Aircraft cabins may have the lowest levels of aerosol particles, Shaw’s study

If you’re looking for an indoor space with low levels of particulate air pollution, a commercial airliner flying at cruising altitude is probably the best option.

Newly reported studies of air quality in indoor spaces such as stores, restaurants, offices, public transport, and commercial jets show aircraft cabins with the lowest levels of small aerosol particles.

The July 2020 study included particle numbers and totals at a variety of indoor locations, including 19 commercial flights, boarding processes, taxiing, mountaineering, and cruising, measured across departure and arrival terminals. It included monitoring both masses. , Descent, and unplanned.

Since monitoring could not identify the particle type, it is not possible to directly measure the risk of coronavirus exposure.

“I wanted to emphasize how important high ventilation and clean air supply are to reduce particle concentration in indoor spaces,” said Nga Lee (Sally) Ng, associate professor and Tanner Faculty Fellow of the Faculty of Chemistry. Said. Faculty of Biomolecular Engineering and Geo-Atmospheric Sciences, Georgia Institute of Technology. “The particle mass and particle number concentration in the cabin was the lowest.”

This study is believed to be the first study to measure both the mass and number of sized particles in a commercial flight from terminal to terminal, and a wide range of indoor spaces was published in the journal. Indoor air I posted it online on the journal’s website.

With the support of Delta Air Lines, this study could be the first study to comprehensively measure the particle concentrations that passengers from terminal to terminal may encounter.

As scientists learn more about coronavirus infections, aerosol particles are being focused on as an important source of the virus spreading indoors. Infected people can spread the virus when breathing, talking, or coughing, producing particles smaller than 1 micron (one millionth of a meter) to 1,000 microns in size. Large particles quickly fall out of the air, while small particles remain floating.

“These particles can float in the air for extended periods of time, especially in poorly ventilated areas, and can travel to every corner of the room,” Ng said. “If they are viral particles, they can infect people who may be at a considerable distance from the person who releases the particles.”

To better understand the circulation of airborne particles, Delta approached Ng and conducted studies of multiple indoor environments with an emphasis on air travel conditions.

Researchers at the Georgia Institute of Technology use handheld devices that can measure the total number of particles and their mass to determine the air quality of a range of restaurants, stores, offices, homes, and vehicles in the Atlanta region, including buses, trains, and private cars. I investigated.

They trained Delta staff to make the same type of measurements on terminals, boarding areas, and various aircraft throughout all stages of flight. Delta staff recorded their position as they moved through the terminal, and the instrument generated measurements that matched the restaurants and stores that passed on the way to and from the boarding and departure gates.

“Measurements began as soon as we stepped into the departure terminal,” Ng said. “We were thinking about the whole trip, that is, people encountering terminals from terminal to terminal.”

During flight, aircraft air is changed 10 to 30 times an hour. Some aircraft only take in outside air at cruising altitudes, where there are few pollutant particles found in the air near the ground. Another aircraft mixes the outside air with recirculated air that passes through a HEPA filter, removing more than 99% of the particles.

In total, the researchers evaluated measurements from 19 commercial flights with a passenger load of about 50%. The flights were a mix of short and medium range flights, including the CRJ-200 and aircraft from A220 to 757, A321 and 737.

Of all the spaces measured, the restaurant had the highest particle levels because it was cooked there. This was followed by stores, followed by vehicles, homes and offices. For example, the average particle number concentration of submicrons measured in restaurants was 29,400 particles per cubic centimeter, and in the office it was 2,473 particles per cubic centimeter.

There is a very comprehensive dataset for investigating the size distribution of particles across these different spaces. Now you can compare the indoor air quality of different spaces. “

Nga Lee (Sally) Ng, Associate Professor, Faculty of Chemistry and Biomolecular Engineering, Faculty of Earth and Atmospheric Sciences, Georgia Institute of Technology and Tanner Faculty Fellow

Due to the mobile device used, researchers were unable to identify the source of the particles. It may have included both biological and non-biological sources. “Further research could include direct measurement of viral load and tracking of particle movement in indoor space,” she added.

Jonathan Litzenberger, managing director of Delta’s Global Cleanliness Strategy, said the study will help advance the company’s goal of protecting customers and employees.

“Keeping the air in flight clean and safe is one of the most basic layers of protection that Delta aims to provide to its customers and employees,” he said. “We are always working to better understand the travel environment and ensure that the measures we are implementing are working.”

Overall, this study emphasizes the importance of improving indoor air quality as a means of reducing coronavirus infection.

“Whether you’re in the office or on an aircraft, higher ventilation and better particle filtration are the keys to lowering your total particle concentration,” says Ng. “This should also reduce the concentration of virus particles that may be present.”