There are significant differences in international health care ventilation standards. This paper is part one of two reviewing those variances. This paper compares minimum ventilation requirements for operating rooms, procedure rooms, and birthing spaces. The standards compared are (1) ASHRAE-170 Ventilation for health care facilities (US), (2) DIN-1946 - VAC systems in buildings and rooms used in the health care sector (Germany), (3) HTM-03-01 Specialized ventilation for health care premises (UK), and (4) UNE 100713 Instalaciones de acondicionamiento de aire en hospitales (Spain). The comparison identifies the minimum (i.e. most permissive) ventilation requirements in six different requirement areas: outdoor air ventilation, total room air ventilation, supply air filter efficiency, room temperature, room humidity, and room pressurization. Results are normalized to common units, and compared.