Planning for Air Quality Concerns of the Future

— In recognition of growing needs for forecasts of air quality and atmospheric deposition to accompany classical weather forecasts, a new generation of atmospheric prediction models is slowly evolving. These share the common feature that atmospheric chemistry will be directly incorporated into advanced forecast schemes. It is argued that in most practical applications, the over-riding need is not for accurate prediction of some quantifiable air quality component, but rather a forecast of the probability of harmful consequences to exposure. In this event, it is not concentrations that need to be forecast, but the probability that concentrations will exceed some predetermined level at which consequences could be harmful. This argument extends from emergency response applications to ecosystem decline.