## 4 Discussion
varied from 1 ppb to 30 ppb in urban regions and from 1 ppb to 5 ppb in the non-urban areas [54]. The concentration of total volatile organic compounds in the shop was between 339 and 32 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\), which is lower than the concentrations found in a shopping mall in Guangzhou, South China [28]. All indoor microenvironments (departments) have higher TVOC concentrations than outdoors. Among different departments, the TVOC concentrations in all departments had the highest concentration in winter. This could be explained by using a heating system and the high contributions from outside air (as the inside/outside ratio is, on average, 1.6 in winter while in summer it is 2.5). The many departments in the shop manufacture diverse goods or components that possess differing levels of TVOC content, resulting in discrepancies in emissions. In our case, the concentrations were not significantly different between departments, but in the plastics and detergents sections, there are more sources of TVOCs than in the sweets section. The type of materials, chemicals, equipment, and processes used in different departments were the same, which could explain such a slight variation. If the main sources for TVOCs in the sweets department could possibly be the ingredients and the materials used for packaging sweets [55], such as plastic wraps or containers, in the plastics and detergents departments, the main sources were the products themselves. Among TVOCs, BTEX could have an important contribution to indoor air quality. In our case, benzene and toluene concentrations were very low, while the concentrations of ortho- and para-xylene were in the same range as in other studies [28; 56]. Indoor-to-outdoor ratios for BTEX were observed to exceed 2, indicating that the influence of indoor pollution sources was more prominent than that of outdoor sources. Toluene, xylenes, ethylbenzene, and benzene have been identified as constituents of automotive exhaust emissions [57]. The regular use of cleaning solvents inside the building for the purpose of floor cleaning, as well as the presence of disinfectants, might potentially serve as significant contributing factors, given that BTEX compounds are commonly found in cleaning agents. The monoterpene concentration in the shop ranged from 76 to 121 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\) while outside, the values were significantly lower (11-34 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\)). Our values were lower than the ones found in joinery shops in Sweden (10-214 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\)), which demonstrated quite an important impact on the workers [58]. While the sources of monoterrenes outside are mainly biotic, inside the shop, the main sources were perfumes, deodorizers, and cleaning products. Indoor air quality (IAQ) ensures a healthy and efficient atmosphere in shops and other industrial facilities. The regulation for the different chemicals' maximum levels differs between countries (see the review regarding European legislation in [59]). For example, the WHO maximum guidance for formaldehyde is 100 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\) while the regulation varies between 120 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\) in Germany and 50 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\) in Finland. In our cases, the formaldehyde concentration did not exceed 100 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\), while the TVOCs were under 500 \(\mathrm{\SIUnitSymbolMicro g/m^{3}}\). Implementing an indoor air quality (IAQ) method to manage volatile organic compounds (VOCs) in businesses is a thorough and effective technique that fosters a healthy and ecologically conscious workplace. Shops may safeguard employee health, adhere to laws, and support sustainability by identifying sources, applying control measures, and maintaining acceptable indoor air quality (IAQ). Lactic acid is the predominant chemical constituent found in human sweat. It is emitted from our skin, undergoes atmospheric dispersion, and adheres to various surfaces, including walls.