This website is an atmosphere design lab from the Smithsonian Institute. You can adjust the levels of carbon dioxide, oxygen or ozone in the atmosphere. Once you choose a gas, there are statistics about the levels of that gas in the atmosphere and what would happen if you changed the levels. There are also helpful examples from other points in history when different levels of these gases were present. For example, if you have more oxygen than the average amounts found on earth today, there would be a chance of things spontaneously combusting. This interactive site is helpful for people who want to learn more about the composition of the earth’s atmosphere but don’t know where to start.
A picture of the site is below.