Air pollutant mixtures associated with decomposing Sargassum in the Caribbean: Sources, exposure, and potential...

Chronic exposure to air pollutants associated with decomposing Sargassum-including hydrogen sulfide, ammonia, and volatile arsenic compounds-together with anthropogenic emissions and recurrent Saharan dust events, represents an emerging environmental health concern in the Caribbean. Hydrogen sulfide, even at low concentrations (<1 ppm), has been associated with neurotoxic, olfactory, and respiratory effects. Experimental and epidemiological studies further indicate that inhalation of hydrogen sulfide and ammonia may induce chronic lung inflammation, reduced respiratory capacity, and immune dysregulation, including oxidative stress and alterations in the respiratory microbiota. Volatile arsenic compounds such as trimethylarsine (CH₃)₃As and dimethylarsine (CH₃)₂AsH, generated during anaerobic degradation of stranded Sargassum, appear substantially less acutely cytotoxic than arsine, but their long-term health effects remain poorly characterized. Nitrogen oxides (NO and NO₂), emitted mainly by road traffic and industrial activities, contribute to tropospheric ozone formation and may exacerbate pre-existing respiratory disorders through oxidative and inflammatory pathways. Despite the growing number of studies on individual pollutants, current knowledge remains fragmented across atmospheric science, toxicology, and environmental health disciplines. This review provides an integrated synthesis of the potential health impacts of these co-occurring pollutants within a multipollutant framework relevant to the Caribbean context, and highlights the need for integrated exposure assessment, multi-pollutant surveillance, and targeted experimental approaches, including advanced in vitro and complementary in vivo models.