Airborne Pathogens: Elusive and Dangerous Part 1

Michelle Beaver
10/13/2008

The study of airborne pathogens is complex, but people of every education level know that air quality is important, and that germs let loose in the air can lead to infection of millions of people. Indeed, th

e issue of air quality and safety is widespread, says Jeffrey Cirillo, PhD, associate professor in the Department of Microbial and Molecular Pathogenesis at Texas A&M University System Health Science Center.

“I believe that the average person is aware of the importance of air quality because it is an issue that everyone discusses on a daily basis — smog reports, environmental protection, infections in air,” Cirillo sai

d. “In my discussions with people it seems clear that everyone understands that if you can’t breathe, you are in trouble.”

The threat of air

borne pathogens should be taken “very seriously” because air is the most efficient route by which pathogens can gain access to a large number of people, according to Cirillo. “Epidemic-causing pathogens can often spread by the airborne route for just this reason and efficiency of transmission is one of the most important characteristics that should be considered when evaluating how large an impact infectious diseases can have,” he adds.

One of the primary tools to prevent the spread of airborne pathogens in healthcare facilities is the use of negative air pressure. Negative air pressure regulates environments. By using a negative pr

essure containment field, such as a portable anteroom, healthcare staffs can prevent harmful pathogens from escaping an airborne infection isolation room, or from ceiling cavities during maintenance work, says John Pierson, product manager for Fiberlock Technologies. “This ability is critical in the event of a sudden influx or surge of patients,” Pierson says. “In fact, the federal government uses the ability of a facility to deal with a surge of patients as one criterion for Health Resources and Services Administration funding.”

Disastrous Proportions

Determining which airborne pathogens are most likely to cause a pandemic event is no easy feat.

“The great unknown is the issue here,” Pierson says. “We truly don’t know what pathogens are more likely to be the cause of a biological disaster. Experts are currently looking at H5N1 very closely as a candidate for pandemic due several of its genetic traits, but the threat of biological agents such as smallpox, anthrax and botulinum being used as weapons complicate the matter.

“There is the possibility that a genetically altered organism used for bio-terror could dramatically alter the playing field in regards to treatment and prevention,” he adds. “The reality could be that a large number of people could, without warning, need to be hospitalized and isolated from other patients. Regardless of the organism, airborne infection isolation would be essential to preventing the spread of disease during this type of event.”

Use of personal protective equipment (PPE) helps reduce the spread of pathogens, and is even more important than usual in a disastrous event. However, PPE is not the end all be all, according to Jeffrey Birkner PhD, CIH, vice president of technical services for Moldex-Metric, Inc.

“Addressing pandemic and emergency airborne pathogen threat response issues must be all encompassing and does not only deal with PPE,” Birkner says. “In addition, administrative and engineering controls must be considered first. PPE, while extremely important, is actually the medical facility’s and staff’s last line of defense to an airborne pathogen threat.”

Two of the major concerns regarding emergency preparedness for a pandemic event include a facility’s surge and isolation capacity, says Gary Messina, principal and CEO of Biological Controls. Messina has more than 30 years experience in the field of high-efficiency filtration and design and manufacture of airborne infection control equipment.

“The Centers for Disease Control and Prevention recommends that hospitals establish isolation rooms maintained under negative pressure,” Messina says. “But most hospitals have a tiny fraction of isolation rooms available compared to the total room count. And at any one time these rooms may already be occupied, which further reduces the availability to isolate individuals entering through the surge. Since many hospitals operate at near capacity levels currently, the addition of undiagnosed patients arriving for treatment in a disaster event poses the question of accommodating a huge surge of individuals requiring both beds and isolation areas. This does not take into account the regular patient load seen everyday at every hospital and medical facility.”

That’s not a pretty picture, but it’s one for which every facility must prepare. Another threat related to airborne pathogens is mold, especially during and after certain disasters, such as floods or hurricanes. In humid areas mold can be a “huge concern” says Grant Rowe, respiratory protection product manager for Bullard.

“The good news is that airborne precautions and contact precautions are very effective regardless of the specific pathogen,” Rowe says. “It is important to understand that some infections can enter in through the eyes (such as mold) and an N-95 mask will not be sufficient; tight fitting goggles, a full face respirator, or a PAPR (powered air purifying respirators) with a loose fitting face piece or hood would be more appropriate in these situations.”

Prevention and Containment

As the old saying goes, an ounce of prevention is worth a pound of cure. In order to prevent airborne pathogen transmission — especially influenza — healthcare staffs should ask and seek answers to certain questions, especially regarding influenza, says Edward Fries, a spokesperson for the NIOSH National Personal Protective Technology Laboratory, which is part of the National Institute for Occupational Safety and Health (NIOSH).

These questions include:

What are the major modes of influenza transmission?

What are the relevant sizes of aerosols?

What is the infectivity of aerosols?

How does air flow exchange and ventilation affect transmission?

What is the effectiveness of medical masks?

What is the role of fomites?

Should PPE other than respirators be certified? If so, who would be responsible for certification?

Read more in part 2 Click Here

Air Purification Product with RCI Technology