Akila Muthalagu1, Yang Lian2, Rekha M Ravindran3, Asif Qureshi  This email address is being protected from spambots. You need JavaScript enabled to view it.1,4

1 Department of Civil Engineering, Indian Institute of Technology Hyderabad, Kandi, TS 502285, India
2 Indian Institute of Tropical Meteorology, Pune, MH 411008, India
3 State Health Systems Resource Centre, Department of Health and Family Welfare Thycaud, Thiruvananthapuram, Kerala 695014, India
4 Department of Climate Change, Indian Institute of Technology Hyderabad, Kandi, TS 502285, India


Received: August 9, 2023
Revised: October 11, 2023
Accepted: October 27, 2023

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.230191  

Cite this article:

Muthalagu, A., Lian, Y., Ravindran, R.M., Qureshi, A. (2024). Impacts of Floods on the Indoor Air Microbial Burden. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.230191


  • The impact of floods on microbial quality of indoor air and vicinity was assessed.
  • Microbial concentrations were indoor air of flooded houses were 3x than control.
  • Outdoor air and soil contributed to the bacterial burden in the flooded indoor air.
  • Indoor surface dust and outdoor air contributed to the flooded indoor fungal burden.
  • Antibiotic resistant bacteria detected in chlorinated well water, and indoor air.


Floods create a conducive environment for the proliferation of microbes in the indoor air by providing nutrients and moisture and by introducing new microbes from outdoors to indoors. Thus, it is important to better understand the level of proliferation and the characteristics of microbes in the indoor air of flooded built environments. In this work, we address these aspects in a flooded environment in India and investigate the changes in indoor air microbial burden by comparing with the control (non-flooded) houses. Flooded houses within one month of water recession were compared with control houses.  Microbes (bacteria, fungi) were characterized and endotoxins were quantified.  Microbial concentrations were significantly higher in flooded houses than the control houses (p < 0.05). Potential infectious bacterial genera Pantoea, Acinetobacter, and fungal genera Aspergillus, Penicillium were found dominant in the indoor air of flooded houses. Though these fungal genera were also present in the control houses, concentrations were higher (p < 0.05) in the flooded houses. Multivariable regression analysis revealed that indoor air microbial burden was significantly and positively associated with outdoor air and outdoor soil. Further, antibiotic resistant bacteria (ARB) were found in both indoor air, and outdoor water sources (wells) of flooded houses. Our experiments with chlorination revealed these bacteria were resistive to chlorine concentrations > 100 ppm, much higher than those in national and international guidelines. Bacteria were resistant to common antibiotics such as penicillin and ciprofloxacin.

Keywords: Floods, Infectious diseases, Antibiotic resistant bacteria, Chlorine resistance, Built environment

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