My house smells like weed from the first floor apt. I live on the 3rd this is everyday not too strong tho will this affect my 16 m old?

No, you cannot absorb enough THC from second-hand smoke unless it's quite concentrated in the environment (i.e. what's known as "hotboxing".) Hence, you wouldn't even drug test positive on this, absent an extremely sensitive test. (which aren't used in common practice.) As a rule, you'll know if you've been affected fairly quickly. You'll experience what is known as a "contact high" which is quite apparent when one experiences it.

Do you really want to know pretend that you're cutting a little piece of hair from your 16 year old boys head because it's out of place or wait till he goes to the barber shop and get a hair sample and have it sent off and have a lab analysis for drugs done on the hair sample where there is weed you will find that 16 year olds are smoking it want to find out get a hair sample and have it sent out

No. I always wondered if when firefighters are putting out a fire on a massive weed garden if the smoke gave them a buzz.

No, it will not affect your young one and it is way overly paranoid that you would think it could.