Studies indicate that most jets today can capture 99.97% of bacterial and virus-carrying particles. It's when the air circulation is shut down which happens during long waits on the ground or when passengers are boarding or exiting is when infections can spread.
The report points out a study in 1979 that when a plane sat three hours with the engines off and no air circulating, 72% of 54 people on board go sick within two days. It was traced to one passenger who had the flu virus. In 2003 the Federal Aviation Administration issued an advisory that passengers should be removed from planes within 30 minutes if there's no air circulation but compliance is not required.
One thing passengers should be aware of are the "hot zones": beware of sick passengers who are two seats beside, in front of and behind you. But passengers should note that other factors come into play. The environment at 30,000 feet is extremely dry and because viruses tend to thrive in low-humidity conditions they can spread easier. The mucous membranes of people are not as effective in blocking infection when they are dry. In addition the body can tire at higher altitudes making passengers more susceptible to catching colds.
Germs can live for hours on airplane cabin surfaces. Everything from tray tables, seat-back pockets, pillows, blankets, latches, overhead bins and the lavatory can be contaminated.
The report suggests passengers take these precautions to keep germs at bay:
Hydrate - Drink water and keep nasal passengers moist with a saline spray.
Clean Your Hands - Use an alcohol-based hand sanitizer frequently. Passengers often infect themselves by touching their mouth, nose or eyes.
Disinfecting Wipes - Use them to clean off tray tables before using.
Seat-Back Pockets - Avoid them. They get stuffed with used tissues, soiled napkins and trash.
Open Your Air Vent - Aim it so that air passes just in front of your face so the filtered air can direct airborne contagions away from you.
Change Seats - If you are seated near a cougher, sneezer or someone who looks like they may have a fever, changing seats may not be possible on full flights but it is worth a try. One sneeze can produce up to 30,000 droplets that be propelled as far as six feet.
Air Circulation - Notify the flight crew if the air is shut off for an extended period.
Pillows and Blankets - Avoid them.
Click HERE to view the complete article on wsj.com. The graphic below can also be viewed in the article or click on the graphic for a larger view.