That doesn't follow. The air is cleaner outside than inside. Usually there are more pollutants inside a household (cleaners/plastics/etc) than outside.
If we're just spitballing, then what about the notion that many plastic pollutants function as estrogen analogues? In that case, you'd see less interaction within young women since at worst any estrogen would merely cause precocious puberty. With young men, the effects could be an utterly undefined space.
Sure, the air is. Unless you're taking public transit in a city. And the various kinds of toxic dirt and grime on the streets aren't exactly a picnic either.