Emission factors from urban food systems in a circular city

Urban Agriculture (UA) plays a crucial role in building resilient and sustainable cities by ensuring a steady food supply and offering environmental, economic, and societal benefits. Despite its potential, implementing UA, which includes Rooftop Greenhouses (iRTGs) and Vertical Farms (VFs), faces challenges such as air quality concerns and regulatory issues. Indoor pollution, particularly Volatile Organic Compounds (VOCs), poses health risks, and the expansion of UA installations is expected to increase biogenic VOCs (BVOCs) emitted by plants. Monitoring BVOC emissions is essential to understand their impact on air quality and human health. Research conducted in a building iRTG and an indoor VF assessed BVOC emissions from plants like green beans, tomatoes, and basil. The study aimed to define safety thresholds for BVOC emissions, considering factors influencing emissions and potential health risks. BVOC levels remained within safe limits on average, peaking during initial growth phases and decreasing later. In iRTGs, monoterpenes dominated early emissions, followed by lipoxygenase derivatives and oxygenated monoterpenes, while in VFs, emission patterns varied with light treatment. Safety assessments compared BVOC concentrations against indoor limits set by regulatory bodies, showing that emissions from UA spaces were significantly lower than reference limits. Environmental factors such as temperature, humidity, CO2 concentration, and lighting significantly influenced BVOC emissions, with artificial lighting playing a crucial role in VFs. Plant morphology also affected emissions, with variations observed across growth stages. Various volatile sampling techniques were employed, with active sampling in a static enclosure preferred for its reliability and accuracy. Alternative approaches using different sorbent materials and analytical techniques yielded consistent findings, showing technical advancements in BVOC sampling. Future research could explore additional plant species, alternative fertilizers, and new sampling methods to enhance outcomes and understand BVOCs' positive effects on agronomic development and UA expansion.