Presented below are some detailed photos of a BioHazard Suit Helmet used in the 1st season TOS episode "The Naked Time" (first airdate: Sept. 29, 1966). Star Trek Costume Designer William Ware Theiss, perhaps most well remembered for outfitting the many female guest stars of TOS in daring and revealing alien dresses and wardrobe, relied on primarily orange shower curtain fabric for the creation of this helmet. Some episodes screenshots featuring the costume are shown following the modern day images. 
A complete BioHazard Suit as displayed in February, 2009 at the Detroit Science Center as part of the Star Trek: The Exhibition tour...
Some episode screenshots from "The Naked Time" ...
Monday, August 23, 2010
TOS BioHazard Suit Helmet from "The Naked Time"
