1 Answer

At what level does carbon monoxide become toxic?
For healthy adults CO becomes toxic when it reaches a level higher than 35 ppm (parts per million) with continuous exposure over an eight hour period.. When the level of CO becomes higher than that a person will suffer from symptoms of exposure. Mild exposure over 2-3 hours (a CO level between 35 ppm and 200 ppm) will produce flu-like symptoms such as headaches, sore eyes and a runny nose. Medium exposure (a CO level between 200 ppm to 800 ppm) will produce dizziness, drowsiness and vomiting in as little as 1 hour. This level of exposure is deemed to be life threatening once three hours has passed. Extreme exposure (a CO level of 800 ppm and higher) will result in unconsciousness, brain damage and death in as little as a few minutes. OSHA guidelines state that the maximum exposure over an eight hour time period is 35 ppm.