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File: 123096_sep96_decls1_0076.txt
Subject: DETECTION OF MEDICAL DEFENSE AGAINST BIOLOGICAL MATERIALS
Unit: OTSG
Parent Organization: HSC
Box ID: BX003203
Folder Title: DETECTION OF MEDICAL DEFENSE AGAINST BIOLOGICAL MATERIALS
Document Number: 1
Folder Seq #: 21
than the higher layers. 'I he L ompc ra L t4 re Invers ion g enera II y
has its maximum value during the iale night hours. Cround
configuration also Lakes its part in aeros@l dissemination.
'rhe topography guides air current circulation, so creating
unfavourable zones for particle fallout. Conversely, as is
the Case with valleys, the wind could carry the aerosol and
deposit it in a preferential location.
( c ) Rain and snow-could also modify particle concentration in
the air, but unly when arcunts of precipitation are large.
(d ) I'huS the area covered by a biological aerosol and the
distance which it travels before its concentration has fallen
below a minimum effective value, is dependent on the velocity
of the wind, the Stability of the atmosphere and the ground
above which it is generated. C)ne could understand
difficulties to predict, in terms of t4me and space, what
wotili be thp de@tiny of an in
nature or not. The conditions for the greatest spread of the
cloud are a stable atmosphere in combination wich a low
velocity wind of variable direction.
(2) meteorology and biological decay:
(a ) solar radiation. The ultraviolet part. of the I ight
spectrum has a germicidal action against all microorganisms.
The effect Of solar radiation decreases when air humidity is
high (greater than 70%). A high degree of air pollution by
dust particles also protects microorganisms from germicidal
radiation. IL has been found that bacterial aerosols
generated from dry material are less sensitive to the lethal
effect of radiation than aerosols generated in sprayed liquid
suspensions. 'he lethal effect of sunlignz, which is less
marked but Still significant in diffuse daylight, makes it
likely that a biological operation would 're carried out at
night for greatest effectiveness.
(b) Relative humidity. Among the atmospi-,eric conditions
affecting the rate of inactivation of airborne microorganisms,
relative humidity is also very important. The rate of decay
of bacterial viability usually is higher at low, rather than
at high humidity values, although for several organisms a
maximum inaccivarion occurs at relatively moderate humidity
). The addition of certain organic compounds
to the spray suspension may substantially reduce the
dehydration rate of the biological agents thus protecting them
@from rapid inactivation. Further development of
"microencapsulation" might increase consicrerably the potential
threat of biological operations, because it can protect
microorganisms from Ultraviolet radiation.
(c) Chemical Composition of the Atmosphere. Solar radiation
also produces complex photochemical reactions between various
13
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Document 109 f:/Week-36/BX003203/DETECTION OF MEDICAL DEFENSE AGAINST BIOLOGICAL MATERIALS/detection of medical defense against biological :1217960927452
Control Fields 17
File Room = sep96_declassified
File Cabinet = Week-36
Box ID = BX003203
Unit = OTSG
Parent Organization = HSC
Folder Title = DETECTION OF MEDICAL DEFENSE AGAINST BIOLOGICAL MATERIALS
Folder Seq # = 21
Subject = DETECTION OF MEDICAL DEFENSE AGAINST BIOLOGICAL
Document Seq # = 1
Document Date =
Scan Date =
Queued for Declassification = 01-JAN-1980
Short Term Referral = 01-JAN-1980
Long Term Referral = 01-JAN-1980
Permanent Referral = 01-JAN-1980
Non-Health Related Document = 01-JAN-1980
Declassified = 17-DEC-1996