Hello Mr. wood its Ethan from your first period and i have the answer to one of your questions if the carbon dioxide levels become to high humans will get poisoned.In fact a lot of people will die because of this levels.Since the levels in the past years have sky rocketed we need to take percautions such as buildings that will not have those poisones gases in them.Thats all i have for now ,but i might answer your another one of your questions.Bye.