In an air-handling system that provides cooled air to occupants of a building, most of the air is returned from the space back to the air handler to be reused. This is called â¦ Return Air, or RA. However, some fresh air (called Outside Air, or OA) must be mixed in.
Polio is a viral infection that can cause permanent paralysis. The inactivated poliovirus vaccine (IPV) is usually given at ages 2 months, 4 months, 6â18 months, and 4â6 years. Though the oral poliovirus vaccine (OPV) is still used in many parts of the world, it has not been used in the United States since 2000.
The poliovirus vaccine used in the United States is IPV. IPV is a shot, given in the leg or arm, depending on age. Polio vaccine may be given at the same time as other vaccines. IPV is routinely given to children. Children get 4 doses at these ages: 1  A dose at 2 months.2  A dose at 4 months. 3  A dose at 6-18 months.he poliovirus vaccine used in the United States is IPV. IPV is a shot, given in the leg or arm, depending on age. Polio vaccine may be given at the same time as other vaccines. IPV is routinely given to children. Children get 4 doses at these ages: 1  A dose at 2 months.