Saturday, April 25, 2009

Air Purification at Herbie's

Herbie's has the same Merv 17 HEPA and HEGA air purification recommended by homeland security experts, including the U.S. military and the National Institute for Occupational Safety and Health, to protect the public from biological warfare:

HEPA filtration (high-efficiency particulate arrestor or arrestance air filter). HEPA is used for control of solid particulate matter, such as respirable spores, bacteria, or radioactive particles. These filters are widely used in cleanrooms, hospital operating rooms, and pharmaceutical and electronic manufacturing.

HEPA’s removal efficiency is 99.97% of particles larger than 0.3 microns. At the time of their development in World War II, this was considered to be the most penetrating particle size. However, it is now known that this size constraint is closer to 0.2 microns, meaning that filter efficiency increases on either side of the size band. This efficiency level is comparable to a MERV 17 designation (Minimum Efficiency Reporting Value as determined by ANSI/ASHRAE Standard 52.2-1999, Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size). Versions of the filter are available with even higher efficiencies, up to 99.999%—a MERV 20 designation.

HEGA air cleaning (high-efficiency gaseous adsorber). HEGA is for chemical molecular control, such as toxic industrial chemicals (TICs) or war gases. The HEGA uses a specially treated carbon called ASZM-TEDA that is designed to control designated war gases (the acronym indicates the reagents used to treat the carbon). Chemical filters using other containment configurations and other sorbents, such as untreated carbon, permanganate treated alumina, or blends of sorbents are used for odor control, pollution control, and industrial applications. Both technologies were derived from work in WWII for the containment of radioactive iodine around nuclear reactors."

The CDC relies on the same air filtration found at Herbies to strip the air of influenza:

"The appropriate use of engineering controls and other control efforts will require frequent analysis of pandemic influenza transmission patterns in designated wards, in the facility, and in the community.

If possible, and when practical, use of an airborne infection isolation room may be considered when conducting aerosol-generating procedures. Airborne infection isolation rooms receive numerous air changes per hour and are under negative pressure, so that the direction of the air flow is from the outside adjacent space (e.g., the corridor) into the room. The air in an airborne infection isolation room is preferably exhausted to the outside, but may be recirculated provided that the return air is filtered through a high-efficiency particulate air (HEPA) filter."