At what ppm range does chlorine become extremely unsafe?

Chlorine is commonly used as a disinfectant in water treatment, but its safety is highly dependent on concentration levels. At concentrations above 2.0 ppm, chlorine can become extremely unsafe for both human health and aquatic life. Exposure to high levels of chlorine can cause respiratory issues, eye irritation, and skin problems. Additionally, it can lead to harmful byproducts, especially in the presence of organic matter, which can further compromise water quality.

In contrast, the lower ranges, such as 0.1 - 0.3 ppm, 0.5 - 1.0 ppm, and 1.0 - 2.0 ppm, are generally considered to be acceptable for disinfection purposes. Although there may be some health concerns associated with prolonged exposure even at these levels, they are manageable and often used in practice. Recognizing the critical threshold above 2.0 ppm reinforces the importance of careful monitoring and management of chlorine levels in water treatment to ensure safety.