Last Year, Expert Panel Recommended Standards; Industry Has Yet to Act
By Scott MCCARTNEY
Airline customer service isn’t the only thing in need of improvement these days. The air in airplane cabins needs some fixing, too, and not just because your seatmate sneezed all over you.
A year ago, a blue-ribbon panel of experts across the aviation industry recommended voluntary standards for onboard air circulation, lower ozone exposure, new monitoring for contaminated air from oil or hydraulic fluid leaks, and limits on pesticides used on planes.
But aviation regulators and airlines have yet to act. “It’s frustrating because these issues are important for crew members and for passengers, and should have been addressed a long time ago,” says Judith Murawski, a cabin air quality expert for the Association of Flight Attendants.
The Ashrae committee, which included representatives from aircraft and equipment manufacturers, airlines, labor groups and even passengers’ advocates, found that air quality and current regulatory standards are basically adequate, but called for improvements.
“In general the air on an airplane is not too bad, but when things go wrong, they can get really bad. And it happens in a hurry,” says Byron W. Jones, the committee’s chair and associate dean at the College of Engineering at Kansas State University. Dr. Jones and other Ashrae committee members describe the response from regulators to the new standards as “fairly muted” so far.
An FAA spokeswoman says the agency is awaiting the results of other research before taking action on air quality. Nothing is imminent, she says.
Air quality on planes is often worst when the plane is on the ground. Air circulation systems sometimes aren’t operated while passengers board, for example, or when planes sit for long ground delays. Problems can develop quickly. In some famously long delays, when planes have sat stranded for several hours, passengers have complained of hot, stuffy cabins with inadequate air-conditioning.
“If you have it off even five minutes, you start to build up contaminants in aircraft,” Dr. Jones says.
Recommendations to improve airplane cabin air quality:
- Run air circulation all the time, including during boarding and ground delays.
- Tighten up on pesticide use on planes.
- Control temperatures to avoid sweltering cabins.
- Strengthen ozoneconcentration limits.
- Monitor air from engine compressors for contaminants.
The Ashrae group said the industry needs temperature limits so that cabins don’t become sweltering on the ground on hot days. Its standards say that air circulation should never be shut down on a plane with people aboard except for operational reasons like de-icing so toxic fumes aren’t sucked in, and that an absolute limit of 30 minutes without air circulation should be imposed.
The FAA says it issued an advisory to airlines in 2003 recommending that passengers be removed from planes no more than 30 minutes after air circulation equipment is shut down, but the limit isn’t mandatory.
Airlines and manufacturers long argued that because air is moved quickly in cabins and scrubbed through HEPA filters, which can catch 99.9% of pathogens including viruses, airplane air is healthier than in office buildings or other public spaces.
But the volume of air that circulates per person is higher in office buildings. Anecdotal reports of illnesses among passengers and flight attendants over the years have often sparked fears that cabin air could be hazardous. In addition, half the air circulated through a jet is drawn from the outside; half is re-circulated, leading to concerns.
When diseases are spread onboard airplanes, they are passed by proximity, not circulation systems, experts say. When passengers cough or sneeze, they potentially infect nearby passengers, but viruses and bacterium aren’t spread through an entire plane. Because air circulation rates are high, bad stuff gets flushed out quickly.
“If you’re sitting on a trans-ocean flight next to someone who is contagious, odds are pretty high you’re going to be exposed,” Dr. Jones says. “There’s nothing particularly unique about an airplane. It’s just a factor of close quarters.”
Of course, sometimes sick passengers move up and down the aisles, potentially increasing exposure. And public health officials are often concerned with airplanes as transporters of disease, carrying sick people from one continent to another.
Aircraft air circulates across seat rows, not down the length of the plane. Current requirements look at air volume as an average throughout an airplane. But the Ashrae committee was convinced that some parts of the cabin may not be getting the air needed, such as flight crew areas. The new standard, which applies to any passenger commercial airplane capable of carrying 20 passengers or more, recommends looking at air volume on a zone-by-zone basis and would require air outlets in all crew work stations.
Flight attendant unions, which have long voiced fears about illnesses that may have resulted from exposure to poor air aboard airplanes, had been pushing for a tougher air-circulation requirement, but are overall pleased with the Ashrae report.
“It’s a big step forward. It’s not perfect, but it’s something everyone can accept,” says Ms. Murawski, an industrial hygienist for the union who was a member of the committee.
Despite the diversity of the committee, the final recommendations were unanimously approved. Standards include new protections on pesticide use, a big concern to flight attendants. More than 40 countries require disinfecting planes, some with pesticides banned by the Environmental Protection Agency.
Ozone in cabin air was another concern. Air drawn from outside can contain high ozone levels because it comes from the upper atmosphere. Many aircraft, particularly long-haul jets, have “ozone converters” that decompose ozone before it’s fed into cabins, but Dr. Jones says a lot of aircraft, mostly planes that fly only short hops, still fly without ozone converters.
The new standard sets a maximum level of ozone contamination and requires converters on planes that fly where ozone is expected to be encountered.
The new standard would also require sensors to ensure that fresh air drawn from the outside and compressed inside engines is not contaminated by an oil leak or a hydraulic fluid leak. Regulators say contamination of “bleed air,’’ drawn from engines compressors for several uses including pressurizing the cabin, is rare, but studies continue to look for a health risk.
The FAA says that no sensors yet exist that could do the job, and that more study is needed. The U.S. House of Representatives recently passed legislation including a provision for development of bleed-air sensors.
In March, Ashrae wrote to the FAA and European Aviation Safety Agency asking for an investigation into this issue. The FAA responded saying it was studying the Ashrae report and waiting for results of other research; the European agency said the frequency of contamination reports was low and “the consequences during these events are generally of limited severity.”
“We consider it necessary to collect additional factual evidence of the safety implications,” Patrick Goudou, executive director of the European agency, said in a letter to Ashrae.