Chlorine is EXTREMELY HAZARDOUS, with an IDLH of 10 ppm and a TLV of 0.5 ppm (just above the odor threshold for most). Chlorine is heavier than air (VD > 2.5), and when released, it forms a greenish-yellow gas with a pungent, irritating odor that follows the terrain at ground level. The mean odor threshold...