What concentration of hydrogen sulphide can cause symptoms such as dizziness and irritation of mucous membranes?

The concentration of hydrogen sulfide (H₂S) at levels between 250 and 600 parts per million (ppm) is significant because it can lead to acute health effects. Within this range, individuals may start experiencing symptoms such as dizziness, headache, and irritation of the eyes, nose, and throat due to the gas's toxic properties.

At concentrations below 250 ppm, symptoms may be minimal, and exposure is typically not as immediately harmful. However, in the range of 250 to 600 ppm, the risk of acute exposure increases, and the irritative effects on mucous membranes become more pronounced. This level is particularly concerning in occupational settings where H₂S can be present, and safety measures should be taken to prevent exposure.

Higher concentrations, such as 600-1000 ppm, can lead to more severe symptoms and potentially life-threatening conditions, including respiratory distress and loss of consciousness, but the specific symptoms of dizziness and mucous membrane irritation are most commonly associated with the 250-600 ppm range. Going above 1000 ppm can lead to rapid unconsciousness and poses an immediate danger of fatalities.