Hi. Dos anyone know of a plumbing company in the Los Angeles area that can smoke test the vent system at a residence?

We have an odor problem in the house and there are no visible signs of a leak. I have read about a smoke test where the roof vents are capped off and the main drain plugged. Smoke is then injected into the plumbing to see if it leaks out from anywhere.

While the odor does not smell like sewage, we can not pin point the exact location of the smell. We would like to rule out a simple vent leak.

We have been unable to find a company that actually does this kind of work in Los Angeles.

Thanks.