Quantification error of mobile solutions (left) and continuous monitoring solutions (right) for detected emission sources. Mobile methods produced quantification estimates that averaged 17% higher than the mean actual emission rate in testing, while continuous monitoring solutions had a more substantial overestimate of emissions, 167% higher than the mean actual emission rate. Quantification error of individual solutions (anonymized and shown as lighter lines) illustrate individual performance may be biased lower or higher (shifted left or right) from performance of all solutions. DOI: https://doi.org/10.1525/elementa.426.f5