Review on Digital Portable Temperature Humidity Analyzer by Mark Ponnusamy

First, it works very well. Very sensitive and responsive to changes in nearby CO2 levels. face coverings. Outdoors, the CO2 concentration in the ambient air was around 500 ppm. I held the monitor to my nose and took readings from 1500 to peak around 2800 ppm. With a simply sewn fabric mask. I keep the monitor in the same place. the reading reached 9,999 ppm in a minute or two. This is the limit of the counter. The CO2 level was over 10,000ppm, I have no idea how high it was over 10,000ppm. (whatever the chemicals that were in paper) it wasn't much better in terms of CO2 retention. The paper mask went through 10,000 ppm, which took about an additional minute. I also tested a free linen mask I made (I reviewed l Stuff on Amazon). Surprisingly, this mask does not reduce O2 availability. All other masks I have tried actually reduce the O2 availability in the mask below the OSHA standard of 19.5%. I know because I bought a good quality O2 meter and did a lot of testing. Even my linen mask, which doesn't noticeably reduce O2 levels, retains some CO2. I have seen levels consistently around 2200-2400ppm with peaks in excess of 3500ppm. My testing proves conclusively that most face masks worn by the crowd seriously compromise the quality and safety of the air the wearer breathes. in: headache, drowsiness and stagnant, stale, stuffy air. Difficulty concentrating, loss of concentration, palpitations and mild nausea may also be present. But "do your duty," right?