The phrase "clean air" refers to the quality of the air we breathe. It means that there are no harmful pollutants or particles present in the air, making it safe and healthy for us to breathe in. Full definition
But just how large are the health benefits of cleaner air in comparison to the costs of reducing carbon emissions? (sciencedaily.com)
From here, the fight for greater equality and the economic rights of the middle class — as well as for cleaner air & energy — only stands to gain momentum. (treehugger.com)