Indoor Air Chemistry and Volatile Organic Compound Dynamics

Indoor environments host a complex interplay of chemical processes that govern the concentrations, transformations and fate of volatile organic compounds (VOCs). Primary sources of VOCs include human occupants (via breath and skin emissions), building materials, furnishings and consumer products. These compounds undergo oxidation reactions with oxidants such as ozone, hydroxyl radicals and nitrate radicals, yielding secondary products that may partition between gas and particle phases, modify indoor oxidative capacity and influence occupant exposure to irritants and potential toxicants. Heterogeneous reactions at surfaces—walls, textiles and human skin—mediate both the removal of reactive species and the formation of semi-volatile oxidation products. Ventilation and filtration rates control the residence time of reactants and products, while environmental factors such as temperature, humidity and light exposure modulate reaction kinetics. The dynamics of VOCs in indoor air thus reflect a balance between emissions, transport, chemical transformation and deposition, with implications for air quality management, health risk assessment and building design strategies to mitigate adverse exposures.

Research from Nature Portfolio

Recent studies have revealed that human groups emit characteristic blends of VOCs that vary reproducibly with collective activities and emotional stimuli. Continuous monitoring in a cinema setting demonstrated that volatile tracers such as isoprene and aldehydes synchronise with film scenes, offering a novel method to non-invasively assess group responses via chemosignal analysis. In parallel, investigations into multiscale indoor chemistry have highlighted the role of clothing in ozone-driven reactions. Taking account of molecular kinetics and air-flow dynamics, researchers showed that squalene deposited on garments can persist for hours and react with ozone to generate semi-volatile oxidation products. Computational fluid dynamics further indicated that primary ozonolysis products concentrate preferentially in the breathing zone, emphasising the combined importance of surface chemistry and flow patterns in shaping occupant exposure.

Indoor Air Chemistry and Volatile Organic Compound Dynamics publication trend

The graph below shows the total number of articles in indoor air chemistry and volatile organic compound dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Volatile organic compounds (VOCs): organic chemicals that readily evaporate at ambient conditions, contributing to indoor pollution and odour.

Ozonolysis: oxidative reaction of ozone with unsaturated organic compounds, leading to cleavage of double bonds and formation of oxygenated products.

Secondary organic aerosol (SOA): particulate matter formed from the oxidation of VOCs, which can influence air quality and health.

Air exchange rate: the rate at which indoor air is replaced by outdoor air, typically expressed in air changes per hour (h⁻¹).

Deposition velocity: the rate at which gas-phase species are removed by surfaces, indicating surface reactivity.

Squalene: a skin‐surface lipid that undergoes oxidation with ozone to yield semi-volatile organic compounds.

References

1. Cinema audiences reproducibly vary the chemical composition of air during films, by broadcasting scene specific emissions on breath. Scientific Reports (2016).
2. The impact of clothing on ozone and squalene ozonolysis products in indoor environments. Communications Chemistry (2019).
3. Impact of surface ozone interactions on indoor air chemistry: A modeling study. Indoor Air (2017).
4. Indoor ozone/human chemistry and ventilation strategies. Indoor Air (2019).