Why can the Free Rider Problem extend into the Environment? Use Air as an Example

-Air is a Public Good - Non-Excludable and Non-Rivalry -Clean & Dirty Air will Cost the Same [Nothing] so making Clean Air Scarce won't Rise its Price up and Deter People from 'Usage' -This means the Benefits of not Polluting the Air, or Cleaning the Air, will not be Restricted to those who 'Paid' for the Clean Air [Non-Diminishing] so in a Free Market, its Rare to see that Happen