Optical smoke detectors react too slowly
Tests for Norway’s Civil Protection Directorate conclude that optical smoke alarms can take 2 – 3 hours to sound in case of smouldering fires, whereas during this time the carbon monoxide (CO) accumulation could be sufficient to prevent occupants from awakening. Norway legislation requires smoke alarms to be installed in all homes, and optical alarms are recommended.
In a separate survey of 624 dwellings in Norway, 98% had a smoke alarm installed, and 90% of these were correctly operational.
“Kartlegging av gasskonsentrasjoner, effekt av dødluftsrom og effekt av alternativt deteksjonsprinsipp ved ulmebrann” (Measuring gas concentrations, effect of dead-air space and effect of alternative detection principles in the case of a smouldering fire) www.spfr.no “Kartlegging av bruk av røykvarslere i boliger” (Mapping the use of smoke detectors in Norwegian dwellings) www.spfr.no