With the holiday travel season behind us, aircraft workers may have an unpleasant, lingering reminder in the form of a cold or the flu. As these workers, and other frequent fliers, may have long suspected, the cabin’s air sometimes contains germs.
At NIOSH, research engineers study the health effects of air on worksites, including how far germs can scatter in the confined space of an aircraft cabin traveling at typical cruising altitude.
A critical part of maintaining a safe work environment during flight is regulating the airflow. Of course, studying airflow in a moving aircraft presents obvious difficulties, so NIOSH engineers use realistic mock-ups of aircraft cabins, rather than boarding a flight, to conduct experiments that simulate various conditions.
They then use the results build a model to predict how substances, such as airborne contaminants, travel through the air and interact with surfaces.
In a study with university partners, NIOSH engineers developed a tool using this technique to study the airborne transmission of simulated contagious substances from an imaginary passenger source. Using an 11-row mock-up of a twin-aisle passenger jet with seven seats per row, they collected information from releases of tracer gas, inert particles, and live bacteria.
The model built from this information data was remarkably similar to a case study stemming from a flight affected by a respiratory illness. In that instance, flight attendants and passengers flying from Hong Kong to Beijing on March 15, 2003, contracted severe acute respiratory syndrome (SARS).
Next, the engineers created the tool, or interactive “exposure map.” This computerized diagram of an aircraft cabin’s seating area calculates the relationships between contaminants, surfaces, workers, and passengers, with a click of the computer mouse on various map locations.
Study results indicated that exposure to contagious substances via small, airborne droplets occurred across several rows, according to the paper published in the journal HVAC&R Research. Now, it is important to improve the tool’s accuracy by incorporating additional information from different types of aircraft and passenger cabins, sources, including live virus, as well as from diverse computer-generated calculations.
NIOSH engineers continue research to measure the risk of exposure to infectious diseases while working on aircraft. For example, they are studying how airborne viruses disperse in single- and twin-aisle cabins and have submitted a paper on this project to the American Society of Heating, Refrigeration and Air-conditioning Engineers 2018 Annual Conference.