Aircraft cables may have the lowest levels of aerosol particles, a study showed

If you are looking for an indoor space with a low level of air pollution, a commercial aircraft flying at altitude may be your best option.

A new study of air quality in indoor spaces such as stores, restaurants, offices, public transportation – and commercial jets – shows aircraft booths with the lowest levels of tiny aerosol particles.

Conducted in July 2020, the study involved monitoring both the number of grains and their total mass over a wide range of indoor spaces, including included 19 commercial flights that were measured across departure and arrival points, process of boarding, taxiing, climbing, sailing. , descent, and descent.

The study was unable to identify the types of granules and therefore does not provide a direct measure of the risk of coronavirus exposure.

“We wanted to emphasize the importance of having a high level of ventilation and a supply of clean air to reduce grain density in indoor spaces,” said Nga Lee (Sally) Ng, co-professor associate and Tanner Faculty Fellow in the School of Chemistry and Biomolecular Engineering and the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. “

This study is considered to be the first to measure both the size and volume of commercial aircraft from premises to destination and a wide range of indoor spaces were accepted for publication in the journal. Indoor air and posted online on the magazine’s website.

Supported by Delta Air Lines, this research may be the first to make a complete measurement of clusters of grains that are likely to occur with passengers from destination to destination.

As scientists learn more about the spread of the coronavirus, the focus has turned to aerosol granules as an important source of internal viral transmission. Infected people can spread the virus while breathing, talking, or coughing, forming particles ranging in size from less than a micron – one million meters – to 1,000 microns. The largest pieces fall from the sky quickly, but the smallest ones are still hanging.

“Especially in poorly ventilated areas, these grains can be defrosted in the air for a long time, and can travel to all corners of space,” Ng said. “If they are viral granules, they can infect people who may be at a great distance from a person who releases the granules.”

To better understand the circulation of airborne particles, Delta asked Ng to study a number of indoor environments, with a strong focus on air travel conditions.

Using hand-held instruments capable of measuring the total number of grains and their mass, Georgia Tech researchers studied air quality in a series of Atlanta-area restaurants, stores, offices, homes, and vehicles – including buses, trains, and private cars.

They trained Delta staff to perform the same measurements in terminals, accommodations and different flights through all stages of flight. Delta staff recorded their locations as they moved through the destinations, and the instruments measured according to the restaurants and stores they made their way to and from gates. boards and leaving.

“The measurements started as soon as they entered the exit center,” Ng said. “We were thinking about the whole trip, what one would encounter from a building to a destination.”

On the flight, airstrikes are exchanged between 10 and 30 hours per hour. Some planes incorporate outdoor air, which at the height of trips is largely free of pollutants found in the air near the ground. Another aircraft mixes outdoor air with recirculated air that passes through HEPA filters, which remove more than 99% of grains.

In total, the researchers evaluated measurements from 19 commercial aircraft with passenger loads of around 50%. The flights included a combination of short and medium flights, and flights between the CRJ-200 and A220 to the 757, A321, and 737.

Among the places measured, the highest levels of cereals in restaurants were due to cooking being done there. There were stores next door, and then vehicles, homes and offices. The average density of submicron grains measured in restaurants, for example, was 29,400 particles per cubic centimeter, and in offices, it was 2,473 per cubic centimeter.

We have a very extensive data set to look at the grain size distribution across these different locations. We can now compare indoor air quality in a number of different places. “

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

Due to the portable instruments used, the researchers were unable to determine the source of the grains, which could be included in both biological and non-biological sources. biological. “Further studies may involve direct measurement of viral loads and detection of particle movements in indoor locations,” she said.

Jonathan Litzenberger, Delta’s managing director of Global Cleanliness Strategy, said the research helps advance the company’s goals of protecting its customers and employees.

“Keeping the air clean and safe at the time of flight is one of the most fundamental safeguards that Delta aims to provide to our customers and employees,” he said. “We are always working to better understand the travel environment and ensure that the measures we are implementing work. “

Overall, the study highlights the importance of improving indoor air quality as a means of reducing coronavirus transmission.

“Whether you are in an office or in an airplane, the key has a higher ventilation rate and good filtration of the grain granules to reduce the overall grain density,” Ng said. “That should also reduce the amount of any virus that may be present.”