At a high enough level, CO₂ is lethal. There have been deaths due to CO₂ leaks from tanks providing the gas to soda machines. In some countries, there are laws and restrictions connected to tanks where people work with the gas. Carbon dioxide can easily be confused with carbon monoxide (CO). There is also confusion about what gas to look for. For instance, today's cars emit more CO₂ than CO. We strongly recommend that CO₂ be monitored as well as CO in parking houses. Carbon dioxide in itself is not poisonous, but it decreases the concentration of oxygen when in the same confined space. Our sensors are able to detect other gases, but you will find many alarm applications sensing CO₂.
% instead of PPM
If you just learned what ppm stands for, it might be confusing that the alarm world talks about %. There is a reason, however. Since alarms usually work with high levels of concentration, ppm figures become too large to handle.
100% = 1,000,000 ppm
1% = 10,000 ppm
So, how do we translate percentage to the alarm world?
Fresh air contains 0.04% CO₂. When CO₂ rises to 1.5% (15,000 ppm), your heart rate may increase, and at 4% (40,000ppm) you are in immediate danger.