U UNNI CO2 Monitor Carbon Dioxide Detector for Home, 3 Adjustable Volume for Alerts & 3 Adjustable Backlight, Photoacoustic Sensor for Temperature Humidity & Indoor Air Quality Monitor

I've been trying to improve the air quality in my office and wanted to have the details available at a glance, so chose this monitor. The monitor has a very clear display; I'm able to read it clearly across the room without effort. I was impressed by the quality of the manual, as often the devices have very poor instructions. The device is powered by USB and includes the charger with a good length of cord and built in stand, though I might switch to the wall mount. Overall, I was pretty impressed with the features and surprised with how high the CO2 levels were in my office. The built in alarm for the different levels was helpful, and I can easily set the thresholds through the buttons on the front; instructions were very clear. Looks like I need to get a vent fan to improve the quality; wouldn't have known before. The sensor appears to be very sensitive and updates frequently, so the realtime analysis gives me confidence of the results. Overall, very good functionality at a great price.

Well made, well laid out and accurate monitor. Easy to setup with alarms that you set. Indoor temperature and humidity are nice added features. The unit monitors CO2 levels which is carbon dioxide in the air, TVOC which is Total Volatile Organic Compounds in the air, PM2.5 fine particular matter in the Air, PM10 Inhalable Airborne Particles and PM1Ultra Fine Particulate Matter. Easy to read from across the room. The instructions all well written and easy to understand. Highly recommended.

I’ve been really impressed with this CO₂ Monitor Carbon Dioxide Detector. The readings are accurate and refresh quickly, which gives me a lot of peace of mind—especially with a new baby at home. The built-in temperature and humidity monitor is a huge bonus. It helps me keep the nursery at a comfortable and healthy level throughout the day, and the indoor air quality indicator makes it easy to catch issues before they become a problem. I also appreciate the 3 adjustable alert volumes and the 3-level backlight. They make the device flexible for both daytime use and quiet nighttime monitoring without disturbing the baby. Overall, this monitor is easy to use, reliable, and packed with practical features. Highly recommend it for anyone who wants to maintain a safe and healthy environment at home, especially for newborns.

The Unni carbon dioxide monitor UN0601 is small and light and seems very accurate. The display is clear and easy to read and can be dimmed or turned off. It comes with a USB cord that plugs in to any charger. Batteries can be used for memory or temporary testing, but are not necessary for the unit to function. To test the accuracy, I placed it outdoors and it was reading 401 ppm, which is normal carbon dioxide level in outdoor air. Indoor it was reading 568 ppm and it was going up when there were more people in the room and with some candles lit. The level went down to 489 ppm in the same room overnight when there were no people or lit candles. The monitor also has a thermometer and humidity function. I tested it side-by-side with a UNNI thermometer and it displayed the same temperature and humidity digits as the other unit, with only a fraction difference. The temperature can be set to Fahrenheit or Celsius. The monitor has an alarm feature that can be set if the CO2 level becomes too high. I tested by blowing on it and it went up to over 1000 ppm and a window symbol was lit on the display, indicating it is time to ventilate the room. This carbon dioxide monitor appears to work great and can be used in places where people gather, such as in schools, churches or similar, but also in your home. EDIT: This is a review of Unni Air Quality Monitor UN0602. There is a USB power cable and adapter included in the box along with instructions. When you first plug it in, there is a few minutes of count down before the display starts to show any values. The calendar and clock is easy to set and there is an option for 12 hour or 24 hour format, and daylight savings time. The unit monitors CO2 in the air, expressed in parts per million (ppm). The outdoor air is typically around 400 ppm for normal clean air. CO2 values over 1000 is too high and ventilation is needed. I tested the device side by side with an older same brand CO2 monitor UN0601 and found that the values were close, but not in agreement until after one week of testing. There was a 60-100 ppm difference in the values, sometimes the old unit was lower and the new unit higher, and sometimes it was the other way around. I tested both of them outdoors and noted the value was close to 400 ppm for each. The CO2 reading can be calibrated if it seems off. I did not calibrate it, since the outdoor reading seemed accurate. After a week the old and the new monitor were displaying the same CO2 values. The CO2 monitor is using a photo acoustic sensor. The unit also monitors the total Volatile Organic Compounds (TVOC) and is displayed with five different color indicators, green being the lowest and purple the highest level. The monitor was mostly green during testing, but would quickly go to purple within an hour when cooking. Just boiling a pot of pasta on an electric stove, caused the monitor to show a purple indicator even if it was in an other room. I am more interested in VOCs from paint, flooring, furniture etc. in the home, so this can be a little misleading. The particulate matter (PM) measures pollutants smaller than 1 microns (PM1) or fine, measured in micrograms per cubic meter, smaller than 2.5 microns (PM2.5), and smaller than 10 microns (PM10), or coarse. These smaller particles are invisible, like soot, viruses, smoke etc. and can cause asthma and other health issues. Values below 75 are generally considered safe. All three PM values were showing the same numbers during testing, from 0-5. The values seemed to go up at the same time when the TVOC value was going up. Both TVOC concentration value and the PM values are measured with laser detection. Not sure how accurate they are. The ambient temperature and humidity is also measured and displayed. These values seem accurate, since I compared them to several other devices. The Unni air quality monitor also has alert functions that can be set for CO2 and PM levels. The alerts can be turned on/off. The backlight on the display has two brightness levels and can be turned off by touching the upper part. This monitor can be useful after home renovations or when moving into new places with unknown materials. It can also be useful if living in areas with suspected high air pollution.

I’ve finally found the perfect monitor for my needs! As someone who can’t smell at all, I rely entirely on devices to alert me to potential dangers in the air. Recently, a technician worked on my hot water heater and accidentally left a small gas leak. I had no idea it was there—hours later, someone else came home, immediately noticed the smell, and identified the issue. That experience was a wake-up call. Now, with this air quality monitor on my desk, I can constantly see real-time readings and feel so much safer. The display is the ideal size, with clean, bright colors that make the information easy to read at a glance. It’s given me incredible peace of mind knowing I can visually monitor the air in my home. I highly recommend this unit—it could truly be a lifesaver.

The U UNNI air quality monitor setup was very simple. It’s USB powered, took a couple of minutes to initialize, and the clock and calendar were easy to set. The buttons are intuitive and it was usable right out of the box without needing to dig too far through the instructions. I initially placed it in our bedroom, which gets noticeably less airflow than the rest of our condo. The color display is large, bright, and very easy to read. There are three brightness settings, bright, dim, and off. For a dark bedroom, even the lower brightness setting is still a bit bright for sleeping, but the ability to shut the screen off entirely while it continues monitoring is nice. During the day, visibility is excellent from across the room. The frame is light plastic, not too sturdy, but the screen is well designed, and it sits neatly on a nightstand or desk. Wall mounting is technically possible, though the back design doesn’t make it especially convenient. I don’t have another meter to compare against, but the unit is factory calibrated according to the instructions and it seems to track fairly accurately. Indoors, it responds quickly to changes, which was very noticeable while cooking (we have a gas range). We don’t have a range hood and tend to keep windows closed in winter, and this meter made it very obvious how much CO2 can linger after cooking, even hours later. Opening a window or actively exhausting air causes the readings to drop as expected. Over a few days of use, it became clear that this is more of an awareness tool than a safety device. It flags elevated CO2 levels and suggests when ventilation might help, but it’s important to understand that it measures CO2, not carbon monoxide. It’s not a replacement for a CO detector, but rather a companion monitor that gives insight into general air quality. Seeing alerts in the 1000 to 1200 range may look alarming on the screen, but those levels are very common in closed apartments and are not inherently dangerous. If you’re prone to anxiety, this kind of real time feedback and sensitivity could lead to unnecessary panic. This type of monitor is likely more useful to people who suffer from severe allergies or have health conditions that are sensitive to air quality. Overall, it does exactly what it aims to do.

This is a review of the U UNNI carbon dioxide monitor. I have to give this product a one-star rating because the carbon dioxide reading is completely unreliable, due to excessive calibration drift. From my brief experience, I have concluded that this monitor needs to be calibrated daily. Update 12/11/2025: I've now had this CO2 monitor for over two months. During those two months, I've run many experiments, maintaining careful log readings. Two months of experiments confirmed my initial judgements: My monitor drifts low after calibration, making it unreliable. The calibration process involves taking the monitor outside, where the monitor sets itself to read 400 ppm in outside air. Of course, CO2 in outside air might vary between 350 ppm and 600 ppm, but the monitor will set itself to read 400 ppm no matter what. Whenever I would calibrate the instrument, the indication would rise 20% to 50% from its value prior to calibration. After calibration, the CO2 indication drifts slowly lower and lower as time passes, as much as 150 ppm to 250 ppm. Either outside air CO2 is changing by 150 ppm to 250 ppm between calibrations, or the monitor's calibration is drifting low. Calibration drift makes this CO2 monitor useless for our home. Pros: Very nice display. Cons: -- [Major] Not accurate. Carbon dioxide reading drifts significantly after calibration. -- [Moderate] Inconvenient calibration process. -- [Minor] Requires power input, but power supply is not included. -- [Minor] Inaccurate temperature indication. Unreliable accuracy: I have to give this carbon dioxide monitor a one-star rating because I cannot trust its accuracy. After unpacking the carbon dioxide monitor, I performed the calibration procedure per the user manual. After calibration, the monitor read 400 ppm while outside, confirming the calibration was successful. I moved the monitor inside and the reading was between 800 and 1000 ppm. By the next day, the reading had decreased to about 600 ppm. The following day (two days after calibration) the reading had decreased to 430 ppm. I then recalibrated the monitor (so it read 400 ppm in outdoor air). Moving it back inside, it read 650 ppm (220 ppm higher than immediately before calibration!). For the monitor to drift so far out of calibration in just two days makes this monitor completely unreliable and unusable. I may try to borrow a calibrated industrial carbon dioxide monitor to compare to this device immediately after calibration. Inconvenient calibration process: Some carbon dioxide monitors have a very simply calibration process. For example, some monitors might have you press a button three time in rapid succession. This monitor has a very inconvenient process. You must unplug the USB cable and batteries and take the monitor outside. While outside, you must continuously hold a button while you insert the three batteries. When you hear beeps, you leave the monitor for a few minutes until it finishes its calibration. Finally, you must remove all power again (remove the batteries), then restore power (reinstall the batteries or plug in the USB cable). This process is unnecessarily complicated! I especially hate having to hold a button down with one hand while inserting three batteries with the other hand. I also find it odd that users must remember to remove power and restore power to complete the calibration. Why couldn’t they just follow the example of others and press a one button three times? Or at least have the monitor automatically reset following calibration without requiring a power-off, power-on. Power supply not included: This monitor needs a power supply. It can operate only a very short time on batteries. The power is supplied via a USB C socket on the monitor. A USB A to USB C cable comes in the box. You must provide your own USB power source. If you want to move this monitor to different rooms in your home, you might need to buy a new USB power supply block, raising your total cost to use this monitor. Temperature reading is 2 degrees F too high compared to calibrated instrument.

This is a sophisticated air quality analysis system. It measures CO2, particulates, indoor temperature and time. It is very easy to set up. The manual is very clear with color pictures and well written instructions. It is interesting to see how air quality changes throughout the day. I recently received this device but I have others from the same company and they have worked beautifully over time. I anticipate using this air quality monitor for many years. It is so comprehensive in measuring air quality that it is a great value for the money.