  Open-path dual-comb spectroscopy provides multi-species atmospheric gas
concentration measurements with high precision. Here, we extend open-path dual
comb spectroscopy to the mid-infrared 5 {\mu}m atmospheric window, enabling
atmospheric concentration retrievals of the primary greenhouse gases, N$_2$O,
CO$_2$, and H$_2$O as well as the criterion air pollutants O$_3$ and CO across
600 m and 2 km round-trip paths. We demonstrate measurements over a five-day
period at two-minute temporal resolution with 80% uptime. The achieved
precision is sufficient to resolve the atmospheric concentration variations of
the multiple gas species; retrieved dry mixing ratios of CO and N$_2$O are in
good agreement with a co-located point sensor. In addition, the retrieved ratio
of excess CO vs CO$_2$ agrees with similar urban studies but disagrees with the
US National Emission Inventory by a factor of 3. Our retrieved ratio of excess
N$_2$O vs CO$_2$ exhibits a plume-dependent value, indicating the variability
of sources of the greenhouse gas N$_2$O.
