Depending on their concentrations, sizes, and types, particulate matters of biological origins (bioPM) significantly affect human health. However, for different air environments, they are not well characterized and can vary considerably. As an example, we investigated the bioPM differences at an urban (Beijing) site and a rural (Wangdu) site in the North China Plain (NCP) using an online monitoring instrument, an ultraviolet aerodynamic particle sizer (UV-APS), the limulus amebocyte lysate (LAL) assay, and a high-throughput sequencing method. Generally, lower concentrations of viable bioPM (hourly mean: 1.3 × 10³ ± 1.6 × 10³ m⁻³) and endotoxin (0.66 ± 0.16 EU/m³) in Beijing were observed compared to viable bioPM (0.79 × 10⁵ ± 1.4 × 10⁵ m⁻³) and endotoxin (15.1 ± 23.96 EU/m³) at the Wangdu site. The percentage of viable bioPM number concentration in the total PM was 3.1% in Beijing and 6.4% in Wangdu. Approximately 80% of viable bioPM was found to be in the range from 1 to 2.5 μm. Nevertheless, the size distribution patterns for viable bioPM at the Beijing and Wangdu sites differed and were affected by PM pollution, leading to distinct lung deposition profiles. Moreover, the distinct diurnal variations in viable bioPM on clean days were dimmed by the PM pollution at both sites. Distinct bacterial community structures were found in the air from the Beijing and Wangdu sites. The bacterial community in urban Beijing was dominated by genus Lactococcus (49.5%) and Pseudomonas (15.1%), while the rural Wangdu site was dominated by Enterococcus (65%) and Paenibacillus (10%). Human-derived genera, including Myroides, Streptococcus, Propionibacterium, Dietzia, Helcococcus, and Facklamia, were higher in Beijing, suggesting bacterial emission from humans in the urban air environment. Our results show that different air harbors different biological species, and people residing in different environments thus could have very different biological particle exposure.

Microbiota associated with airborne particulate matter (PM) is an important indicator of indoor pollution as they can be pathogenic and cause serious health threats to the exposed occupants. Present study aimed to investigate the level of culturable microbes associated with PM and their toxicological characterization in urban and rural houses of Pune city. Highest concentration of bacterial aerosols observed to be associated with PM₁₀ size fraction in urban site (2136 ± 285 CFU/m³) whereas maximum fungal concentration has been measured in rural houses (1521 ± 302 CFU/m³). Predominantly found bacterial species were Bacillus sp., S. aureus, and Pseudomonas aeruginosa and fungal species were Aspergillus sp., Cladosporium sp., and Penicillium sp. in both urban and rural residential premises. Concentration of endotoxin measured using the kinetic Limulus Amebocyte Lysate assay exhibited that the level of endotoxin in both urban and rural sites are associated with household characteristics and the activities performed in indoor as well as outdoor. Cell free DTT assay confirmed the ability of these airborne microbes to induce the production of reactive oxygen species (ROS) varying along with the types of microorganisms. On exposure of A549 cells to airborne microbes, a significant decrease in cell viability was observed in terms of both necrosis and apoptosis pathway. Elevated production of nitric oxide (NO) and proinflammatory cytokines in epithelial cells and macrophages clearly suggest the inflammatory nature of these airborne microbes. Results derived from the present study demonstrated that the indoor air of urban and rural houses of Pune is contaminated in terms of microbial load. Therefore, attention should be paid to control the factors favoring the microbial growth in order to safeguard the health of exposed inhabitants.

Previous studies worldwide have suggested the potential role of bioaerosols as ice-nuclei and cloud-condensation nuclei. Furthermore, their participation in regulating the global carbon cycle urges systematic studies from different environmental conditions throughout the globe. Towards this through one-year study, conducted from June 2015–May 2016, we report on atmospheric abundance and variability of viable bioaerosols, organic carbon (OC) and particles number and deduced mass concentrations from Indo-Gangetic Plain (IGP; at Kanpur). Among viable bioaerosols, the highest concentrations of Gram-positive bacteria (GPB), Gram-negative bacteria (GNB) and Fungi were recorded during December–January (Avg.: 189 CFU/m³), November (244 CFU/m³) and September months (188 CFU/m³), respectively. Annual average concentration of GPB, GNB and Fungi were 105 ± 58, 144 ± 82 and 116 ± 51 CFU/m³. Particle number concentration (PNC) associated with fine-fraction aerosols (FFA) predominates throughout the year. However, mineral dust (coarser particle) remains a perennial constituent of atmospheric aerosols over the IGP. Temporal variability records and significant positive linear relationship (p < 0.05) of GPB and GNB with OC and biomass burning derived potassium (K⁺BB) indicates their association with massive emissions from paddy-residue burning (PRB) and bio-fuel burning. Influence of meteorological parameters on viable bioaerosols abundance has been rigorously investigated herein. Accordingly, ambient temperature seems to be more affecting the bacteria (anti-correlation), whereas wet-precipitation (1–4 mm) relates to higher abundance of Fungi. High abundance of GNB during large-scale biomass burning emissions has implications to endotoxin exposure on human health. Field-based data-set of bioaerosols, OC, PNC and deduced mass concentrations reported herein could serve to better constraint their role in human health and climate relevance.