Working residential smoke alarms are an important life-saving technology as they provide early warning to occupants in order to enable adequate egress time. As homes have evolved over the years from how they are designed to the materials in the home, it is important to understand how the changes impact occupant egress time in the event of a fire.

As a safety science organization, UL conducted several research projects to better understand smoke characterization and its impact on smoke alarm technologies. UL also undertook additional research to better understand and address cooking nuisance alarming. The goal and outcome of UL research is to develop criteria that will improve the performance of smoke alarm technologies.


Smoke Characterization Project

In order to better understand the dynamics of smoke in today’s modern home, UL, with the support of FPRF, initiated research to more fully characterize the products of flaming and non-flaming combustion. The products and chemistries commonly found in today’s residential settings were investigated in order to understand how materials in homes burn differently and how that might impact the safe egress time of occupants. Click here to view the full report. 


Polyurethane Foam Test Project

The Smoke Characterization Project showed that polyurethane foam produced smoke characteristics that are different from those currently used to evaluate smoke alarms under 217. The 217 STP created a Task Group to develop new flaming and smoldering polyurethane foam fire tests to complement existing UL 217 and UL 268 tests and to increase available egress time.

Data from that project can be found here:

Data file overview (*.xlsx)

Flaming Tests (all files have been compressed into ZIP format)

Smoldering Tests (all files have been compressed into ZIP format)

Equivalent data collection on the three UL 217 flaming tests (flammable liquid, wood and paper) are captured in the following link:

Results from the investigation of various approaches to uniformly disperse smoke generated by smoldering foam in order to reduce alarm location dependency during the course of testing can be accessed via the following link:


Cooking Nuisance Alarm Research

Homeowner’s response to nuisance alarming has been identified as one of the reasons for disabling of smoke alarms. As revisions to UL 217 and UL 268 were being considered, it was imperative to also address nuisance alarming. The research project enabled UL to develop recommendations for revisions to the standards through the determination of a representative nuisance cooking source and parameters for standardized testing. Click here to view a white paper on the characterization of smoke alarm nuisance sources from cooking scenarios.