Received April 30, 1998
Accepted October 17, 1998

During in vitro fertilization procedures, the sperm cells, oocytes and embryos are in direct contact with ambient air. This contact happens during aspiration, in the laboratory and transfer. Ambient air can contain many types of contaminants that can be introduced in the culture system. Embryos present a transport system where passive and active absorption mechanisms are mostly indiscriminants as they do not posses a defensive system. This effect is cumulative and acts diminishing implantation rates. Measures to minimize these contarninants in laboratory and incubator air are proposed.