Explain why air pollution on a global scale can affect air quality on a local scale?

The vast pollution which occurs globally can have a significant impact on air quality on a local scale. The reason for this is quite simple: polluted air can easily get trapped beneath a cloud cover, or be literally "blown" away to other locations, and when much polluted air gets accumulated, it can have devastating heath effects on a local population, not just to humans, but to animals and plants as well. Overall, the vast global pollution can effect the smallest of regions on an unprecedented scale.

i think the answer to your question is: settlement of the interior and economic growth. ( ^_^)／