Kelly wrote:

How can I determine the source of cigarette smoke that has been coming
into my apartment so I can block it.

I live on the third floor rear of a six-floor brownstone in NYC. There
are two apartments on each floor, front and rear (except one on the
6th). I believe that only the people in the fourth floor front smoke.
All my windows face a backyard area. The backs of a restaurant up the
block and two large apartment buildings also face this area.

My building has no central air conditioning system. I've closed off the
two exhaust vents (in the kitchen and bathroom) with thick plastic and
duct tape.

Lately, I have noticed a constant smell of cigarette smoke, usually
starting mid-day and lasting until 4 a.m. or 5 a.m. This goes on for a
few days or a few weeks and then stops for a few days or a few weeks and
then starts again. The the people in the first floor rear apartment
have also noticed it.

The smell is strongest in my bedroom, which is farthest away from the
smokers in the front apartment upstairs.

I suspect that the smoke is from the restaurant's exhaust, due to the
hours I smell it. And I think I only smell it sometime because of
changes in wind direction. (I just thought of this and will keep track
of that going forward.)

But I'm not sure, and it may be that some is also entering my apartment
from somewhere in my building.

Are there any tests or chemicals to determine the source of the smoke?

Thanks for any help.

Ellen

Finding the source won't do much other than satisfy your curiosity.
Sealing up possible entries is the way to take care of it. Air car
migrate unit to unit through wall openings, and there are gaps at bottom
of walls and around electrical openings. Caulk around bottom of
baseboards to seal off those as much as possible. A foam insulation
around light fixtures and wall outlets might help. Anything with an
exhaust that draws air into the apartment will pull air in under doors
and leaky areas around windows.