of the cost-cutting may affect performance, and in the long run maybe someones health. If you depend on this unit for your health, IMHO consult a doctor first.

Like - It is accurate. When my wife used her hair spray it recognizing it immediately.Dislike - It has a speaker, but no volume nob. Can't understand as it is very low volume

Very good device. I test it and It gives good information about air quality! Good price.Requares a lot of testing and pacience!

I am changing my review because this monitor didn't last very long. I purchased it in March and in November it was already broken. Nothing worked to reset it. I even let the battery go to zero and did many reset. The formaldehyde went into four red zeros and stays in it. I need that part to work in my house and it doesn't. I can't tell if the rest works because I have nothing to compare. The numbers are moving but somehow not to the level like they did in the summer. Even with a woodstove and smoke coming close to the monitor with the smoke alarm going off, the numbers are too low.I think the monitor doesn't work properly anymore.I tried to contact the company but I can't get hold of the company that is selling the monitor. I am still waiting to hear back from Bosean. I wrote twice to them and ask for help. So far, nothing.Right now, I am upset about not being able to get a proper answer or connect with any company to talk to.I hope someone from this company is reading this and will get back to me.

Be aware there is a preconditioning cycle every time you plug it in, or turn it on. This is normal.There is no calibration certificate of any type.Out of the box, in outside fresh air it indicated serious conditions, which was not the case. High TVOC, AND high CO2. There is a feature to recalibrate TVOC, in fresh air, and this improved the reading to low outdoors, and reasonable inside. Testing the second day indicated the CO2 in a closer to expected range. 480 outside 950 inside, I can accept this as useable.When set to off and plugged into charge, it turns on and stays that way until cord removed, likely increasing charge time. If you are planning to use it as soon as charged enough, switch it on before unplugging and it will not go through preconditioning again.Tried to run an 8 hour trend but battery did not last, would need to be plugged in for that. Cord is short but standard, so you can get a longer one if needed.