I live near a ten lane highway. I prefer to keep the outdoor air out, and the indoor air filtered. I could see this being very useful for other dwellings though.
With an ERV you can control how much air you get, and put whatever filter you want in between the outside air and your room.
In fact the fancier systems will let you overpressure your house by running the fan pushing in slightly higher than the air pushing out, ensure air only leaks out of your house not in.