As the site visit, current spot type smoke detector installations in mezzanine floor are located much lower away from the room ceiling level. The current installation might lead delay of fire detection & fire notification during the initial fire stage.
Referring to NFPA 72 “National Fire Alarm and Signal Code”- 2013 Edition, spot type smoke detectors shall be located on the ceiling or between 300mm. lower from ceiling for sidewall detectors as following figure: