Forecasting Human Exposure to Atmospheric Pollutants in Portugal

Air pollution has become one main environmental concern because of its known impact on human health. Aiming to inform the population about the air they are breathing several air quality modelling systems have been developed and tested allowing, nowadays, assessing and forecasting air pollution ambient levels in many countries. However, every day, one individual is exposed to different concentrations of atmospheric pollutants as he/she moves from and to different outdoor and indoor places (the so-called microenvironments). Therefore, a more efficient way to prevent the population from the health risks caused by air pollution should be based on exposure rather than air concentrations estimations. The present study describes the development of a methodology to forecast the human exposure of the Portuguese population, which is based on air quality forecasts available and validated for Portugal since 2005. To estimate the population exposure the forecasting results of the air quality modelling system MM5-CHIMERE have been combined with the population spatial distribution over Portugal and their time-activity patterns, i.e. the fraction of the day time spent in indoor and outdoor places. The population characterization concerning age, work, type and spent time on occupation/activities, was obtained from the most recent national census and from available enquiries performed by the National Statistics Institute. A daily exposure estimation module has been developed gathering all these data and considering empirical indoor/outdoor relations from literature to calculate the indoor concentrations in each one of the microenvironments considered, namely home, office/school, and leisure activities like shopping areas, gym, theatre/cinema and restaurants. The results show how this developed modelling system can be useful to anticipate air pollution episodes and to estimate their effects on human health. This detailed knowledge is a prerequisite for the development of effective policies to reduce the foreseen adverse impact of air pollution on human health and to act on time.