Engineered Physical Distance Equivalence for a Cough

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Boeing researchers found the design of the cabin and the airflow system create the equivalent of more than 7 feet (2 meters) of physical distance between every passenger—even on a full flight. The finding is based on a comparison of how cough particles travel inside of an airplane cabin and the spread of cough particles in a still air environment using a conical model.

Using computational fluid dynamics analysis, Boeing researchers tracked particle movement inside the cabin. Based on the airborne particle count of mass in the breathing zone of each passenger, the study found passengers sitting next to one another on an airplane is the equivalent of people maintaining more than 7 feet of physical distance in a still air environment. In the research paper, this is referred to as the engineered physical distance.

Boeing researchers cited several reasons why the cabin reduced passenger exposure to particles:

  • High air exchange rate (cabin air is exchanged 20-30 times per hour; normal buildings have between 2-5 air exchanges per hour)
  • Airflow from ceiling to floor in a circular pattern
  • High efficiency particulate air (HEPA) filters that trap 99.9%+ of particulates in recirculated air
  • Airplane seat configurations act as barriers (forward facing, high-back seating)

For the baseline research, Boeing studied the spread of the particles from a single cough. The modeling and analysis is foundational to studying other scenarios for particle transmission onboard an airplane.