UEi CO71A Handheld Digital Carbon Monoxide Detector - 0-999ppm Range CO Meter with Visual & Audible Alarms | Portable CO Monitor for Home Safety, Garage, RV & Workplace | Battery-Powered CO Tester

So I have been breathing in nasty stuff and no one would listen. I called poison control and they said "OMG that sounds you have CO exposure plus other toxic chemicals in smoke. You are probably sensitive to even low levels of CO".... Some one should give that man a new title Doctor! He was more educated them most of them. Not only will my CO spike above 30ppm and I feel incredible pain and nausea at only 9 ppm. Now that I have this I have a warning window of when the spike is going to come. This PROVED that nothing in my house was leaking CO. I tested it outside when the "burning" stared and sure enough high spikes. Came in and it was clear. Within 10 minuets my house was up to 25 ppm fluctuating area to area. I would not have this critical information as CO alarms dont even sound for a month! Look it up! THEY ARE TRASH for sensitive lungs and will only sound from as low as 35 but even then has to be STEADY at that level or higher for over an hour. I would already be in the ER if I wated that long to find out... I already have been. Since I bought this I can mediate and defend my home and health much better. I can not stress enough how important this device is now to my very life and existence. THANK YOU!Only issue was it came damaged. It only ever showed 00 when it should have been 000. Then the other numbers went wacky. I 10000% blame packaging by amazon shipping centers. It was in a giant box with a tiny bubble and very much so tossed around. The crack on the screen is now apparent.. BUT! its still reading accurate! I get my second one tomorrow and the broken one is going back nice and easy!This is a great little CO detector, however, it really doesn’t alert me like I would like. I purchased this to be a personal carbon monoxide detector as I am an HVAC technician, and am constantly entering homes, and dropping into crawl spaces and basements dealing with HVAC issues. The only thing it has on it for alarms is a small LED light on the top that flashes when it is above one part per million. There is no audible alert and no vibration. For the same price other personal detectors will vibrate and sound an alarm, which is much more valuable to me because when I’m busy I’m not staring at my carbon monoxide detector, I’m busy working. So this is a good little device, however I have gone with a personal detector that will properly alert me when I am in danger so I can take appropriate action.Although not certified for use in aircraft, I use it to check for carbon monoxide in my cabin on occasion. I bought this after my newly purchased used aircraft went into annual and was found to have significant erosion around an exhaust port requiring a cylinder replacement. With regard to this product, it is indeed very accurate. Your first "test" will probably be to stick it under a car exhaust to see if it alarms, which indeed it rapidly does! (Note you'll have to move it to clean air for about 30 minutes to de-monoxide it after the test. In my aircraft, on the ground in Houston (near many oil refineries) I noticed it would read between 2 and 5 parts per million (PPM) of carbon monoxide. Airborne and flying over Arkansas it would gradually start moving towards 0ppm so I'm confident it is working well. Again, although not certified for aviation use, it is certainly more accurate and timely than the useless "black dot" stick-on indicators that are slow to react at best and essentially useless if over 6 months old (leading to a false since of security?). Get one, you'll be glad you did! Oh, almost forgot - brought this to a friends newly-bought pre-owned house and checked the vents when the heater was running and detected about 125ppm of carbon monoxide. The HVAC fellow came out and found the furnace manifold cracked which is quite dangerous. My friend (and pregnant wife) were eternally (excuse the pun) thankful for me testing the vents. Get one, a little pricey but the alternative is much, much worse.I have only had this a relatively short time. I'm a retired, but still working air pollution chemist with training in industrial hygiene. I have access to much more expensive equipment to measure Carbon monoxide. I plan to check its calibration much more carefully but I thought I would share this quick review. I prepared a simple calibration standard by injecting a small measured amount of pure CO (4 ml) from a gas cylinder into a known volume of air (a small box 6.9 liters). It's concentration should have been about 580 ppm, and the monitor reported 572 ppm. For a first check I was very pleased given that this is a one point and quick calibration check. I will update on the calibration later. I then used the CO meter in a middle school demonstration for simulating burning carbon-based fuel (for the class I used a small piece of incense) in the atmosphere (represented by a small jar). I lit the incense, and placed it and the CO meter in the jar, along with a toy automobile to represent a source of carbon fuel combustion and covered the jar with it's lid. In a few minutes the CO meter, facing the students, increased quickly to a surprising high value (understand few people can burn and breath incense in a 2 quart jar. Anyway everyone had fun with this. I will follow with another review update in the next few weeksThough these things are pricey they are worth every penny. After much study on co I realized my kidde co detector is only helpful in sounding an alarm when it's over 30ppm . Should be 10ppm. These nice handheld models will take a reading down to 1 ppm. You'll know how much co your breathing. I installed a ventless fireplace and I wanted to know. It toggles between 0 and 1 ppm. The peace of mind is worth it.I work in boiler room and go into tenants apartments. And was originally going into multiple boiler rooms on weekends in different locations. Anything to detect CO is vv important. I was in class for work and the teachers recommended we carry one. Like I said when I go in tenants apartment they have stove on for heat and I want to live as long as possible. No alarms yet but you never know. Better be safe than dead!