Trends in atmospheric concentrations of lead in the metropolitan area of Mexico city, 1988-1998]

Objective. To describe the trends in airborne lead levels and their association with the control measures implemented from 1988 to 1998 to phase out lead from gasoline that included the introduction of a lead-free gasoline and the use of catalytic converters in automobiles in Mexico City. Material and Methods. Data of atmospheric lead levels were obtained from the 9 field stations included in the local air quality monitoring network (RMMA). Trends for airborne lead are shown by monitor, monitoring area and for the entire metropolitan zone. Analysis of data was performed using linear regression models including auto-correlation analysis. The models were validated by standard diagnostic techniques using student residuals analysis. Results. The introduction of lead-free gasoline and the use of catalytic converters decreased the airborne lead levels by 23% while the slow elimination of lead from gasoline produced a cumulative decrease of 89% during the period and in all areas studied. Conclusions. The strategy implemented to reduce sources of airborne lead pollution had an important impact on atmospheric lead levels. Health risks of this environmental hazard are now primarily due to less important sources and to particular occupational exposures. The English version of this paper is available at: http:// www.insp.mx/salud/index.html.