Les substances chimiques (ជាតិគីមី jāti gīmī) présentes dans l’alimentation font l’objet d’une préoccupation collective croissante au Cambodge. Malgré leur caractère invisible, l’idée selon laquelle les aliments contiennent des résidus chimiques néfastes pour la santé, a fait son chemin. Tout un ensemble de peurs alimentaires émergent. Un nouvel imaginaire des aliments se répand et chacun tente de mettre en place des stratégies pour s’arranger avec la peur de la contamination. À partir d’une étude ethnographique réalisée au Cambodge entre juin 2018 et mars 2019 auprès de citadins, d’agriculteurs, de vendeurs de riz, de produits frais et de vendeurs d’intrants agricoles, cet article rend compte des imaginaires collectifs des aliments et des accommodements qui s’élaborent en réaction à la peur de la contamination.

Airborne microplastics (AMPs) are increasingly recognized as an emerging air pollutant. However, observational data remains scarce in Southeast Asia. This study provides the first observations of AMPs in Phnom Penh, Cambodia, using µFTIR-ATR imaging. Number concentration, morphology, polymer composition, aerodynamic size distribution, Feret diameter, and surface aging characteristics were investigated together with meteorological parameters, gaseous pollutants, water-soluble ionic tracers, and HYSPLIT backward trajectories for source attribution. AMPs were dominated by polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with 52% classified as fragments and 82% having Feret diameters smaller than 30 µm. AMP concentrations ranged from 0.55 to 1.27 MP m^-3 in TSP (mean: 0.97 ± 0.30 MP m^-3, n = 134) and from 0.23 to 0.49 MP m^-3 in PM2.5 (mean: 0.33 ± 0.10 MP m^-3, n = 46). Carbonyl and hydroxyl indexes indicate that PE and PP were relatively fresh and in low-to-moderate photo-oxidative aging states. Correlation analysis further indicates that PE and PP were mainly associated with local waste fragmentation, whereas PET was linked to precipitation scavenging and resuspension processes. In addition, HYSPLIT backward trajectories suggest regional transport of AMPs by the Southwest Monsoon from marine source regions, including the Indian Ocean, Arabian Sea, and Andaman Sea. These findings provide the first baseline dataset for AMP pollution in Phnom Penh, Cambodia and highlight the combined importance of local emissions and regional atmospheric transport in Southeast Asia.

Airborne microplastics (AMPs) are increasingly recognized as an emerging air pollutant. However, observational data remain scarce in Southeast Asia. This study provides the first observations of AMPs in Phnom Penh, Cambodia, using µFTIR-ATR imaging. Number concentration, morphology, polymer composition, aerodynamic size distribution, Feret diameter, and surface aging characteristics were investigated together with meteorological parameters, gaseous pollutants, water-soluble ionic tracers, and HYSPLIT backward trajectories to examine possible source attribution. AMPs were dominated by polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with 52% classified as fragments and 82% having Feret diameter smaller than 30 µm. Across four independent 72-h sampling periods (n = 4), AMP concentrations ranged from 0.55 to 1.27 MP m⁻³ in TSP, with a mean ± standard deviation of 0.97 ± 0.30 MP m⁻³, and from 0.23 to 0.49 MP m⁻³ in the PM_2.5 fraction, with a mean ± standard deviation of 0.33 ± 0.10 MP m⁻³. In total, 134 particles were identified in TSP, of which 46 were detected in the PM_2.5 fraction. Carbonyl and hydroxyl indices indicated that PE and PP were relatively fresh and in low-to-moderate surface aging states. Pearson correlations suggested that the abundances of individual polymers were varied differently in relation to local environmental and precipitation-related variables; however, the limited number of sampling periods precludes source or process attribution. In addition, HYSPLIT backward trajectories showed that some air masses arriving in Phnom Penh had passed over marine regions under southwest monsoon flow. These findings provide the first baseline dataset for AMP pollution in Phnom Penh, Cambodia, and highlight the combined importance of local emissions and regional atmospheric transport in Southeast Asia.

Phnom Penh, the rapidly urbanized capital city of Cambodia, faces significant challenges from air pollution. Air pollutants, including gaseous compounds such as nitric oxide (NO), nitrogen dioxide (NO ₂ ), nitrogen oxides (NO _X ), ozone (O _s ), and carbon monoxide (CO), impact public health and can serve as indicators of direct emission sources that may vary seasonally. This study characterized the seasonal variability of these gases over three months in the rainy (August-October, 2024) and dry (January-March, 2025) seasons in Phnom Penh. In the rainy season, NO, NO ₂ , and NOx exhibited higher concentration, while Os levels were elevated in dry season. These patterns suggest seasonal differences in dominant emission sources between vehicular emissions and biomass burning, as well as distinct atmospheric chemical processes. CO concentrations remained relatively stable across seasons. Meteorological factors, including precipitation and temperature, displayed limited influence on these gaseous pollutant levels, whereas wind speed showed weak correlations. Diurnal patterns revealed morning and evening peaks in NO, NO ₂ , NO _x , and CO associated with rush hours, while ozone peaked in the afternoon, corresponding to peak sunlight intensity.

This study examines the seasonal and diurnal variations in ultrafine particles (PM_0.1) and their carbonaceous components (OC and EC), collected at the Institute of Technology of Cambodia in Phnom Penh. Sampling was conducted over 14 consecutive days in September 2024 (during the wet season) and February 2025 (during the dry season). The average mass concentration of PM_0.1 in February (8.5 μg/m³; range: 3.9–11.3 μg/m³) was approximately three times greater than that in September, driven by a corresponding increase in OC concentration. Conversely, average EC concentrations remained almost stable across both seasons, indicating consistent local emission sources. Total carbonaceous compounds (OC + EC) constitute approximately 50% of the PM_0.1 mass in both seasons. Primary organic carbon (POC) concentration increases almost four times in February compared to September. Secondary organic carbon (SOC) concentrations were significantly elevated during February daytime (1.4 ± 1.0 μg/m³), indicating active photochemical formation. Backward trajectory analysis and satellite hotspot data revealed that September air masses originated from maritime sources without significant local burning influences, while February pollution events were likely influenced by short-range transboundary transport from biomass-burning areas across the Cambodia–Vietnam border.