###### Abstract  
Indoor air quality has become a topic of great concern. Burning incense has recently been identified as one of the primary sources of volatile organic compounds, specifically benzene, in an indoor setting. The current paper aims to evaluate volatile organic compound (VOC) emissions, particularly benzene, within indoor environments through the utilization of an experimental clean room. Experimental findings showed that 10 types of incense sticks emitted benzene in concentrations between 11.1 and 66.5 \(\upmu\)m\({}^{-3}\), which were 2.5 lower than the limit suggested for non-occupation indoor exposure (160 \(\upmu\)m\({}^{-3}\)), identified by the American Association of Industrial Hygienists (ACGH). Furthermore, a correlation between the dimensions (diameter and length) of the combustible parts in an incense stick was investigated and indicated a slight influence on the release of benzene. Taking into consideration the substantial influence benzene has on human health, coupled with a lack of precise legislation regarding indoor air quality in residential settings, this research serves as an initial investigation into the noteworthy effects of burning incense in private and public indoor settings. benzene; aromatic substances; indoor air quality; human health; incense; VOC; human exposure +
Footnote †: journal: Applied sciences  
merous VOCs (e.g., benzene, limonene, and \(\alpha\)-pinene) are, in fact, produced by fraganced consumer products [5]-for instance, incense. A work by BEUC (i.e., Bureau europeen des unions de consommateurs) determined a concentration of benzene emitted in the test room of 221 \(\upmu\)g m\({}^{-3}\)[6]. Likewise, [PERSON] et al. (2007) reported an average emission of benzene in temples in Hong Kong of 115 \(\upmu\)g m\({}^{-3}\), which exceeds the standard value (16.1 \(\upmu\)g m\({}^{-3}\)) by almost 8 times [7]. A chamber experiment exhibited an emission of benzene of 18-117 \(\upmu\)g m\({}^{-3}\), due to the combustion of incense sticks [8]. Likewise, a concentration of benzene of more than 200 \(\upmu\)g m\({}^{-3}\) was released by incense during a chamber experiment [6; 9]. However, a clear assessment of the effects on humans is challenging due to limited studies on exposure [8]. Finally, it should be underlined that the European standardization committee produced three different standards, including EN 1673 [10], EN 16739 [11], and EN 16740 [12]. Benzene, toluene, ethylbenzene, and xylene are VOCs of particular concern (Table 1). They are known as the BTEX groups (i.e., benzene, toluene, ethylbenzene, and xylene) and are significantly present in indoor air. Among them, benzene demands particular attention. Evidence from human exposure and animal studies has confirmed the carcinogenicity of benzene [13]. Epidemiological studies have, in fact, proven the correlation between exposure to benzene and the development of aplastic anemia and leukemia [14], especially in children [15]. Likewise, people exposed to toluene and xylenes showed several adverse effects; toluene exposure determines a decrease in luteinizing hormone (LH) and follicle-stimulating hormone (FSH), significantly increasing the risk of spontaneous abortion [16]. Evidence has also proven that indoor air is the main route of human exposure to VOCs. VOCs are, in fact, typically present in higher concentrations in indoor air than in outdoor air [17]. However, few studies have been conducted on the contribution of burning incense to human exposure to VOCs. A search on Scopus database using the keywords \"Incense AND VOCs AND indoor AND air\" provided only 23 articles, underlining the need to carry out more in-depth analyses on this issue. Current scientific literature reported that emissions of VOCs in indoor environments are due to activities, such as smoking, cooking, the use of liquefied petroleum gas combustion, natural gas equipment and biomass heating [9; 18], and burning incense [9].