Airborne fungi are widely distributed in the environment and originate from various sources like soil, plants, decaying organic matter, and even indoor environments. Exposure to airborne fungal spores can cause allergic reactions, asthma, and respiratory infections. Certain fungi can cause serious infections, particularly in individuals with weakened immune systems. An aerobiological study was conducted to detect airborne fungi using metagenomics in three areas of Mexico City, each representing different degrees of urbanization, during the dry and rainy seasons of 2017. Seasonality showed a significant role in the composition of airborne fungi. Ascomycota predominated in the three areas sampled during dry and rainy seasons, with the genera Cladosporium and Penicillium presenting the highest relative abundances across seasons. The Agaromycetes showed an increase during the rainy season. Regarding the areas, the north and center sites showed similar meteorological conditions and fungal community composition patterns. According to the Shannon and Simpson indices, the south area showed a greater species diversity during the dry season. These insights into the interactions between urbanization, seasonality, and airborne microbial communities could contribute to more effective urban management, reduced health risks, and the promotion of sustainable development.

The Mezquital Valley (Hidalgo, Mexico) faces a severe environmental crisis driven by intense industrial activity and chronic wastewater pollution, factors historically associated with high rates of respiratory and gastrointestinal morbidity. This study assessed the integral biological quality of the air through monitoring and metagenomic profiling of bioaerosols physically associated with PM ₁₀ mass, using high-throughput sequencing of the 16 S rRNA gene (for bacteria) and Internal Transcribed Spacer (ITS) region (for fungi). The results revealed a high diversity of airborne microbiota with distinct taxonomic signatures reflecting a multi-source origin, including soil resuspension, hydro-aerosolization from contaminated water bodies, and industrial emissions. Multiple genera with significant pathogenic potential were identified, notably bacteria such as Clostridium and Pseudomonas , and fungi such as Aspergillus , Penicillium , Alternaria , and Cladosporium . The observed physical adhesion of inorganic particles to these biological propagules suggests a dangerous synergy; exposure to this complex mixture may enhance allergenicity and facilitate the deep penetration of pathogens into the respiratory system, thereby exacerbating health risks. These findings demonstrate that the airborne microbiome in industrial basins is a heterogeneous complex shaped by diverse local loads. Our study highlights the need for multifactorial environmental monitoring strategies that consider the interaction between chemical and biological agents to protect public health in the region.