CO2 Meter Air Quality Monitor Handheld CO2 Monitor 0~9999ppm Measurement Carbon Dioxide Temperature Humidity Detector NDIR Sensor Indoor Outdoor Air Quality Tester

Indispensable instrument in this time of pandemic to ensure that your environment is adequately ventilated. I’m glad I bought this; my tightly sealed house had a reading of 1600 PPM CO2 and this meter clearly shows when the windows have been opened long enough to bring CO2 down to a healthier level of 600 to 800 ppm.Buy this if you want to look like a contractor. It’s ginormous and yelliw but actually light weight, especially for the size. C02 reading comes up in 30 seconds after a countdown; initial indoor relative humidity indoors after unit is outdoors takes a while to stabilize maybe ten or 15 minutes.The toggle between air, wet bulb, and dew point temperature is nice; kind of wish it also showed heat index.Now the bad: Terrible human factors design; without the manual you’d never figure this thing out - fortunately the tiny manual explains it all pretty well. Don’t lose the manual. Buttons are excessively debounced to the point that sometimes a button press isn’t recognized. A RS232 interface??? Stone age technology and forget about using your phone to log data.Alarm initially set to 1000 PPM probably isn’t a good choice; if you take this to your local grocery store or neighborhood bar or school or workplace and make a measurement that’s above this strict limit you’ll freak everyone out. It’s easily changed (but don’t forget the manual)I would buy this again. It works well. I like it.

We've bought several of these over the years and they are workhorses. Alway work, battery lasts forever, accurate and consistent.

The button actions are rather obscure, but it seems to be measuring C02 well. Of course other than the outdoor fresh air value of 400, I have no way of knowing how accurate it actually is, but that was a given before buying it. At the very least it gives me relative values which are still useful.

Scary but educational - may make you open windows !!!!!

Like that it's handheld and comes with a case although case is really oversized for the device. Device easy to set up. But need to read the instruction manual since there are abbreviations not necessarily obvious. would be nice if it comes with calibrating salts. But it does come with batteries.

Since I just received it I can’t tell you too much about it. Other than it seems to work easy the directions seem to be well written and I’m looking forward to using it. I just need to find out what the normal indoor CO2 numbers are supposed to be since mine is reading 933 in my house and we open our windows every day. I will let you know.I was surprised that all the stores I.ve been in have been well under 700. Highest was 600. Target was the best and lowest.

If you want to know whether your are living/working in fresh or stale air, this is the perfect tool. It is not a cheap purchase, but quality is rarely cheap. I love mine and wish more people were cognizant of air quality (which makes a difference during cold/flu/air-borne pandemic season). Great item.

From the SPECIFICATION, the CO2 readings must be increased by 1.6% for each kPa below normal pressure (101.33 kPa).At an altitude of 1000 feet (above sea level) the pressure is 97.717 kPa so the readings must be multiplied by 1.0578101.33 – 97.717 = 3.6133.613 x 1.6 = 5.78The meter instructions say regularly calibrate it and they say it can be calibrated outside in well ventilated sunny weather. But, an accurate calibration outside probably isn’t possible.The meter instructions say it can be calibrated outside but it also says the CO2 concentration must be 400 ppm where the calibration occurs. The calibration instructions don’t mention that the calibration would need to be done at sea level and they don’t mention 400 ppm probably doesn’t occur at sea level in the northern hemisphere.If 400 ppm occurred at sea level and if the calibration was done at 1000 feet altitude, then an error of 5.78% would occur in the meter after the calibration.The lowest dry mole fraction of CO2 in the northern hemisphere may be at a remote location like Mauna Loa. 420.85 ppm CO2 was the Daily Average dry mole fraction at Mauna Loa February 24 2022. It can be 500 ppm in a city like New York. Mauna Loa is the only place I could find with daily CO2 measurements. The last time it was 400 ppm at Mauna Loa was around 2015.The dry mole fraction doesn’t vary with altitude but the concentration does vary with altitude (from “How we measure background CO2 levels on Mauna Loa”). So, the meter must be measuring the concentration since the readings must be adjusted if it isn’t used at sea level.