What is an example of a non-excludable good and how does its non-excludability impact its distribution and consumption?

An example of a non-excludable good is clean air. Its non-excludability means that it is difficult to prevent people from benefiting from it, regardless of whether they pay for it or not. This can lead to issues in distribution and consumption as there is no way to limit access or charge for its use, potentially leading to overuse or underinvestment in maintaining its quality.