ratio map. One can note that polycyclic aromatic hydrocarbon (PAH) emission at 3.3 $\mu$m is included in the IRAC 3.6 $\mu$m band, and a prominent molecular hydrogen line emission ($\nu$ = 0–0 $S$(9); 4.693 $\mu$m) is covered in the IRAC 4.5 $\mu$m band. Hence, the regions with the excess of 4.5 $\mu$m emission (i.e., bright regions) appear to trace the outflow activities in AFGL 5157, which are distributed toward the IRDCs. This argument is supported by the fact that the bright regions in the ratio map are spatially matched with the positions of MHOs (see Figure \[fig1\]f), which are driven by YSOs [e.g., @chen03; @wolf17]. We also find that the bright regions in the ratio map and the positions of MHOs are found mainly toward the IRDCs or the sub-mm 850 $\mu$m continuum peaks, depicting the locations of ongoing SF in AFGL 5157. Taking into account the inclusion of 3.3 $\mu$m PAH feature in the 3.6 $\mu$m band, the boundaries of the shell-like feature hosting the diffuse H$\alpha$ emission seem to trace photodissociation regions (or photon-dominated regions, or PDRs). In the Galactic northern direction, the observed diffuse 8.0 $\mu$m emission also hints the presence of an extended PDRs in the 