**Acknowledgements**

*Indoor Environment and Health*

spread indoor [20].

implementation.

toxic gas, and the oxygen deprivation appears [19].

ane; tridecane; tetradecane; and pentadecane.

technical performance or act as flame retardants [7, 10].

long after the activity generating the chemicals had finished [20].

2000 ppm, the sensation of poor air combines with sleepiness, between 2000 and 5000 ppm; the symptoms are drowsiness, headaches, loss of attention, and even nausea or increased heart rate. Over 5000 ppm, CO2 could be considered a potential

Particularly, space maximum allowable concentration of CO2 is 10,000 ppm [2]. The *VOCs* are a numerous class of organic compounds, with small- or mediumsized molecules, present indoor especially from the construction and decorating materials, as paints, varnishes, and wax; hygiene; and beauty products for cleaning/ disinfecting, degreasing, personal care, and hobby products. Commonly, the levels of the most usual VOCs are several times higher inside homes than outside, even for homes located in rural or in highly industrial areas. A characteristic of the VOCs indoor is the fact that the exposure to elevated concentrations can persist in the air

Among the most common VOCs, formaldehyde, aromatic and aliphatic hydrocarbons, carbonyl compounds, as well as chlorinated organic compounds are widely

*Formaldehyde* is one of the most common VOCs. It is a colorless gas with a sharp smell. The sources of formaldehyde indoor are lots of building and finishing materials: plywood, particleboard, glues, waterproof fabrics, foams, and fuel burning [21]. It should be noted that formaldehyde is one of the most toxic indoor air pollutants [13] and its high presence probability indoors due to the above-mentioned sources suggests the need of action in the direction of source-reduction measure

The main *aromatic*, *naphthenic*, *and aliphatic hydrocarbons* cited to be present in the indoor air, especially in the car interiors, are: benzene; toluene; ethylbenzene; xylenes; styrene; propyl-benzene; cumene; ethyl-methyl-benzenes; trimethylbenzenes; naphthalene; methylcyclopentane; 1,2-dimethylcyclopentane; cyclohexane; dimethylcyclopentane cis- and trans-1,2-dimethylcyclopentane; methylcyclohexane; ethylcyclopentane; 1,4-dimethylcyclohexane; trimethylcyclohexanes; propylcyclohexane; methyl-propyl-cyclohexanes; hexane; 3,3-dimethylpentane; 2-methylhexane; 2,3-dimethylpentane; 3-methylhexane; 3-ethylpentane; heptane; dimethylhexanes; 2-methylheptane; octane; 2,5-dimethylheptane; 3-methyloctane; 2,6-dimethyloctane; 2-methylnonane; decane; undecane; dodec-

Methylene chloride (dichloromethane), benzyl chloride, carbon tetrachloride,

*Radon* is a radioactive, colorless, odorless, and tasteless gas [22] which occurs naturally as an intermediate step in the normal radioactive decay chains of thorium and uranium. These last elements are often found in the composition of construction materials (i.e., bricks, ceramic tiles, cement, etc.), and therefore the buildings made from these materials could accumulate in time (if the ventilation system is not appropriate) a huge amount of this radioactive gas with dangerous action for

In order to better understand and control IAQ problems in living spaces, some

general aspects related to chemical and particle content of air, with practical

chloroform, trichloroethylene, tetrachloroethylene, p-dichlorobenzene, and 1,1,1-trichloroethane used together with polybrominated diphenyl ethers, hexabromocyclododecanes, tetrabromobisphenol A, and polybrominated biphenyls are some examples of *halogenated compounds* used in plastic materials to improve their

**94**

human health [23].

**6. Conclusions**

This work was partially supported by the following projects: EFECON, Ecoinnovative Products and Technologies for Energy Efficiency in Construction; POC/71/1/4, Knowledge Transfer Partnership, Cod MySMIS: 105524, ID: P\_40\_295, Project co-financed by the European Regional Development Fund; and RDI Program for Space Technology and Advanced Research (STAR), project no. 157/2017, financed by Romanian Space Agency (ROSA).
