Experimental assessment of gas-phase air quality improvement using camel hair–leather composite filters

Indoor air quality (IAQ) in hot-arid regions is increasingly compromised by tightly sealed building envelopes, limited ventilation, and the accumulation of gas-phase pollutants. While camel-hair–leather composite panels have previously demonstrated effectiveness as particulate pre-filters, their gas-phase filtration performance remains unexplored. This study evaluates the attenuation of the gas phase of a mixed combustion aerosol — incense smoke — by such a bio-based composite; no species-resolved gas concentrations and no particulate mass were measured. The specimen tested was a disc formed of conditioned camel hair alone, containing no leather substrate layer. A custom cylindrical test rig was developed, integrating dual ESP32-based sensor nodes equipped with MQ135 metal-oxide gas sensors and SHT35 temperature–humidity sensors positioned upstream and downstream of the filter. Continuous incense smoke was introduced under forced airflow conditions over a ~ 37.5-min test period in a single, non-replicated proof-of-concept run. Attenuation was quantified from the paired upstream and downstream sensor outputs as a relative, non-speciated index, alongside temporal and categorical air quality analyses. Mean attenuation was 14.3% (95% CI ≈ 7–22%), with peak attenuation of 25.3% during high-concentration events and approximately 5.0% at steady state, reflecting concentration-dependent adsorption behavior. The filter reduced high-pollution episodes, decreasing “poor” air quality classifications from 9.4% upstream to 2.1% downstream. Transient episodes of negative attenuation observed mid-test are consistent with adsorption–desorption dynamics within the composite matrix, although sensor cross-sensitivity to the concurrent hygrothermal changes and the transport delay between the two measurement positions cannot presently be excluded. Hygrothermal analysis revealed a downstream temperature increase of + 0.58°C and relative humidity reduction of − 2.14%, consistent with hygroscopic moisture buffering by the keratin fibre matrix. These findings identify the camel-hair–leather composite as a low-cost, bio-based, multi-functional filtration medium with promising gas-phase attenuation for sustainable IAQ strategies in arid-climate buildings; replicate runs and validation against an orthogonal analytical technique are required before the mechanistic interpretation can be regarded as established.