Characterization of cooking aerosol through an ensemble of measurements targeting chemical composition, physical properties and oxidative potential.

Cooking, one of key human activities, has been known to contribute significantly to ambient aerosol in both the indoor and outdoor settings. In certain urban environments, cooking Organic Aerosol (OA) have been documented to drive outstanding smog events. On the other hand, more research is necessary on induced health effects by such aerosol. A controlled, cooking and grilling experiment was performed in June 2024 in an effort to physically and chemically characterize cooking aerosol and derive estimations on their oxidative potential. Along the way, the response of the Aerosol Chemical Speciation Monitor (ACSM) to direct cooking emissions was assessed, while reference single source mass spectra were acquired, to be used as an important aid for constraining algorithms performing source apportionment of ambient aerosol. Various cooking conditions (gas vs charcoal grill, frying pan) were tested on different types of food (vegetables, steaks, burgers, chicken, fish, fries, etc). The experimental setup included an ACSM, a 7-wavelength filter-based absorption photometer (AE-33 aethalometer), a Scanning Mobility Particle Sizer (SMPS) providing number size distributions and filter sampling of PM_2.5 aerosol to perform off line detailed composition analysis and oxidative potential estimates.

                Acquired OA mass spectra presented similarities, being dominated by prominent signals at m/z = 41, 43, 55 and 57, linked to the fragmentation of alkyls and specifically the C_nH_2n+1 and C_nH_2n-1 ion series. All cooking spectra acquired, share the common feature of an m/z = 55 over m/z = 57 contribution ratio (i.e. f₅₅/f₅₇) well above unity. The contribution of significant signal at m/z = 60, a typical tracer of the fragmentation of levoglucosan, related to the pyrolysis of cellulose was evident in the mass spectra of charcoal grilled food. Interestingly non negligible, nevertheless low contributions at m/z = 60, were also found for food cooked on a gas burner grill. Grilling vegetables yields pronounced contributions at higher m/z values (e.g. for m/z =67, 69, and 71). The largest contribution at m/z = 44 in the mass spectrum, was observed when sampling aerosol from burning the residual fat from a heated pan.

Acknowledgement: This work is supported by the European Union's Horizon Europe research and innovation programme under the Marie Skłodowska-Curie Postdoctoral Fellowship Programme, SMASH co-funded under the grant agreement No. 101081355. The SMASH project is co-funded by the Republic of Slovenia and the European Union from the European Regional Development Fund.