Helmet heat protection reduced by colour and soot, says French research
A new study has found that firefighter helmets lose their ability to reflect heat depending on their colour and surface condition.
According to Fire Safety Journal, Volume 155, chrome plated helmets reflected up to 83 percent of radiative heat, while coloured variants showed reflectivity as low as 3 percent.
When contaminated by soot or combustion deposits, reflectivity dropped to around 36 percent, even for chrome helmets.
The research, led by A. Collin and colleagues in France, analysed 16 helmet samples currently in use by Fire and Rescue Services across France, England and Canada.
The study focused on directional-hemispherical reflectivity and absorptivity across infrared wavelengths, measuring how helmets performed at temperatures up to 1000 K (727°C /1340°F).
Helmet types and thermal performance examined
The study used infrared spectrum analysis to examine heat reflection in helmets used in emergency response.
Chrome plated helmets showed the best thermal protection by reflecting most radiative energy and limiting absorption.
Coloured helmets had much lower reflectivity, depending on pigment, with red helmets absorbing nearly all heat exposure.
Soot or other residue significantly reduced reflectivity, regardless of original surface, suggesting that maintenance and cleaning influence thermal protection.
The findings build on earlier experimental work, including that of Barnett (2003), who studied abrasion and surface degradation in helmet materials under high heat.
Sample and standards used in testing
Sixteen helmets were tested as part of the research.
All samples met EN 443:97, the European standard for firefighter helmets.
The helmets were sourced from French fire departments including SDIS 54 (Meurthe-et-Moselle) and SDIS 49 (Maine-et-Loire), as well as from LCPP (Laboratoire Central de la Préfecture de Paris).
The helmets varied in colour and manufacturer, but none were named for confidentiality reasons.
Measurements were taken across different points on each helmet to assess consistency in performance.
Research context and motivation
The study responds to concerns about rapid helmet deterioration during use or training.
Infrared reflectivity, especially in contaminated helmets, is a major factor in heat protection for personnel in radiative environments.
The authors cite previous studies into garment protection, water spray use and nozzle dynamics, noting that helmets remain under-studied in heat transfer literature.
The research was intended to quantify radiative properties across real-world helmet types and provide data for future equipment design and policy decisions.
According to the authors, all raw data are available in a publicly accessible database.
Implications for firefighter safety and equipment design
The study reinforces the thermal advantage of chrome helmets under clean conditions.
It also highlights the need for regular cleaning to maintain heat protection levels during live incidents and drills.
The reduction in reflectivity from surface contamination may increase the risk of thermal injury in high-flux environments such as flashovers or backdrafts.
The researchers recommend greater awareness of surface degradation and cleaning protocols.
Future helmet designs may need to incorporate materials or coatings that retain reflectivity even after exposure to soot or abrasion.
Helmet reflectivity study reveals thermal risks from colour and soot: Summary
Fire Safety Journal has reported that helmet colour and soot contamination reduce the ability of firefighter helmets to reflect heat.
The study was conducted by researchers including A. Collin and Z. Acem in France.
It tested 16 helmets currently used by fire services in France, England and Canada.
Chrome plated helmets reflected an average of 83 percent of radiative energy at 1000 K.
Coloured helmets reflected between 3 and 14 percent of heat depending on pigment.
Soot reduced reflectivity to around 36 percent, even for chrome helmets.
The study used infrared spectrum measurements to assess heat reflection and absorption.
All tested helmets met EN 443:97 standards.
Previous research has shown helmets degrade during use, causing blistering and reduced surface performance.
The findings highlight the importance of cleaning and maintenance.
Raw data from the study are available in a public-access database.