MSC Chief of Center Medical Programs Charles A. Berry reported that the cause of the three astronauts' deaths could be refined to asphyxiation from inhalation of carbon monoxide, bringing unconsciousness in seconds and death rapidly thereafter. The astronauts were believed to have become unconscious 18 to 20 seconds after the fire began.
Associate Administrator for Manned Space Flight George E. Mueller said NASA was introducing a three-pronged effort to prevent fire in the future: it would continue to minimize the possibility of ignition but would recognize the possibility would always exist, would seek to eliminate the chance of propagation if a fire began, and would seek to minimize consequences of a fire to the crew. Newly developed nonflammable materials would be used wherever possible and would be arranged to maintain fire breaks. Systems would be made more fire- and heat-resistant. The new CM cabin would be verified by full boilerplate flame tests. Design work was under way on a new unified hatch - a single integrated hatch to replace the double hatch and permit emergency exit in two seconds, yet remain safely sealed in flight. Emergency procedures were being revised. Spacecraft system design and qualification were being thoroughly reviewed. Alternative cabin atmospheres for checkout and launch were being studied, but during flight itself pure oxygen at 3.5-newtons-per-square-centimeter (5-pounds-per-square-inch) pressure still appeared safest for crews, with best balance among fire hazard, system reliability, and physiological risks.
First Apollo Block II spacecraft - CSM 101, the next in line at North American Aviation - was to incorporate all changes determined necessary by the investigation.