Pollution does not generally impact the safety of outdoor activities since it s generally restricted to cities.

Wrong. Pollution DOES generally impact the safety of outdoor activities EVEN TO THE restricted to cities. Pollution does not choose a specific place, wherever it could affect, it will be affected. Since we are living in this planet, pollution affects everyone even though the cause is continents away. Every thing we do creates a ripple effect to the society as well as their outdoor activities since (e.g. smog) is everywhere.  

Iam sorry i do not know the answer