Final answer:
The question pertains to fire safety law, specifically the maintenance of smoke detectors and the requirement for cleaning intervals, which is determined by local regulations and performed by a certified professional with an S-97 or F-78 Certificate of Fitness.
Step-by-step explanation:
Smoke detectors are critical safety devices that require regular maintenance to function effectively. The frequency at which smoke detectors need to be cleaned or serviced may depend on local laws and regulations, which are often established by fire safety codes. To answer the question of how often smoke detectors should be cleaned, you would need to refer to the specific regulations in your area. These regulations might state that smoke detectors must be cleaned every 6 months, annually, or some other interval by a certified professional holding an S-97 or F-78 Certificate of Fitness. Holders of these certificates are trained and authorized to perform maintenance on fire safety equipment.