I know what you mean - I can't tell either. But if in doubt I go anyway because the one time I didn't he ended up being admited to starship with a low blood/oxygen level. I can't even tell with myself lol - my mum's had to intervene and force me to go to the after hours.
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DS1 Feb 02; DS2 Oct 04; DS3 June 07
Food & environmental allergies, eczema,
anaphylaxis, hayfever, food chemical intolerance and asthma.
Treat the earth well: it was not given to you by your parents,
it was loaned to you by your children. ~ Ancient Indian Proverb