What do they teach in schools now? Do they skip biology and instead have them read Al Gore's book on climate change? Del Allen's March 7 letter "Protect our oxygen supply" is a good example. It's been almost 60 years since I went to school, but I do remember being taught that plants make oxygen and need carbon dioxide to do it. These gases get recycled by plants through the process of photosynthesis and convert it to oxygen. So plants are not competing for oxygen. Allen's on the wrong bandwagon. Carbon dioxide is not a killer, silent or otherwise. We ourselves exhale it.
Then let's look at how oxygen generators work. They make oxygen from water using electrolysis, which takes electricity, which in turn is generated in part by coal-fired generators. So you need coal for that, and you need oil to make gas, which many use to commute to work and go to the store, which uses gas-burning trucks to get the goods there, and oil is used in the manufacturing of many items in the home -- plastics for example.
And who will pay the oil transporting people to stay home? Certainly not the oil companies if they can't make money transporting it.