According to ASHRAE standards, what is the maximum allowable CO concentration in a living area?

The maximum allowable carbon monoxide (CO) concentration in a living area, according to ASHRAE standards, is 9 parts per million (ppm). This standard is established to ensure safety and comfort for occupants in residential and commercial buildings. CO is a colorless, odorless gas that can be harmful or even lethal at higher concentrations.

The threshold of 9 ppm is set to minimize health risks, as exposure to levels above this could lead to adverse health effects, particularly for sensitive populations such as children, the elderly, and those with pre-existing health conditions. Maintaining CO levels at or below this concentration helps prevent symptoms like headaches, dizziness, confusion, and in severe cases, can be life-threatening.

The values for other options are below the safety threshold but do not align with the specific standard established by ASHRAE, making 9 ppm the correct choice for ensuring a safe living environment. This limit reflects a balance between safety and practical levels that can be consistently maintained in typical living spaces.