Abstract: Based on a three-wavelength detection platform and a dynamic pressure-variable temperature test chamber, the effects of low-pressure environments on the optical extinction characteristics of smoke were investigated, and the mechanism by which low pressure affects aerosol particle characteristics was revealed by combining experimental and mechanistic analyses. Fire experiments were conducted under low-pressure environments of 50, 70, 90 kPa to obtain the optical power and particle number concentration data. The results show that the optical power of smoldering smoke decreases with decreasing pressure, with the minimum optical power value significantly decreasing, the rates of decay and rebound both accelerating, and the time to reach the minimum value being significantly advanced. While the optical power of open-flame smoke exhibits an increasing trend accompanied by intensified fluctuations. The variation in smoke particle concentration is closely related to the combustion behavior.

Key words: variable pressure environment, fire detection, optical power, particle number concentration