Air Conditioning, Ventilation, and Respiratory Virus Transmission Potential in South India

Abstract Background Rising global temperatures are expected to increase time individuals spend in under-ventilated spaces and to increase transmission of respiratory pathogens. We studied the impact of ventilation on transmission potential and basic reproductive number (R₀) of respiratory viruses in Puducherry, India. Methods We measured ventilation in thirteen homes and seven healthcare offices. We applied the Wells-Riley equation to estimate the transmission potential and R₀ of SARS-CoV-2 and influenza under different ventilation conditions and viral shedding levels. Results Viral transmission potential was high when doors and windows were closed and highest in the air conditioned (AC) condition. Transmission potential decreased significantly with natural ventilation. R₀ equaled or exceeded 2 in the closed and AC conditions for medium and high virus shedders. Conclusion The transmission potential of respiratory viruses in underventilated homes and healthcare spaces is high, particularly with AC use. Natural ventilation does not reduce R₀ below 1 for super shedders.