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.
Is a surgical mask an N95 respirator? No. Surgical masks are not designed for use as particulate respirators and do not provide as much respiratory protection as an N95 respirator. Surgical masks provide barrier protection against droplets including large respiratory particles.