How many times has your LO been exposed to thirdhand smoke? This could be something like visiting the home of someone who smokes (not while they're actively smoking), or standing in line at the grocery store next to someone who reeks of smoke.

I'm wondering if my daughter has had a lot of exposures or if she's had a normal level of exposure. I know that there's no "safe" level but it's impossible to avoid fully since there are smokers everywhere you go.