How careful should I be about 2nd hand smoke?

Katie • Veggie mama
Hi all! I'm about 7 weeks pregnant and still keeping it a secret from most people. I've been very careful about staying away from friends who smoke, but I work in a city and I run into smokers on sidewalks and get really concerned when I can't avoid them. I try to hold my breath, but is that worse? And is just a couple of seconds of smoke daily enough to hurt my baby?