Evaluation of airborne particle exposure for riding elevators

Area of Science:

• Environmental Health
• Fluid Dynamics
• Epidemiology

Background:

• Social distancing is crucial for public health during pandemics like COVID-19.
• Maintaining social distancing in confined spaces such as elevators is challenging.
• Airborne particle transmission in shared indoor environments requires further investigation.

Purpose of the Study:

• To investigate airborne particle exposure risks for individuals in elevators.
• To analyze the impact of ventilation rates, air supply, and elevator geometry on particle dispersion.
• To quantify exposure from normal breathing and coughing within an elevator environment.

Main Methods:

• Computational Fluid Dynamics (CFD) simulations were employed.
• Simulations modeled particle dispersion from an index person in a 35-floor elevator.
• Exposure was assessed under various conditions, including different ventilation rates and a simulated cough.

Main Results:

• Elevator rides of typical duration (114 seconds) resulted in low accumulated particle doses for susceptible riders.
• A reference case with 72 air changes per hour (ACH) showed a maximum accumulated particle dose of 1.59 near the source.
• A single cough dramatically increased inhaled particle mass by approximately 8 orders of magnitude compared to continuous breathing.

Conclusions:

• Short elevator rides present a minimal risk of airborne particle inhalation under normal breathing conditions.
• Elevator ventilation and design can influence particle exposure levels.
• Coughing in an elevator significantly elevates the risk of particle inhalation for other occupants, highlighting the importance of respiratory etiquette.