Table shows the enhancement ratio due to these nearby emission events (ERnearby) at different locations, and Figure shows the corresponding time series. When the simulation is done at a 4 km resolution, nearby emission events only increase local column concentrations at location c by 9%, on average. This average value goes up to 11% when the simulation is performed with a 1.33 km resolution. With the same resolution, ERnearby exceeds 2 in only 1.3% of all the simulation hours. ERnearby is even lower when the time period for analysis is restricted to daylight hours (0.9%) or in the 1300-1400 hour time period (0.9%). These results suggest the interference from nearby emissions events is not a dominant contributor to overall background levels.