Tropical inhabitants are able to tolerate heat through permanent residence hot and often humid tropical climate, to clarify the peripheral mechanisms of the thermal sweating in pre-post exposure by sweating responses to acetylcholine (ACh), a primary neurotransmitte of the sudomotor functions were healthy subjects (n=8). ACh was iontophoretically 10% iontophoresis administered on the inner forearm skin. Directly activated and axon reflex-mediated sweat responses were evaluated by quantitative sudomotor axon reflex test. The AXR sweat onset-time (axon reflex) was 1.62±0.82 min and 1.24±0.62 min in human subjects by pre-post exposure, respectively (P＜0.001). The AXR(1) sweat volume (axon reflex) was 1.25±0.75 ㎎/㎠ and 2.08±0.85 ㎎/㎠ in human subjects by pre-post exposure, respectively (P＜0.001). The AXR (2) sweat volume (axon reflex) was 2.03±0.65 ㎎/㎠ and 3.05±0.72 ㎎/㎠ in human subjects by pre-post exposure, respectively (P＜0.001). The DIR sweat volume (directly activated) was 4.96±1.38 ㎎/㎠ and 5.68±1.27 ㎎/㎠ in human subjects by pre-post exposure, respectively (P＜0.001). Activated sweat volume in the sudomotor functions was higher the output for the post-exposure than the output for the output pre-exposure. It was concluded that the post-exposure had the higher sweat output due to the combination of the higher sweat volume and the shorter of onset time. In conclusion, higher sudomotor responses to ACh receptors are indicative of accelerated sympathetic nerve responsiveness to ACh sensitivity by exposure environmental condition.