Abstract View
Characterization and Variability of Urban Cooking Emissions Sources
SUNHYE KIM, Jo Machesky, Drew Gentner, Albert A. Presto, Carnegie Mellon University
Abstract Number: 357
Working Group: Urban Aerosols
Abstract
Primary aerosols, including cooking organic aerosol (COA) constitute a minority of total PM2.5 mass on average, however, their fresh emissions dominate intra-city spatial variations in PM2.5 concentrations and exposure. This study focuses on characterizing the variability of COA composition using a mobile laboratory to measure fresh cooking emissions from 9 restaurants in two cities. We quantified particle size distributions and number concentrations with a fast mobility particle sizer (FMPS) and condensation particle counter (CPC) and COA mass and composition with an aerosol mass spectrometer (AMS). Particle number concentrations and size distributions emitted from the restaurants studied were highly variable. These concentrations varied maximally by 100-fold over 50 minutes from some restaurants, likely due to on-demand cooking activities as food orders were placed. The mode diameter of particles was ~10.08 nm, suggesting that restaurant cooking is a major source of ultrafine particles in urban areas.
The overall AMS mass spectra of our samples strongly correlated with typical cooking emissions measured in the laboratory and to ambient COA factors derived via factor analysis (R>0.8 and θ<20°). However, emissions from a commercial bakery demonstrated exceptional chemical features that were unreported in prior literature with lower correlations (θ=45°-83°, R=0.03-0.67). The AMS analysis suggests that bakery samples had distinctive N-containing fragmentation ions (m/z 58 C3H8N+, m/z 86 C5H12N+, and m/z 100 C6H14N+).
These reduced-nitrogen containing peaks were also detected at other cooking sites which likely include bread as part of their menu. To examine potential sources of the nitrogen features in the laboratory, we measured emissions with and without the dough stabilizer azodicarbonamide (C2H4N4O2) as a possible source of N-containing peaks. However, the reduced nitrogen peaks were not detected, suggesting that another by-product of bread production is the source of these nitrogen-containing species.