Table 4.
Pathophysiological responses to hydrogen sulfide at various concentrations in air.
| Concentrations (ppm) | Expected Effects/Symptoms |
|---|---|
| 0.00011–0.00033 | Typical background concentrations (OSHA) |
| 0.0005 | Lowest concentration detectable by human olfactory senses (ATSDR) |
| 0.01–1.5 | Odor threshold (when rotten egg smell is first noticeable to some). Odor becomes more offensive at 3–5 ppm. Above 30 ppm, odor described as sweet or sickeningly sweet (OSHA) |
| 2–5 | Prolonged exposure may cause nausea, tearing of the eyes, headaches or loss of sleep. Airway problems (bronchial constriction) in some asthma patients (OSHA) |
| 20 | Possible f atigue, loss of appetite, headache, irritability, poor memory, dizziness (OSHA) |
| 50 – 100 | Slight conjunctivitis (“gas eye”) and respiratory tract irritation after 1 cause digestive upset and loss of appetite (ANSI and OSHA)-hour exposure. May |
| 100 | Coughing, eye irritation, loss of sense of smell after 2–15 minutes. Altered respiration, pain in the eyes and drowsiness after 15–30 minutes followed by throat irritation after 1 hour. Several hours of exposure results in gradual increase in severity of these symptoms and death may occur within the next 48 hours (ANSI and OSHA) |
| 100 – 150 | Loss of smell (olfactory fatigue or paralysis) (OSHA) |
| 200 – 300 | Marked conjunctivitis and respiratory tract irritation after 1 hour of exposure (ANSI and OSHA). Pulmonary edema may occur from prolonged exposure (OSHA) |
| 500 – 700 | Staggering, collapse in 5 minutes (OSHA). Serious damage to the eyes. Loss of consciousness and possibly death in 30 minutes - 1 hour (ANSI and OSHA) |
| 700 – 1000 | Rapid unconsciousness, “knockd own” or immediate collapse within 1 to 2 breaths, cessation of respiration and death within minutes (ANSI, ATSDR, and OSHA) |
| 1000 – 2000 | Unconsciousness at once, with early cessation of respiration and death in a few minutes. Death may occur even if individual is removed to fresh air at once (ANSI and OSHA) |