The last company used an ozone machine and it still smells. Why?

Ozone treats air, not resin on walls, fabrics, and ducts. The residue itself has to be cleaned or neutralized.

Can my painter just cover the yellow film?

Paint over resin tends to bleed through. Washing the walls comes first, and a sealing primer goes on before the finish coat.

Maybe not. Years of high humidity can leave moisture damage or mold behind, and that has to be checked before any deodorizing.

Not for a whole-house chlorine dioxide treatment. Ask for the out-and-back-in times before booking.

Yes. Ask for a written scope and quote before any treatment begins.

The last company used an ozone machine and it still smells. Why?: Ozone treats air, not resin on walls, fabrics, and ducts. The residue itself has to be cleaned or neutralized.
Can my painter just cover the yellow film?: Paint over resin tends to bleed through. Washing the walls comes first, and a sealing primer goes on before the finish coat.
The basement was a former grow. Is odor the only issue?: Maybe not. Years of high humidity can leave moisture damage or mold behind, and that has to be checked before any deodorizing.
Can my family stay in the house during treatment?: Not for a whole-house chlorine dioxide treatment. Ask for the out-and-back-in times before booking.
Should I get the cost in writing first?: Yes. Ask for a written scope and quote before any treatment begins.