So what are you supposed to believe? Suddenly, there are dozens of companies offering protection from biological contaminants since the anthrax scare. Which one is the most effective? What should you look for to protect workers? Are gloves and masks enough? Let's look at what's available in equipment and also look at a system of procedures recommended by the government and industry experts for handling potentially contaminated mail.
What is of particular concern is the potential for biological threats that can be loaded into an envelope or box and sent to a targeted victim. Unfortunately, there are dozens of workers between the source and the intended victim who can be affected by the parcel. There is a long road from the mailbox of the sender to the mailbox of the receiver. The mail is dumped, spread, sorted, transferred, barcoded, scanned, resorted, piled and boxed for delivery, and then it may go through the same process again only this time in a corporate environment. Some of this process is automated, but there are still many people who keep the flow moving.
Protective Equipment
If we look at the process, we see that no one piece of equipment can completely solve the issues at each stage. Biological hazards can come in many forms. A High Efficiency Particle Air (HEPA) filtered, negative-pressure glovebox that isolates the mail from the user is very effective, if correctly designed, for catching and keeping the organism in a contained environment until it is removed by experts. HEPA filtration was developed over 40 years ago to trap extremely small particles, 99.97% of particles down to 0.3 microns, in fact. A single strand of your hair is about 59 microns in diameter, so you can imagine how small a third of a micron is. Anthrax spores are generally regarded to be in the one to five micron range, and a HEPA filter will trap 99.99% of those particles. When combined with neoprene gauntlet-style gloves, the user has a much higher degree of protection from inhaled or contagious anthrax infection.
What about larger spaces like the mail center itself? There are products that have been developed for hospital isolation rooms that also depend upon HEPA filtration. Rooms are usually put under negative pressure (slight vacuum) from the surrounding rooms so whatever is inside stays inside.
The reverse is used when you want to get away from biological contamination outside to a "safe room." HEPA-filtered air is pumped into a room under a slight positive · pressure so that a constant flow of clean air is always in the room and airborne contaminants can't get into it under normal circumstances. Workers can go into the positive-pressure room for protection until the threat passes. This method can be applied to conference rooms, gymnasiums and all the way up to entire buildings.
When the size of the protected space gets very large, there must be multiple HEPA filters to handle the amount of air to be filtered. When the situation calls for it, a design called a Bag-In-Bag-Out (BIBO) filter housing is used. This is a stainless steel housing with seals that are leak-proof that holds the filters while they do their work. These are typically used in hospitals, nuclear power plants, silicon wafer manufacturing and other critical-function locations that depend upon pure air. The military typically uses them to filter airborne biological and nuclear contamination in command centers and in areas of conflict.
Other Technologies
There are other technologies that have been developed to protect the air from biological threats. These technologies incinerate a varying amount of the micro-organisms with very intense heat, using thermo-catalytic oxidation (TCO) or ultraviolet (UV) lights to destroy the cell structure of the living organisms. Although these technologies have their place, they are generally not as efficient as HEPA filtration since they don't actually remove the leftover particulate from the air.
To ensure effective removal of micro-organisms, the CDC recommends a room's air be changed at least 12 times per hour. This can be a challenge as the amount of air increases and requires air-handling equipment that eventually gets large enough to need to be placed outside of a building, usually on the roof or besides the building. The rate of air movement works to drastically reduce the benefits of UV lights and TCO since they both depend on prolonged contact with the organisms to be effective.
Recommended Mail Handling Procedures
Since September 11, the Postal Service and other U.S. government agencies have released information about increasing the safety of handling mail through the use of enhanced procedures. They bear repeating and should be posted in any mail-handling area. These and more guidelines are available from the Postal Service in Publication 166, issued in April 2002.
Tom Day is product manager of New Market/Product Development for AAF International in Louisville, Kentucky. Contact him at 502-637-0487, Fax: 502-637-0351 or by e-mail at tday@aafintl.com. For additional information on AAF International, please call 800-477-1214 or visit them on the Web at www.aafintl.com.
