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| BULLETIN VP JOE BIDEN, TARED UNFAIRLY BY US PRESS |
You owe the Vice President an apology, copies sent to Rahm Emanuel. VP Joe Biden, BBC.
www.ceei-news.org www.ceei-climate.org Species www.esew.org Streams www.apsrs.org www.eco-pedia.org
CEEI
Center for Environmental Education and Information, a 50lc3 founded in 1990 at the Hemingway Learning Institute, P.O. Box 1778, Sun Valley, Idaho 83353, fax and phone 208-578-1557, email ceei@cox.net. (All rights reserved.) Purpose: to make current information on the status of the environment / climate available to every classroom.
From: Max Casebeau
Date: May 2, 2009 3:13:22 AM MDT
To: Rahm , worldservice@bbc.co.ok
Cc: Rahm , Fred burmester
Subject: COPY PRESIDENT OBAMA , VP BIDEN, RAHN EMANUEL. ROBERT GIBBS.
Reply-To: Max Casebeau
You owe the Vice President an apology, copies sent to Rahm Emanuel. VP Joe Biden, BBC.
www.ceei-news.org www.ceei-climate.org Species www.esew.org Streams www.apsrs.org www.eco-pedia.org
CEEI
Center for Environmental Education and Information, a 50lc3 founded in 1990 at the Hemingway Learning Institute, P.O. Box 1778, Sun Valley, Idaho 83353, fax and phone 208-578-1557, email ceei@cox.net. (All rights reserved.) Purpose: to make current information on the status of the environment / climate available to every classroom.
Excerpts From FSF Cabin Air Study
[The following is excerpted from a Flight Safety Foundation study on the risk of Tuberculosis transmission aboard aircraft. It, quite necessarily, goes into great detail as to the quality of cabin air and how that may affect such transmissions. All emphasis has been supplied by the editor of http://AirlineSafety.Com. To read the entire study (Adobe Acrobat .pdf file), go to: Entire Study.�Ed. ASC]
F L I G H T S A F E T Y F O U N DAT I O N
Vol. 33 No. 4�5 For Everyone Concerned with the Safety of Flight July�October 1998
CABIN CREW SAFETY
Guidelines Enable Health Authorities to Assess Risk Of Tuberculosis Transmission Aboard Aircraft
Based on eight investigations, U.S. health authorities believe that the risk is low for transmission of tuberculosis aboard transport-category aircraft. Nevertheless, the World Health Organization will publish new guidelines by late 1998 for assessing the need to notify passengers and crewmembers who may have been exposed to a person with active TB.
FLIGHT SAFETY FOUNDATION � CABIN CREW SAFETY � JULY�OCTOBER 1998
Tuberculosis (TB) is an airborne disease, and discussion of the risk of TB transmission � or spread of infection � aboard aircraft leads to questions about cabin-air quality.
During the last 10 years, U.S. research on cabin-air quality has been prompted by concerns other than TB, such as complaints of discomfort and unexplained health symptoms from some passengers and crewmembers.
Several investigations in the 1990s by the airline industry, the U.S. government, academic researchers and independent interest groups have focused on airborne microbiological concentrations and other air-quality measures aboard transport-category aircraft. Basic measurements, such as carbon dioxide levels, typically surpassed U.S. regulatory requirements. More investigations are under way, however, and a new industry standard for cabin-air quality is under development.1
The medical director of one U.S. airline said that typical aircraft environmental-control systems (ECSs) are designed, maintained and operated to provide a healthy supply of air to crewmembers and passengers.
Cris Bisgard, M.D., of Delta Air Lines, said, �If you compare air quality in an aircraft cabin to a standard office building, the airplane has far more air exchanges per hour than an office, and the air that comes into the aircraft cabin is sterile. Cabin air that is recirculated through a [high-efficiency particulate air (HEPA)] filter compares to recirculated air used in operating rooms and infectious-disease containment facilities.�2
Some epidemiological investigations of aircraft-related TB transmission said that typical patterns of cabin airflow apparently help to dilute and filter out airborne bacteria.7
Air from the air-mix chamber commonly enters near the cabin ceiling, circulates around the cabin and exits near the cabin floor. Much less air moves along the length of the inside of the cabin. Research generally shows that cabin airflow patterns do not entirely eliminate the risk that airborne bacteria will travel from one section to another, but cabin-air circulation, in combination with air filtration, significantly reduces the likelihood.
� It is evident from our investigation that aircraft ventilation systems [were] not balanced by sections of the cabin.�9
Researchers said that the preliminary bacteria-related conclusions of the investigation, which should not be considered comprehensive, were that more work is needed to characterize exposure to infectious agents in aircraft cabins; airborne bacterial concentrations were slightly higher in airport terminals than during any of 22 flight segments, except three samples taken during deboarding; that overall bacterial counts on airplanes with recirculating air-handling systems tended to be higher than those with 100 percent outside air; and that bacteria recovered were those typically shed from human skin and mucous membranes, and levels were within the range commonly seen in public environments such as schools and office buildings.
Latest Cabin-air Filters Eliminate TB Bacteria
Cabin air-filtration systems � whether certified to HEPA standards or previous standards � have been designed to enhance passenger and crew health and comfort by controlling these contaminants, he said. �The efficiency of our HEPA aircraft filters compares very well with HEPA filters we manufacture for use by hospital patients,� Lundquist said. �There is no way to prevent transmission of some diseases aboard aircraft, but we can reduce the probability of someone becoming ill if they are sitting far away from an infectious passenger. A HEPA recirculation filter will help to prevent other passengers from getting ill.�
Lundquist said that HEPA filters on transport-category aircraft remove particles with an efficiency higher than 99.97 percent at 0.3 micron (one micron is one-thousandth of a millimeter), significantly reducing the level of airborne-particulate contamination. HEPA filters provide the microbial equivalent of outside air to the passenger cabin, he said. The average bacterium has a diameter of about one micron, and strains of M. tuberculosis, which cause TB infection, range from 0.2 to one micron in diameter, Lundquist said. (By comparison, the diameter of an average human hair is about 75 microns.)
�Some people today want 20 cubic feet [0.6 cubic meter] per minute of outside air per passenger, but there is a two percent to four percent increased cost of fuel per year if you don't recirculate cabin air,� Lundquist said. �The advantage of a recirculation system aboard an aircraft is that you can filter the air so that what comes out the filter actually is cleaner than bleed air. Secondary benefits of recirculating through a filter are that normally low relative humidity increases a small amount for greater comfort and reduces ozone levels.�
Because of the physical properties of airborne particles, Lundquist said, HEPA filters also remove particles smaller than the openings between fibers of filter material. Viruses are 10 times to 100 times smaller than bacteria, for example, but research shows that they are trapped by HEPA filters.
�In HEPA design, there is a �most-penetrating particle size' at which the filter is least efficient,� Lundquist said. �Some viruses get very close to molecular level in size. But when viruses are bombarded by air molecules, they move laterally, not in a straight line. The more lateral motion, the higher the rate of filter efficiency because if a particle touches any fiber in the filter as it passes through, it will be captured. That means we can filter out particles even smaller than 0.3 microns. That is why the HEPA filter is 99.9995 percent efficient for viruses, even though they are smaller than bacteria.�
Scientists first realized that cabin-air filtration could be effective because of U.S. Department of Transportation (DOT) research about the effects of tobacco smoke aboard U.S. aircraft, he said. �We looked at the dispersion of nicotine [from cigarette smoke in aircraft cabins],� said Lundquist. �This data told us how readily something airborne will disperse up and down the aisle, what we call diffusional transport. We found that the circulation of air [from] ceiling to floor is so much greater than along the length of the cabin � it is the dominant airflow pattern. That was great news. There was not a lot of axial mixing � nicotine levels varied by a ratio of 400 to one in different parts of the cabin. This told us that improved filtration of cabin air would be a benefit. We then did some mathematical studies and used the DOT nicotine-dispersion data, working with Boeing on committees of the American Society of Heating, Refrigerating and Air-Conditioning Engineers [ASHRAE]. We proved analytically that a better filter would reduce the dispersion of contaminants throughout an aircraft.� |
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National Geographic Image Collection/Annie Griffiths Belt |
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