Did extreme environmentalism contribute to the Columbia's demise? The Freon foaming agent for the spray-on foam insulation used on the shuttle's main fuel tank changed in the mid 1990s when a concern was raised about the Freon's affect on the ozone layer. Freon worked perfectly and without a separation failure since the inception of the shuttle program. The new foaming agents use water and pentane, which traps moisture and subsequently weakens the foam's adhesion to the primer on the surface of the fuel tank. The problem is exacerbated at high altitudes due to trapped gas expansion in the foam's cells. Numerous instances of foam swelling and breaking off has been reported since the switch. A separated piece of foam that struck the left wing leading edge at takeoff is the prime suspect for causing the Columbia's reentry breakup on February 1, 2003.