Is it safe to enter a permit-required confined space wearing an air purifying respirator if gas tests show the atmosphere has an oxygen level of 19.0%?

The correct answer is that it is not safe to enter a permit-required confined space while wearing an air-purifying respirator when the oxygen level is measured at 19.0%. This oxygen concentration is below the normal atmospheric level of approximately 20.9%. While 19.0% may seem relatively close to normal, it is still considered insufficient for safe breathing, as the lower oxygen concentration could potentially impair physical and cognitive functions.

Moreover, air purifying respirators are not designed to supply oxygen; instead, they filter harmful contaminants from the air. In an environment where oxygen levels are already below a safe threshold, relying on such devices would not provide adequate protection. Therefore, entering a confined space with this oxygen level poses significant risks, including the likelihood of causing asphyxiation or other severe health issues.

Safe entry into confined spaces typically requires ensuring that there is an adequate atmosphere with oxygen levels at or above 19.5% for safe breathing, along with appropriate monitoring and safety measures in place.