A personal protection system comprising a head unit configured for use with a hood that includes a transparent, flexible face shield and the hood, said head unit including: a support structure (272, 286, 428, 430) for supporting the hood around the head of a wearer; a fan attached to the support structure for drawing air through the hood; and support structure mounting means (296, 524) integral with the support structure (272, 286, 428, 430), the support structure mounting means (296, 524) adapted to engage complementary face shield mounting means (594, 596) for removably securing the hood over the head unit so that the face shield is located forward of the face of the wearer and is curved around the face of the wearer; and said hood including: a covering shaped to fit over the head of the wearer and the support structure of the head unit disposed over the head of the wearer; and a transparent face shield formed from flexible material that is attached to said covering; and hood mounting means (594, 596); the personal protection system characterized in that: the support structure mounting means (296, 524) are arranged so that, when the support structure mounting means engage the face shield mounting means (594, 596), the radius of curvature of the face shield varies along a top to bottom longitudinal axis of the face shield such that a top section of the face shield has a first radius of curvature and a bottom section of the face shield has a second radius of curvature smaller than the first radius of curvature. said head unit including: a support structure (272, 286, 428, 430) for supporting the hood around the head of a wearer; a fan attached to the support structure for drawing air through the hood; and support structure mounting means (296, 524) integral with the support structure (272, 286, 428, 430), the support structure mounting means (296, 524) adapted to engage complementary face shield mounting means (594, 596) for removably securing the hood over the head unit so that the face shield is located forward of the face of the wearer and is curved around the face of the wearer; a support structure (272, 286, 428, 430) for supporting the hood around the head of a wearer; a fan attached to the support structure for drawing air through the hood; and support structure mounting means (296, 524) integral with the support structure (272, 286, 428, 430), the support structure mounting means (296, 524) adapted to engage complementary face shield mounting means (594, 596) for removably securing the hood over the head unit so that the face shield is located forward of the face of the wearer and is curved around the face of the wearer; and said hood including: a covering shaped to fit over the head of the wearer and the support structure of the head unit disposed over the head of the wearer; and a transparent face shield formed from flexible material that is attached to said covering; and hood mounting means (594, 596); a covering shaped to fit over the head of the wearer and the support structure of the head unit disposed over the head of the wearer; and a transparent face shield formed from flexible material that is attached to said covering; and hood mounting means (594, 596); the personal protection system characterized in that: the support structure mounting means (296, 524) are arranged so that, when the support structure mounting means engage the face shield mounting means (594, 596), the radius of curvature of the face shield varies along a top to bottom longitudinal axis of the face shield such that a top section of the face shield has a first radius of curvature and a bottom section of the face shield has a second radius of curvature smaller than the first radius of curvature.