Volatile Organic Compound Emissions in Urban Atmospheres

Volatile organic compounds (VOCs) represent a diverse class of carbon-based chemicals that readily evaporate at ambient temperatures. In urban environments their emissions arise from vehicular exhaust, fuel evaporation, industrial processes, volatile chemical products (such as solvents and personal care items) and biogenic sources including urban greenery. Once released into the atmosphere, VOCs undergo photochemical oxidation, driving the formation of tropospheric ozone and secondary organic aerosols (SOA). These processes influence air quality, visibility and human health, and interact with nitrogen oxides and other pollutants to determine regional smog episodes and fine particulate matter burdens. Accurate characterisation of VOC emission rates and chemical reactivity is fundamental for designing effective mitigation strategies, refining air‐quality models and informing regulatory policies across global megacities.

Research from Nature Portfolio

Recent studies have highlighted the health significance of VOC oxidation products, notably secondary organic aerosols. One seminal investigation quantified the association between long-term SOA exposure and cardiorespiratory mortality across the United States. By combining advanced predictive algorithms for SOA formation with epidemiological data, researchers demonstrated that SOA is more strongly linked to death rates than total fine particulate mass. Both biogenic and anthropogenic carbon sources contribute to SOA, underscoring the need to account for diverse VOC precursors in public-health and air-quality management.

Volatile Organic Compound Emissions in Urban Atmospheres publication trend

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

Technical terms

Volatile organic compound (VOC): An organic chemical with sufficient vapour pressure to exist in the gas phase under ambient conditions.

Secondary organic aerosol (SOA): Particulate matter formed in the atmosphere through oxidation of VOCs, contributing to fine aerosol mass.

Eddy covariance: A flux‐measurement technique that quantifies turbulent exchange of gases between the surface and atmosphere.

Proton‐transfer‐reaction mass spectrometry (PTR-MS): An analytical method enabling real-time detection and quantification of trace VOCs.

Hydroxyl radical reactivity (OH reactivity): The total reactive sink strength of atmospheric constituents towards the hydroxyl radical, a key determinant of VOC oxidation rates.

References

1. Secondary organic aerosol association with cardiorespiratory disease mortality in the United States. Nature Communications (2021).
2. Comparison between Spatially Resolved Airborne Flux Measurements and Emission Inventories of Volatile Organic Compounds in Los Angeles. Environmental Science and Technology (2023).
3. Two years of volatile organic compound online in situ measurements at the Site Instrumental de Recherche par Télédétection Atmosphérique (Paris region, France) using proton-transfer-reaction mass spectrometry. Earth System Science Data (2023).