Volatile Organic Compounds Emissions in Indoor Environments

Volatile organic compounds (VOCs) encompass a diverse class of carbon-based chemicals that readily evaporate at ambient temperatures and accumulate in enclosed spaces. Indoor environments act as both sources and sinks for VOCs, with emissions arising from building materials, furnishings, cleaning agents, personal care products and occupant activities such as cooking and smoking. Outdoor air infiltration, temperature, relative and absolute humidity, and ventilation rates further modulate indoor VOC concentrations. Elevated levels have been linked to irritation of the eyes, nose and throat, exacerbation of asthma and other respiratory conditions, and in some cases long-term carcinogenic risks. Understanding the interplay between source strength, environmental conditions and removal processes is critical for designing effective mitigation strategies, informing building codes and developing real-time monitoring systems. This synthesis highlights recent advances in emission modelling, exposure assessment and health-oriented research, underscoring the global significance of indoor VOC management for public health and sustainable building design.

Research from Nature Portfolio

Investigations into the role of humidity on material emissions have revealed that absolute humidity exerts a dominant influence on the initial emittable concentration of formaldehyde and hexaldehyde from composite wood panels. Experiments show that as absolute humidity rises, the maximum concentration available for off-gassing can increase by an order of magnitude, with a linear relationship identified between the logarithm of emittable concentration and humidity. Derived correlations permit prediction of emission rates under varying moisture conditions, offering a practical tool for source control and for refining indoor air quality models in real-world scenarios.

Volatile Organic Compounds Emissions in Indoor Environments publication trend

The graph below shows the total number of articles in volatile organic compounds emissions in indoor environments across all publications each year (not limited to Nature Index journals).

Technical terms

Volatile Organic Compounds (VOCs): Organic chemicals with high vapour pressure at room temperature that readily partition into the gas phase.

Initial Emittable Concentration (Cm,0): The maximum concentration of a VOC that can be released from a material under specified environmental conditions before depletion effects dominate.

Air-Exchange Rate: The volume of outdoor air introduced into an indoor space per unit time, typically expressed in air changes per hour (ACH) or L s⁻¹ m⁻² of floor area.

Absolute Humidity: The mass of water vapour present in a unit volume of air, influencing the sorption and diffusion of VOCs in porous materials.

Ventilation Threshold: A critical airflow rate above which further increases do not significantly enhance the removal or dilution of VOC emissions from indoor surfaces.

References

1. Theoretical Threshold for Estimating the Impact of Ventilation on Materials’ Emissions. Environmental Science and Technology (2024).
2. Volatile Organic Compounds (VOCs) from Wood and Wood-Based Panels: Methods for Evaluation, Potential Health Risks, and Mitigation. Polymers (2020).
3. Pulmonary Health Effects of Indoor Volatile Organic Compounds—A Meta-Analysis. International Journal of Environmental Research and Public Health (2021).
4. Influence of humidity on the initial emittable concentration of formaldehyde and hexaldehyde in building materials: experimental observation and correlation. Scientific Reports (2016).