Why Flying Makes You Ill

CLEANING AIRCRAFT AIR WOULD MAKE FLYING A LOT SAFER AND HEALTHIER IN COMMERICIAL JETS.

*We draw today from The Economist, Sept. 19th-25th, 2009 Edition.

One of the common and most pervasive concerns of passengers on commerical jets is the fact that many become ill during the flight. No matter what airlines tell you, having a large group of people couped up in a relatively small area for an amount of time increases the risk of catching an infection.

Viral diseases like Swine Flu have spread quickly around the world because of air travel. There are also pollutants to worry about such as engine fumes leaking into the passenger compartment.

A new developement could help ease this situation and help passengers and crew breathe more easily. Just this week (Sept. 19, 2009), two British firm; BAE Systems (a defense and Aerospace giant) and Quest International (a small producerof equipment used to sanitise the air in hospitals and nursing homes) have announced that they had successfully adapted Quest's technology for use in aircraft. They made this bold claim on behalf of their new company, called AirManager. Uniquely, it can be retro-fitted during a routine overnight service and uses less power than a light bulb, but is capable of zapping just about all the bacteria, viruses and other biohazards in cabin air, as well as destroying chemical contaminants and pollutants. And it kills nasty smells as well.

Basic Air Flow:
Air has to be pumped into the fuselage of an aircraft once it flies above 3000 meters (9,800 feet) because from there the air outside starts to become thin with too little oxygen to keep people alive. In the early days of commercial flight, when piston engines turned propellars, electrical generators were used to provied the power to pressurise the cabin. But with the arrival of faster, higher flying jets, aircraft makers found it more efficient to pressurise the fuselage by "bleeding" some of the air entering the compressor stage of the actual jet turbine (before it was mixed with fuel of course). At first, only fresh air was taken from the engines, but as jets have become more fuel efficient, air bled from the engine has been mixed with recycled air from the cabin. Why? Because the big fans mounted on modern "high bypass" jet engines achieve thrust more efficiently by sending a larger volume of air around the turbine as opposed to through the turbine. Thus, with less air now available in the compressor, any that is bled off means the turbine has to work harder, which in turn only adds to precious fuel consumption. A compromise was reached: a 50:50 mixture of fresh and recirculated cabin air is used although pilots can reduce the amount of fresh air to save fuel.

Mixture:
The mixed air is maintained in the cabin at a pressure which is equal to an altitude of 2,500 meters and is passed through the well known HEPA filters. (high efficiency particulate arrest) Provided they are cleaned regularly, and that is a big "IF", HEPA filters can grab a sizeable amount of microscopic particles. Still, some nasties get through.

Clean The Air:
The new AirManager system is said to kill 99.999% of all pathogens in a single pass. Even on a short flight, the cabin air will pass through the filters around 30 times. Quest says the mechanism is a non-thermal plasma using a high voltage screen to strip electrons from some of the molecules in a gas. The plasma is confined using an electric field grid and the cabin air is passed through this. The free electrons disrupt the molecular bonds of any particles in the air, causing them to break up into electrically charged pieces. A second electrically charged filter trap grabs these pieces like fly paper.

Cost:
Each unit costs $16,000. Not too bad but the bigger the plane, the more of these gadgets are needed. Still, in the long run, it would be worth the passenger comfort and health to install these small, energy efficient cleaners. They would all pay for themselves in a year by reducing the air that has to be bled from the turbines;  thus letting the new engines work as designed for maximum fuel efficiency.
_______________________________________________________________________

Middle Seat: Where Germs Lurk on Planes
Discover what to do when stuck at 30,000 feet next to sneezers and coughers.

By Scott McCartney, The Wall Street Journal

It's a common complaint: Fly on a crowded plane and come home with a cold. What's in the air up there?
 
Air travelers suffer higher rates of disease infection, research has shown. One study pegged the increased risk for catching a cold as high as 20 percent. And the holidays are a particularly infectious time of year, with planes packed full of families with all their presents — and all those germs.
 
Air that is recirculated throughout the cabin is most often blamed. But studies have shown that high-efficiency particulate air (HEPA) filters on most jets today can capture 99.97 percent of bacterial and virus-carrying particles. That said, when air circulation is shut down, which sometimes happens during long waits on the ground or for short periods when passengers are boarding or exiting, infections can spread like wildfire.
 
Flu transmitted to 54 passengers
 
One well-known study in 1979 found that when a plane sat three hours with its engines off and no air circulating, 72 percent of the 54 people on board got sick within two days. The flu strain they had was traced to one passenger. For that reason, the Federal Aviation Administration issued an advisory in 2003 to airlines saying that passengers should be removed from planes within 30 minutes if there's no air circulation, but compliance isn't mandatory.
 
Much of the danger comes from the mouths, noses and hands of passengers sitting nearby. The hot zone for exposure is generally two seats beside, in front of and behind you, according to a study in July in the journal Emerging Infectious Diseases, published by the U.S. Centers for Disease Control and Prevention.
 
A number of factors increase the odds of bringing home a souvenir cough and runny nose. For one, the environment at 30,000 feet enables easier spread of disease. Air in airplanes is extremely dry, and viruses tend to thrive in low-humidity conditions. When mucous membranes dry out, they are far less effective at blocking infection. High altitudes can tire the body, and fatigue plays a role in making people more susceptible to catching colds, too.
 
Also, viruses and bacteria can live for hours on some surfaces — some viral particles have been found to be active up to a day in certain places. Tray tables can be contaminated, and seat-back pockets, which get stuffed with used tissues, soiled napkins and trash, can be particularly skuzzy. It's also difficult to know what germs are lurking in an airline's pillows and blankets.

Page 2 of 2
Middle Seat: Where Germs Lurk on Planes (continued)
Research has shown how easily disease can spread. Tracing influenza transmission on long-haul flights in 2009 with passengers infected with the H1N1 flu strain, Australian researchers found that 2 percent of passengers had the disease during the flight and 5 percent came down within a week after landing. Coach-cabin passengers were at a 3.6 percent increased risk of contracting H1N1 if they sat within two rows of someone who had symptoms in-flight. That increased risk for post-flight disease doubled to 7.7 percent for passengers seated in a two-seat hot zone.
 
The epidemic of severe acute respiratory syndrome (SARS) in 2002-03 suggested a wider exposure zone, however. On one flight studied, one passenger spread a particular strain to someone seated seven rows away, while people seated next to the ill passenger didn't contract the disease.
 
That said, most people sitting near someone who is ill probably won't get sick. "When you get aboard an aircraft, most of us don't have a say on who we sit next to. But that doesn't doom you to catching the flu," said Mark Gendreau of Boston's Lahey Clinic Medical Center.
 
In 2005, he was part of a team that published a paper in the Lancet that concluded the perceived risk for travelers was higher than the actual risk, and that's still the case today, he said.
 
Steps to prevention:
 
Even so, there are some basic precautions passengers can take to keep coughs away.
 
>Hydrate. Drinking water and keeping nasal passages moist with a saline spray can reduce your risk of infection.
 
>Clean your hands frequently with an alcohol-based hand sanitizer. We often infect ourselves, touching mouth, nose or eyes with our own hands that have picked up something.
 
>Use a disinfecting wipe to clean off tray tables before using.
 
>Avoid seat-back pockets.
 
>Open your air vent and aim it so it passes just in front of your face. Filtered airplane air can help direct airborne contagions away from you.
 
>Change seats if you end up near a cougher, sneezer or someone who looks feverish. That may not be possible on very full flights, but worth a try. One sneeze can produce up to 30,000 droplets that can be propelled as far as six feet.
 
>Raise concerns with the crew if air circulation is shut off for an extended period.
Avoid airline pillows and blankets (if you find them).
 
"If you take the proper precautions, you should do quite well," said Dr. Gendreau. "In most of us, our immune system does what it was designed to do — protect us from infectious insults."
 
Hidden dangers in security:
 
You think the plane is bad? Security checkpoints harbor a host of hazards as well, researchers say.
 
People get bunched up in lines, where there is plenty of coughing and sneezing. Shoes are removed and placed with other belongings into plastic security bins, which typically don't get cleaned after they go through the scanner. A National Academy of Sciences panel is six months into a two-year study that is taking samples at airport areas to try to pinpoint opportunities for infection. With limited resources, airports and airlines have asked researchers to help figure out where best to target prevention, said Dr. Mark Gendreau of Boston's Lahey Clinic Medical Center who is on the panel.
 
Check-in kiosks and baggage areas are other prime suspects in addition to security lines, he said.

 

Dr. Haberstroh is a Somerville and Boston Chiropractor.