Recommended concentration limits of typical indoor air contaminants

From the view of both objective and subjective factors, the indoor air quality (IAQ) evaluation was considered. Carbon dioxide (CO₂) and formaldehyde (HCHO) were selected as the typical contaminants of indoor air, and the evaluation method of logarithmic index was adopted as the evaluation means of IAQ. Then the recommended limits (RL) of typical contaminants CO₂ and HCHO were given through analysis and calculation. The limits of CO₂ and HCHO in Indoor Air Quality Standard of China or other existing standards probably correspond to the level of PD=25%. The result shows that the existing standards fail to meet the requirement of the definition of "acceptable indoor air quality", that is to say, less than 20% of the people express dissatisfaction. When PD=20%, RL of CO₂ and HCHO are 728×10^-6 and 0.068×10^-6 respectively, which are stricter than the limits in the existing standards. The method proposed in this paper is applicable to 13.1%≤PD≤86.7%.