SECRET
UK RESTRICTED
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ANNEX B
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ODOURS
1. Some cases have occurred where peculiar odours have been reported. These seem to be produced by microwaves or high energy electrical fields.
2. These effects are well understood and can be replicated in the laboratory. Normally the smell is described as ‘sulphurous’, ‘electrical burning’ or ozone-like.
3. During electrical discharges in the atmosphere many electrical compounds are formed. Nitric oxide, for example, reacts with other atmospheric gases to form nitro-benzene, which smells like bitter almonds.
4. The slow decay of activated nitrogen can exhibit a white glow and may be the reason for white trails (or ‘tails’) sometimes described by witnesses, whether or not the witness has smelled the chemical reaction.
5. Reports have been received where a ‘strange odour’ hangs in the air for some time after an event.
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B-1
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UNCLASSIFIED
UK RESTRICTED
SECRET