What to ask, and why
Will exposed brick soak up the treatment and still smell?
Brick is porous. It may need surface treatment and, if heavily affected, cleaning and sealing. Ask what's recommended for your walls.
I aired it out for a week. Why does it still smell?
Open windows clear the air but not the tar film on brick, ductwork, and upholstery. Until that film is broken down, the loft keeps re-scenting itself.
Will my landlord's move-out inspection catch it?
Probably. Treating before the walkthrough is easier than disputing a deduction afterward.
Does the shared building air need treatment?
If odor travels through shared ducts, the building manager may need to be involved. Ask what can be treated within your unit.
How do I know a provider won't just mask it?
Ask directly whether ozone, bleach, or fragrance will be used, and what will be done to the residue on brick, ducts, and fabric.