American Airlines touts a new tool to combat COVID. But does it really make flying safer?

American Airlines is adding an innovative new Covid protection to its planes. But worry is still in the air Better disinfection of surfaces reduces one risk. But air quality is a bigger worry. Fortune

American Airlines announced federal approval of a new disinfectant that the airline says it will use on some flights to improve protection against surface transmission of the coronavirus. The product will be integrated into what American calls its Clean Commitment, an effort to keep its planes safe enough to draw back travelers.

But the evolving science on COVID-19 points to ongoing uncertainty about whether it’s safe to fly—and about the airline industry’s broader prospects.

The new approval by the U.S. Environmental Protection Agency is for a product called SurfaceWise2, produced by Dallas-based Allied BioScience. The disinfectant will be applied using electrostatic sprayers, which add an electromagnetic charge to particles of cleaner, making them better adhere to surfaces. Electrostatic disinfectant spraying is already widely used by airlines, including American competitors Southwest and Delta.

The key difference is that SurfaceWise2 is effective for up to a week with a single application. That may be as much of a boon to labor efficiency as safety. Existing disinfectant sprays are similarly effective, but are applied by airline staff after every flight. ...

But the EPA approval, issued on an emergency exemption basis, is quite limited. For one year, the product can be used by American Airlines flights that pass through airports in Texas, and by two physical therapy clinics operated in Texas by Total Orthopedics Sports & Spine. Speaking to the press today, EPA chief Andrew Wheeler said other entities that want to use the product may apply separately for an emergency exemption via their state authorities....

Better surface disinfection, however, increasingly pales next to worries about air quality on passenger flights. There is now strong scientific consensus that COVID-19 is primarily spread by direct social contact, with surface transmission playing a smaller role. ...

...most airliners are considerably safer than eating indoors in a restaurant. American says that on all planes in its fleet, air is either replaced with outside air, or scrubbed using hospital-grade HEPA filtration, every two-to-four minutes. That’s nearly twice the average replacement rate in an office building. ...

Nonetheless, there is clear evidence of airborne transmission risk on passenger flights. A 2003 study of the transmission of the SARS coronavirus on a passenger plane found that a single symptomatic person spread the virus throughout the cabin of the plane, infecting as many as 22 others. More recently, a study of COVID-19 transmission on a March 2020 international flight found possible transmission at a distance of up to two rows. ...