Scientific Experiences in Mechanical Engineering

Abstract
Vehicle cabin air quality has become an important concern due to the accumulation of airborne pollutants in enclosed environments. In addition to emissions from interior materials, car perfumes may influence airborne particle formation through the release and evaporation of fragrance-related volatile compounds, particularly under elevated temperatures caused by solar exposure. This study investigated the effects of different car perfume types on vehicle cabin air quality through measurements of airborne particle concentrations and characterization of perfume chemical compositions using Fourier Transform Infrared Spectroscopy (FTIR). Experiments were conducted using a Daihatsu Gran Max vehicle exposed to direct sunlight under four conditions: without perfume, liquid perfume, gel perfume, and solid perfume. Particle concentrations at six particle sizes (0.3, 0.5, 1.0, 2.5, 5.0, and 10.0 µm), cabin temperature, and relative humidity were recorded at 30-minute intervals over a three-hour period. The results showed that cabin temperature increased from approximately 24–28°C to more than 45°C during solar exposure, while relative humidity decreased substantially. The liquid perfume produced the highest concentration of 0.3 µm particles, reaching 100,089 pcs/L, representing a 56.2% increase compared with the control condition. The gel perfume increased particle concentration by 46.1%, whereas the solid perfume exhibited the lowest particle levels throughout the experiment. FTIR analysis identified several volatile-related functional groups, including hydroxyl, aliphatic, ester, phosphate, nitro, and fluorinated compounds. The liquid and gel perfumes exhibited a greater abundance of volatile-related functional groups, which corresponded to their higher airborne particle concentrations. These findings demonstrate that car perfume formulation significantly influences airborne particle dynamics inside vehicle cabins under solar-heated conditions and suggest that low-volatility perfume products may help reduce occupant exposure to airborne pollutants in tropical environments.

Keywords: Vehicle interior air quality; Car perfume; Airborne particles; FTIR; Solar exposure; Particle concentration.