Influence of Light Wavelengths on Visibility in Smoke during a Tunnel Fire

The occurrence of fire in road tunnels poses high risks to the life and health of people. The resulting smoke, fire gases and high temperatures can be the cause of poisoning and burns. Additionally, dense smoke can significantly reduce visibility, which can result in difficulties during evacuation. This paper aims to investigate the effect of specific wavelengths of visible light on visibility in smoke conditions and to determine the wavelength of light (colour) that can improve visibility in smoke-filled environments. A rubber mixture with polyester and polyamide spacers was selected as a combustible material in order to obtain more realistic conditions with respect to smoke parameters. These plastics are commonly used, among others, in tires, elements of engine plating, upholstery or truck trailer covers. Then, in a test fire chamber laboratory, the colour of light (wavelength) was determined, obtaining the highest transmittance value, understood as the amount of radiation transmitted through the substance. It has been shown that devices emitting a light wave of a specific length can significantly improve visibility in smoke-filled environment.