Indoor air pollution is a serious public health issue caused by the accumulation of numerous toxic contaminants within enclosed spaces. Particulate matter (PM_2.5 and PM₁₀), biological contaminants (mould, bacteria, and allergies), inorganic gases (carbon monoxide, carbon dioxide, ozone, and nitrogen dioxide), and a variety of volatile organic compounds (VOCs) are examples of common indoor air pollutants. VOCs are one of the chief indoor contaminants, and their effects on human health have made indoor air quality a serious concern. Indoor VOC concentrations are frequently higher than outdoor levels, according to studies, which raises the danger of exposure, particularly for young people and those with respiratory disorders. VOCs originate from both biogenic and anthropogenic sources, and they can create secondary pollutants like ozone and aerosols, which can lead to cardiovascular and pulmonary problems. Prolonged exposure to VOCs has been associated with respiratory irritation, neurological effects, and an increased risk of chronic diseases. This review examines the primary sources, sampling and analysis approach, and health impact of VOCs in indoor air. Additionally, we compared worldwide regulatory guidelines for VOC exposure limits, emphasizing the need for strict exposure limits to protect human health.

Indoor air quality is a significant aspect of public health, yet it remains less studied than outdoor air pollution. Understudied indoor pollutants include volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). This review focuses on these two groups of compounds known for their health effects, including respiratory issues, neurological disorders, and carcinogenicity. We systematically compiled and analyzed data from studies reporting measured concentrations of VOCs and PAHs in European indoor environments—homes, schools, and offices—published in the past two decades. Concentration levels vary substantially across studies, influenced by regional differences, climate, building type, ventilation systems, and indoor activities. Identified sources include tobacco smoke, cooking, heating (e.g., biomass burning), and off‐gassing from construction and furnishing materials. Our analysis reveals clear geographic patterns: lower concentrations of VOCs and PAHs are consistently reported in Northern and Western European countries, likely due to stricter air quality regulations, cleaner outdoor air, greater use of electric heating, and more advanced ventilation systems. Conversely, higher concentrations are more commonly observed in Southern and Eastern Europe, where biomass heating and poorer ventilation remain more prevalent. Seasonal variation also has a significant role, with higher indoor levels typically measured during colder months due to increased heating and reduced air exchange. This highlights the need for improved indoor air quality management practices and regulatory standards to minimize the health risks associated with VOCs and PAHs. This review of 46 scientific publications is aimed at informing future studies and guiding future field measurements and risk assessments in epidemiological studies.

Polycyclic aromatic hydrocarbons (PAH) are key components of particulate matter (PM) in terms of the toxicological risk of polluted air. Although commonly monitored in ambient air, PAHs are also present in indoor air, making the measurement of indoor PAH content essential for understanding the health risks associated with indoor environments. This study presents findings from measurements conducted across 37 households where children resided, using 7-day sampling campaigns to collect PM₁. The health risk assessment methods are detailed herein, along with a source apportionment analysis to explore the associations with potential sources and differences from ambient air concentrations. Additionally, the incremental lifetime cancer risk (ILCR) was calculated to assess long-term health risks associated with exposure to indoor PAHs. The results showed consistently higher PAH concentrations in outdoor environments (from 0.079 ng m⁻³ for dibenzo(a,h)anthracene to 1.638 ng m⁻³ for benzo(b)fluoranthene) compared to indoor environments (from 0.029 ng m⁻³ for dibenzo(a,h)anthracene to 0.772 ng m⁻³ for indeno(1,2,3-cd)pyrene), suggesting significant transfer of PAHs from outdoor to indoor air. The source apportionment analysis indicated that traffic emissions, fossil fuel combustion, and residential heating were the predominant sources of PAHs in both environments, with the concentration of indoor PAHs largely influenced by gasoline and liquid fossil fuel combustion. The diagnostic ratios supported these findings, with coal and biomass as additional sources impacting outdoor PAH levels. The ILCR analysis revealed that the exposure levels for both children (indoors at 1.78 × 10⁻⁵, outdoors at 1.92 × 10⁻⁶) and adults (indoors at 1.15 × 10⁻⁵, outdoors at 1.24 × 10⁻⁶) remained below the U.S. EPA’s risk threshold, suggesting limited carcinogenic risk under typical household conditions in this study. These findings emphasize the complexity of PAH distribution between indoor and outdoor environments, illustrating how urban outdoor pollution sources contribute to indoor air quality and highlighting the relevance of effective air quality management strategies.

Polycyclic aromatic hydrocarbons (PAHs), due to their harmful carcinogenic and mutagenic effects on human health, are significant organic pollutants in the air. Accelerated Solvent Extraction (ASE) at high temperature and pressure is a technique increasingly used to prepare samples for determining organic pollutants in environmental samples. To investigate ASE's efficacy in extracting organic pollutants bound to airborne particulate matter, model samples were prepared by spiking with known concentrations of a certified standard of PAHs. The following variables were optimised: solvent type, number of extraction cycles, extraction temperature, and flushing volume. ASE efficiency was compared with ultrasonic liquid extraction (ULE) using PAH certified reference material and real samples. All samples were analysed by high performance liquid chromatography with fluorescence detection and variable excitation and emission wavelength. Satisfactory efficiency for all PAHs were achieved using a solvent mixture of toluene and cyclohexane (7 : 3, v/v), two extraction cycles at 125 °C, and a flushing volume of 70 % of the cell volume, with recoveries exceeding 97 % for all PAHs except fluoranthene and pyrene (87 %).

This study aimed to investigate the concentrations of BTEX (benzene, toluene, ethylbenzene, ortho-xylene (o-), and meta and para-xylene (m-,p-)) in Croatian households between December 2023 and January 2025. The results showed that BTEX concentrations were higher indoors than outdoors, suggesting a considerable contribution from indoor sources. Significant statistical differences were found between indoor and outdoor levels of ethylbenzene, m-,p-xylene, and o-xylene, especially during cold periods when indoor activities increase and ventilation decreases. Spearman’s correlation analysis showed weak correlations between benzene and other BTEX compounds, implying multiple distinct sources such as cooking, smoking, and outdoor air infiltration.