Characterization and seasonal distribution of bioaerosols over North East India from the perspective of their impact on human health

Abstract:

Bioaerosols play an important role in spreading biological organisms and reproductive materials (pollens, spores, etc.). These are linked to many different diseases in human, animal and plant. Bacteria and fungi within the size range of 1–10 µm may reach the alveoli of lungs and affect the human respiratory system. Bacterial bioaerosols may cause diseases such as pneumonia, tuberculosis, brucellosis, anthrax, Q fever, etc., whereas, fungal bioaerosols are the etiological agents of respiratory diseases like allergic rhinitis, asthma, etc in humans. Effort was made to distinguish the biological components along with inhalable, thoracic and alveolic particles in aerosol samples collected from nine distinct locations of Northeast India during the year 2018-2019 for the very first time. Thoracic (particles able to track upto thorax of human, basically PM₁₀) contributes to inhalable matter (PM that may be absorbed in the nasal tract with PM ≤ 32 μm, specific for the measuring Bioaerosol spectrometer) significantly (>90%) at all the measurement locations. The contribution of PM₁₀ and PM_2.5 to inhalable matter maximizes and reaches upto ~97% and ~73% respectively in monsoon when bacteria borne diseases predominate in this region. The alveolar (PM < 4 μm, that can reach upto alveoli) component contributes to inhalable matter by 27-56% in winter, 13-67% in pre-monsoon, 30-87 % in monsoon and 26-87 % in post monsoon. The existence of aerosols of non-biological origin is ~30-90% in NER followed respectively by pollens (9-47%), animal debris (1-24%) and fungal spores (1-17%) in different seasons. The concentration of bacteria in air sample in colony formation unit per metre cube (CFU/m³) ranges from 45.5 - 645.84 in post monsoon, 118.06-458.33 in winter, 125.24-632.45 in pre-monsoon and 20.83- 319 in monsoon. All the bacterial species exhibit sensitivity against broad (Chloramphenicol and Ampicilin) and narrow (Vancomycin and Erythromycin) spectrum antibiotics, thereby indicating lesser threat to human health. The predominant microbial genera in the collected bioaerosol samples were identified as Gram positive Diplobacilli sp. followed by Diplococci sp.