Radon diffusion image

Anyone have a nice drawing/image showing how radon enters a home? Maybe something showing plumbing penetraions, crack in the floor, etc and then shows how it diffuses out the upper floors? I’m putting together a presentation/course for marketing/CE purposes.

Thanks Mike, I looked all over epa’s web site, and missed this.

http://www.epa.gov/radon/pubs/physic.html#Character image on left, A-K