Ultraviolet irradiance over Mexico City

Abstract

This article compiles and analyzes information on the interaction of both ground-level ultraviolet radiation and anthropogenic ozone in the extremely polluted atmosphere of Mexico City. Simultaneous anthropogenic ozone and globalflux (sun and sky) measurements were recorded in nearultraviolet radiation (295-385 nm) for a 30-month period (March 1990 to August 1992). Results reveal that under clearsky conditions, high concentrations of ozone (and presumably of other pollutants) impede UV-fluxes from reaching their maximum values. Furthermore, heavy cloud cover causes ozone concentrations to reach their minimum values together with UV-minimum fluxes. Seasonal variation in UV-irradiance is also discussed. Findings indicate that maximum UV-fluxes occur in spring and summer and thatminimum values occur in autumn and winter. Significant daily local reductions in UV-fluxes (up to 50%) during afternoon hours in Mexico City can be attributed to air pollution. Finally, the growing incidence of rickets in children residing in the Mexico City metropolitan area may be related both to dietary deficiencies and to the UV-flux depletion on the ground. © 1995 Taylor & Francis Group, LLC.