Pathways for the oxidation of sarin in urban atmospheres

The nerve agent sarin has recently been deployed by terrorists in a major c ity. The molecule is volatile and made its way to many victims by passing a s vapor through a highly reactive medium. Here we estimate rates and pathwa ys for the removal of gas phase sarin from a generalized urban atmosphere. Only information from the open scientific literature is used. By structure reactivity comparisons with the organophosphorus pesticides, hydroxyl radic al hydrogen abstraction may occur in as little as one hour. Decomposition o f side chains after hydroxyl attack leads to organic oxygenates which prese rve the phosphono-fluoridate and so toxicity. The aqueous aerosol surface i s contacted in minutes and offers access to a range of dissolved nucleophil es. Substitution displaces the fluoride leaving group, giving safe phosphor ic acid analogs. Because of uncertainties in the electron distribution and in aqueous decay mechanisms, the time constants must be viewed as lower lim its.