Indoor Air Quality Assessment Based on Human Physiology – Part 2 . Limits

The increasing requirements for indoor air quality in buildings need more exact criteria in order to ascertain the real condition of the environment and to allow better optimization of its level, to remove “sick building” symptoms, i.e. to get the real comfort within a building. Human physiology research makes evident that the Weber-Fechner law applies not only to noise perception, but also to the perception of other environmental components. Based on this fact, new decibel units for odor component representing indoor air quality in majority locations have been proposed: decicarbdiox dCd (for carbon dioxide CO2) and decitvoc dTv (for total volatile organic compound TVOC) – see Part 1 of this paper. Equations of these new units have been proved by application of a) experimental relationships between odor intensity (representing odor perception by the human body) and odor concentrations of CO2 and TVOC, b) individually measured CO2 and TVOC levels (concentrations) – from these new decibel units can be calculated and their values compared with decibel units of noise easured in the same locations. To be able to evaluate the indoor air quality in practice, we need to establish limits or, more exactly, admissible and tolerable ranges for both unadapted and adapted persons (P).


Introduction
The increasing requirements for indoor air quality in buildings need more exact criteria in order to ascertain the real condition of the environment and to allow better optimization of its level, to remove "sick building" symptoms, i.e. to get the real comfort within a building.
Human physiology research makes evident that the Weber-Fechner law applies not only to noise perception, but also to the perception of other environmental components.Based on this fact, new decibel units for odor component representing indoor air quality in majority locations have been proposed: decicarbdiox dCd (for carbon dioxide CO 2 ) and decitvoc dTv (for total volatile organic compound TVOC) -see Part 1 of this paper.
Equations of these new units have been proved by application of a) experimental relationships between odor intensity (representing odor perception by the human body) and odor concentrations of CO 2 and TVOC, b) individually measured CO 2 and TVOC levels (concentrations) -from these new decibel units can be calculated and their values compared with decibel units of noise easured in the same locations.
To be able to evaluate the indoor air quality in practice, we need to establish limits or, more exactly, admissible and tolerable ranges for both unadapted and adapted persons (P).

Carbon dioxide
The starting points of these values are based on various studies (e.g.[23]) whose results are listed in Table 2.1 and in Fig. 2.1.See also Tables 1.2 and 1 .3 (p. 24,25) and Fig. 1.4 (p. 26) in Part 1.
The optimal value overwhelmingly corresponds PD = 20 %.A better value of PD = 10 % could be prescribed   A worse value of PD = 30 % could be accepted as an admissible value.These values differ for unadapted and adapted persons (as introduced by BSR/ASHRAE 62-1989 R).
The long-term tolerable values, which are quoted in occupational health standards and studies, are reached in buildings with sick building syndrome (SBS).Short-term tolerable values are those at the beginning of the toxic range both for unadapted and adapted persons.Also the lowest, detectable value is the same for unadapted and adapted person (P).
For adapted persons the same Eq.( 1) is valid, but the prescriptive outdoor air requirements for them, according to [9], is only 2.5 1×s -1 ×p -1 CO 2 load caused by a sedentary person and outdoor CO 2 concentration remain the same, i.e.G rCO 2 19 = 1×h -1 ×p -1 , r eCO 2 310 = ppm.So CO 2 indoor concentration r iCO 2 can be calculated: ( ) where r iCO 2 2420 = ppm, i.e. for 20 % dissatisfied adapted persons, CO 2 indoor air concentration can be raised from 1015 ppm to 2420 ppm.Presuming the same character of the curve, i.e.
The long-term tolerable value (5000 ppm, 91 dCd; the end of the SBS range) is based on USSR space research; the short-term tolerable value (15000 ppm, 134 dCd; the beginning of the toxic range) is taken from British Guidance Note EH 40/90 as described previously.

Fig
Fig. 2.2: The percentage of dissatisfied sedentary subjects as a function of the carbon dioxide concentration above outdoors

Table 2
.1: Various limits and ranges for CO 2 concentrations: un = unadapted persons, asthm.=asthmatic persons, ?= for values of asthmatic persons there is no experimental background (analogy to TVOC is presumed)for asthmatics and for persons with increased requirements, i.e. those allergic to the environment and operators in airport control towers and power stations (especially atomic power stations).This is analogous to the TVOC limits (see later).

Table 2 .
1: Various limits and ranges for CO 2 concentrations: un = unadapted persons, asthm.= asthmatic persons, ?= for values of asthmatic persons there is no experimental background (analogy to TVOC is presumed) (continue)