Emissions from Washington State Compost Facilities: A Review of Volatile Organic Compound Data, and an Estimation of Greenhouse Gas Emissions

This report analyzes volatile organic compound (VOC) data collected from six Washington compost facilities and examines implications for air quality, permitting, and greenhouse gas emissions. Light alcohols and monoterpenes dominated measured emissions, but inconsistent laboratory methods and the absence of measurements across a complete composting cycle prevented development of a reliable Washington-specific emissions factor. Using California factors, the authors estimated that seven Washington facilities could potentially exceed the 100-ton annual VOC threshold for federal Title V permitting, although the applicability of those factors remains uncertain. The report recommends improved sampling capable of measuring both light alcohols and monoterpenes throughout pile development. A separate EPA model comparison found that diverting food waste from landfills to composting would likely reduce greenhouse gas emissions, largely by avoiding landfill methane and storing carbon when compost is applied to soil.