The permissible exposure limit (PEL) for chlorine is:

The permissible exposure limit (PEL) for chlorine being set at 0.5 ppm is grounded in health and safety regulations aimed at protecting workers from exposure to hazardous chemicals. This limit represents an averaged concentration of chlorine in the air that workers can be exposed to over an 8-hour workday without experiencing adverse health effects.

Chlorine is a potential irritant to the respiratory system and skin, and higher concentrations can lead to serious health hazards, including respiratory distress and damage. The PEL is established based on studies and recommendations from organizations such as OSHA (Occupational Safety and Health Administration), which conducts assessments regarding safe exposure levels in occupational settings.

By setting the PEL at 0.5 ppm, it ensures that there is sufficient margin to protect workers while allowing the use of chlorine in industrial applications, such as water treatment and chemical manufacturing. A lower limit would potentially hinder operations that require the use of chlorine, whereas a higher limit could increase the risk of adverse health effects.