What is a heifer cow? A heifer is a mature female cow that has not calved, or given birth to a calf, yet. As soon as a heifer gives birth, she becomes a cow. A cow refers to a female of any age that has given birth.
When most people think about gas masks or respirators, what they usually envision is a tight-fitting plastic or rubber face mask with some sort of filter cartridge. The mask covers the nose and mouth. These are called half-mask air-purifying respirators.
â¢ Masks o Properly fitted masks must be used when there is a risk of exposure to an uncontained amount of cytotoxic agent or when there is risk of aerosolization of cytotoxic drugs (N95 masks meeting NIOSH respiratory protection standards).