The step in which reactant escape from the surface into the gas phase is known as desorption
Desorption is a phenomenon whereby a substance is released from or through a surface. One substance is released from another either from the surface or through the surface. Desorption can occur when the system is in the state of sorption equilibrium between bulk (fluid) and adsorbing surface.( boundary separating two fluids) uds )
The sign that would make me call 911 is his pulse. If the child's pulse is unresponsive, then that would be a clear sign for me to call the paramedics.