H_2_S at a concentration of 50ppm (roughly what you’d get if you inhaled a fart directly into your lungs) you’d suffer Slight conjunctivitis (“gas eye”) and respiratory tract irritation after 1 hour. May cause digestive upset and loss of appetite.3.
Any practical dosage would be around 3ppm. At that rate it would be Odor becomes more offensive at 3-5 ppm. Above 30 ppm, odor described as sweet or sickeningly sweet.. The key point here is that around 10 times the usual dosage, a fart won’t stink. Instead it will smell “sweet.”
At 100ppm – which is around 30 times the usual dose – you won’t smell anything at all because you’ll lose your sense of smell (olfactory fatigue or paralysis).
At 1000ppm – 300 times the usual dose – it’s nearly instant death.