What is the minimum oxygen percentage for Grade D air?

The minimum oxygen percentage for Grade D air is defined as 19.5%. Grade D air is specifically regulated for respiratory protection and is required to have a minimum oxygen content to ensure safety during respiratory exposure. This specification is crucial for environments where asphyxiation risk exists, as a higher concentration of oxygen is essential for human vitality and cognitive function.

Having oxygen levels at or above this threshold helps to mitigate risks associated with lower oxygen environments, such as dizziness, unconsciousness, and even fatalities. The distinction that 19.5% is the minimum requirement emphasizes the importance of maintaining adequate air quality in various confined or hazardous atmospheres encountered in occupational settings, particularly where asbestos or other harmful materials may be present.