Did you know that we have no sense of smell while sleeping?

Smoke detectors act as our noses while we sleep and for good reason!

A study undertaken at the Brown University located in the United States of America, conducted an experiment by pumping peppermint and pyridine (a common byproduct of combustion) into the rooms of six sleeping subjects. The subjects were encouraged to sleep in a position that encouraged nose breathing, and over the course of the two nights the scents were pumped into the rooms during various sleeping stages.

The result of the experiment was none of the subjects responded and were awoken by the introduction of these products.


How loud is too loud?


Australian standard 1670.4 2004 sets out the minimal decibel reading that must be achieved where occupants are sleeping AS 1670.4 2004 Fire detection warning control and intercom systems – System design installation and commissioning, states the following;


The A-weighted sound pressure level during the ‘on’ phases of the audible warning signals shall exceed by a minimum of 10 decibels (dB) & the ambient sound pressure level averaged over a period of 60 seconds, shall not be less than 65 dB & not more than 105 dB. If the audible warning signals are intended to arouse sleeping occupants, the minimum A-weighted sound pressure level of the signal shall be 75 dB at the bedhead, with all doors closed. Where occupants, such as patients in hospital wards, must not be subject to possible stress imposed by loud noises, the sound pressure level & content shall be arranged to provide warning for the staff & minimize trauma.”


To give you an idea of everyday noises and their decibels readings

  • Aircraft at take-off (180)

  • Fireworks (140)

  • Chain saw (110)

  • Lawn mower (90)

  • Vacuum cleaner (80)

  • Refrigerator humming (40)

  • Whisper (20)


Is your building compliant?

PRM Fire was recently asked to conduct a fire audit of a fire indicator panel and occupant warning system at a premises located in the central west of NSW. The building was used as sleeping quarters on a regular basis. During the investigation, a decibel reader was used to make sure that the evacuation tones did meet Australians Standards 1670.4 2004.


It was observed that one of the sleeping quarters where four beds were located, did not have the installation of an evacuation speaker inside the room. The nearest speaker was found adjacent to the room in the hallway.  While the correct decibel reading was achieved inside the room, once the door was closed only a decibel reading of 55.3 was achieved at the furthest bed head. It is very common for people in shared accommodation environments to sleep behind closed doors.


PRM Fire produced a report for their client outlining the findings and recommendations of installing an additional evacuation speaker within the room to make sure they were compliant to Australian Standards.

  1. When you alter or retro-fit a building, the adequacy of the fire detection and occupant warning system needs to be considered, as it sits within the new built environment.

  2. When the occupancy type of a building changes, a review of the detection and occupant warning system requires review. Common occupancy changes which may require a strengthening of your systems include:

  • Occupants who have low mobility

  • Occupants who are hearing impaired

  • The storage of chemicals or accelerants

  • Amending housing to boarding/ shared housing where people will sleep with bedroom doors closed

  1. When the hours of operation of the facility expand, the occupant warning system must reflect the lack of observant staff to warn fellow staff members to the existence of a fire or emergency.

Always remember, an occupant warning system needs to be not less than 10db above ambient noise in every workplace. Ensure you test the effectiveness of your system at the noisiest part of your workplace. If staff are wearing hearing protection, other warning systems such as visual strobes or vibration devices will be required.


Contact PRM Fire to make sure your building is compliant today.

For further information, contact PRM Fire services Director Matt Vernon on 0413 066 222.


#smokedetector #smokealarm #prmfire #occupantwarningsystem #australianstandards

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