Gaseous Chloramine Production and Outdoor Transport From a Commercial Kitchen and Athletic Facilities

Reactive nitrogen species (N_r), defined here as all N-containing compounds except N₂ and N₂O, have been shown to be important drivers for indoor air quality. Key species including NO_x, HONO and NH₃, are known to have detrimental health effects. In addition, other N_r species such as amines that are not traditionally measured may be important chemical actors for indoor transformations. Cooking and cleaning are significant sources, with variable emissions depending on activity type and materials. During the start up of a commercial kitchen - from closure during the pandemic to resuming service for more than 500 meals per day in catering and a la carte orders - we measured the composition of the indoor air with a custom-built instrument to quantify the total gas-phase reactive nitrogen (tN_r) budget and also quantified pools within this including: NO_x, HONO, and NH_x. Supporting VOCUS-PTR-MS and a suite of standard gas phase pollutant (NO_x, O₃, CO₂) measurements allowed identification of important but previously unrecognized indoor Nr, in the form of chlorinated amines. Logs of kitchen cooking and cleaning activities were used to isolate sources of the observed species, while ventilation and resuming of kitchen activities provided insight into the impact of sustained use of the indoor space on the budget and composition of tNr. The observed chloramines were dominated by monochloramine (NH₂Cl) on the order of several ppbv alongside substantial enhancements in fine particulate matter (PM_2.5) mass loadings. Emissions of NH2Cl from production on cleaned surfaces were observed to be rapidly removed from the space in the presence of effective air change rates (ACR) which could reach the order of 30 hr-1. Similar observations were made during cleaning of an indoor athletic facility, suggesting that chlorine activation and Nr chemistry are intimately linked indoors. There are potential impacts of ventilated chloramines on outdoor air, should they release Cl atoms upon photolysis or enter the condensed phase. Outdoor observations downwind of an athletic centre in Leicester, UK found appreciable levels of NH₂Cl impacting the local atmosphere, but fundamental knowledge on gaseous transformations limited a comprehensive understanding of atmospheric impacts. Quantitative determinations of the chloramine family remains a challenge.