Air quality as a meteorological hazard

Meteorological hazards are usually considered to be tropical cyclones, drou ghts, hail-storms, severe storms and their effects such as tsunamis, storm surges, wildfire, and floods. Urban air pollution is not normally considere d to be a meteorological hazard. This view has arisen because the causes of urban air pollution - industrial and motor vehicle emissions - are not met eorological in nature. Air pollution episodes, however, are sporadic in nat ure and their occurrence depends on a particular combination of meteorologi cal factors. This is true even in megacities such as Mexico City, Manila, a nd Los Angeles that have acquired a reputation for polluted air. Analyses o f air pollution episodes and hospital admissions from many countries indica te that there is a significant increase in morbidity and mortality as a res ult of such episodes. Time-series studies undertaken in Sydney have shown t hat particulate matter, ozone and nitrogen dioxide are the pollutants that are primarily responsible for adverse health effects in that city. Air pollution, and in particular particulate matter, is believed to be resp onsible for just under 400 premature deaths per year in Sydney alone. This death rate is over twenty times larger than deaths due to other meteorologi cal hazards. Part of the reason for the low death rate for the more traditi onal meteorological hazards is that the provision of high quality numerical weather prediction, coupled with modern communications technology, has ena bled emergency service personnel to take appropriate action. Air quality forecasting systems can play an important role in mitigating th e adverse effects of air pollution. The forecasts will affect the behaviour of susceptible individuals, and thus reduce adverse health effects. The ou tputs from forecasting systems can also be used to provide improved estimat es of the total exposure to air pollutants of the inhabitants who are at ri sk. Such improved estimates can then be used in conjunction with longitudin al studies of health effects to obtain better understanding of the complex interaction between air quality and health.