New London Architecture

Research Study Finds Short Elevator Ride with Simple Mitigation is Comparative Low Exposure Amid Pandemic

Tuesday 02 March 2021

Stephen R. Nichols

Associate Director, Systems Engineering & Innovation
Otis UK & Ireland

The need for science-based information
Elevators play an essential role in keeping people on the move, every day. Given what scientists now know about how COVID-19 is spread, people naturally have questions about the relative risks of congregating in common spaces, including elevators. As an industry leader, Otis is committed to finding answers that are based on rigorous scientific methods and the expertise of leading researchers in the field. As you will learn below, the research findings show that elevator travel is on the lower end of the exposure spectrum when coupled with simple mitigation, including the proper use of masks.
 
About our elevator airflow study
To provide the riding public and our customers with science-based information and solutions, Otis commissioned a three-month academic research study focused on understanding the relative risk of COVID-19 exposure in elevators. This research was led by Dr. Qingyan (Yan) Chen, the James G. Dwyer Professor of Mechanical Engineering at Purdue University, who worked collaboratively with Otis elevator system experts.
 
With science continuing to point to respiratory droplets and aerosols as a principal means of transmission, the study focused on airflow and the impact of ventilation rates and types, purification technologies (specifically needlepoint bipolar ionization) and simple mitigation strategies in elevators.
The study methods used state-of-the-art computational fluid dynamics (CFD) modeling to simulate airflow to replicate particle dispersion during several two-minute elevator rides. For the elevator ride, we modeled multiple scenarios, including particle dispersion when the doors open as passengers get on and off the elevator.  The combination of CFD and other modeling techniques allowed us to look at the movement of air, particles in the air, the people and the elevator itself.
The average elevator ride
The average elevator ride is short – typically less than one minute – limiting the duration a passenger is exposed to the virus. In addition, all elevator codes require openings for ventilation. By design, elevators have a high level of air exchange. Higher airflow reduces the number of airborne particles by removing them from the elevator.
Variation of intensity, frequency and duration of exposure contributes to different degrees of exposure even within each activity category
Adapted from relative framework originally proposed by Julie Marcus at Harvard and Eleanor Murray at Boston University
Risk of exposure in elevators can be lowered by applying proper mask usage, air purification (like NPBI), physical distancing, etc.

Our findings
Coupled with what we already know about elevator design and operation, the study findings support the idea that elevator travel with simple mitigation represents a relatively low risk of exposure, comparable to a trip to the supermarket and lower exposure risk than outdoor dining.
 
In short, the high level of air exchange in an elevator lowers the exposure risk. The higher the elevator ventilation rate, the lower the accumulated dose* a passenger is potentially exposed to.
 
Proper use of a surgical-style mask by all passengers, reduces exposure risk an additional 50%.  The addition of a common type of air purification called needlepoint bi-polar ionization reduces exposure risk an additional 20 to 30%.  These two mitigation strategies combined can reduce exposure risk a total of 60 – 65%.
 
Moving you (and moving forward):
This study and its findings are just a part of our commitment to providing science-based information 
throughout the COVID-19 pandemic and into the future. The full study will be submitted for future publication in academic journals later this year. 
 
Visit our innovation page on otis.com to view the white paper detailing the findings and other resources related to the study, along with solutions and strategies for limiting passenger exposure to the virus.

* Accumulated dose is the amount of virus a person is exposed to and depends on intensity, frequency and duration of exposure. Quantifies the relative risk of exposure.


Stephen R. Nichols

Associate Director, Systems Engineering & Innovation
Otis UK & Ireland



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