bripl said:10 ppm are you sure about that
Yes, In a room cigarette smoke will quite easily give a reading of 4ppm.
35ppm in the room is the maximum allowable concentration for continuos exposure in any 8 hour period, as recommended by the OSHA occupational safety and health administration.
On the other hand
Flue gas readings would be in the region of 55ppm - 90ppm