We aimed to assess, for the first time, the nature of the indoor air contamination of hospitals. More than 40 volatile organic compounds (VOCs) including aliphatic, aromatic and halogenated hydrocarbons, aldehydes, alcohols, ketones, ethers and terpenes were measured in a teaching hospital in France, from sampling in six sampling sites – reception hall, patient room, nursing care, post-anesthesia care unit, parasitology-mycology laboratory and flexible endoscope disinfection unit – in the morning and in the afternoon, during three consecutive days. Our results showed that the main compounds found in indoor air were alcohols (arithmetic means ± SD: 928±958 µg/m³ and 47.9±52.2 µg/m³ for ethanol and isopropanol, respectively), ethers (75.6±157 µg/m³ for ether) and ketones (22.6±20.6 µg/m³ for acetone). Concentrations levels of aromatic and halogenated hydrocarbons, ketones, aldehydes and limonene were widely variable between sampling sites, due to building age and type of products used according to health activities conducted in each site. A high temporal variability was observed in concentrations of alcohols, probably due to the intensive use of alcohol-based hand rubs in all sites. Qualitative analysis of air samples led to the identification of other compounds, including siloxanes (hexamethyldisiloxane, octamethyltrisiloxane, decamethylcyclopentasiloxane), anesthetic gases (sevoflurane, desflurane), aliphatic hydrocarbons (butane), esters (ethylacetate), terpenes (camphor, α-bisabolol), aldehydes (benzaldehyde) and organic acids (benzoic acid) depending on sites. For all compounds, concentrations measured were lower than concentrations known to be harmful in humans. However, results showed that indoor air of sampling locations contains a complex mixture of VOCs. Further multicenter studies are required to compare these results. A full understanding of the exposure of healthcare workers and patients to complex mixtures of chemical compounds can then be related to potential health outcomes.

Sampling and sample preparation plays an important role in untargeted analysis as it influences final composition of the analyzed extract and consequently reflection of the metabolome. In the current work, mechanism of bactericidal action of cinnamaldehyde (CA) against Escherichia coli (E. coli) during bacteria growth applying high-throughput solid-phase microextraction in direct immersion mode coupled to a high-performance liquid chromatography–mass spectrometry system was investigated. Numerous discriminant metabolites due to CA addition to the bacteria culture were mapped in the E. coli metabolic pathways. We propose new metabolic pathways confirming that CA acts as an oxidative stress agent against E. coli. The results of the current research have successfully demonstrated that CA changes the bacterial metabolism through interactions with different biochemical families such as proteins, nucleic acids, lipids, and carbohydrates, which needs further validation by proteomics and transcriptomics studies. The results presented here show the great potential of the novel approach in drug discovery and food safety.

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