Are There Risks From Secondhand Marijuana Smoke? Early Science Says Yes

"The inspiration arrived in a haze at a Paul McCartney concert a few years ago in San Francisco."

"'People in front of me started lighting up and then other people started lighting up,' says Matthew Springer, a biologist and professor in the division of cardiology at the University of California, San Francisco. 'And for a few naive split seconds I was thinking to myself, 'Hey, they can't smoke in AT&T Park! I'm sure that's not allowed.' And then I realized that it was all marijuana.'"

"Recreational pot was not legal yet in the state, but that stopped no one. 'Paul McCartney actually stopped between numbers and sniffed the air and said, 'There's something in the air — must be San Francisco!' ' Springer recalls."

"As the visible cloud of pot smoke took shape, so did Springer's idea to study the effects of secondhand marijuana smoke."