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In this work, we report the economic impact of exposure to high ozone concentrations on four important crops in the area of influence of the Mexico City Megalopolis. Estimated yield losses were as follows: maize: 3%; oats: 26%; beans: 14%; sorghum: 15%. The information needed to estimate the impact of air pollution in Mexico is decidedly deficient. Regarding ozone, the coverage provided by the monitoring networks is strongly focused on urban monitoring and its consistency over time is highly irregular. Apart from the Mexico City Metropolitan Area (MCMA) and less than a handful of other cities, the quality of the data is poor. Ozone in rural areas can be estimated with air quality models. However, these models depend on a high-resolution emissions inventory, which has only been done through validation processes in the MCMA. With these limitations, we set out to estimate the economic impact of exposure to ozone in these crops with a varying degree of sensitivity to ozone in the city belt of Central Mexico. To this end, we developed a procedure that makes optimal use of the sparse information available for construction of AOT40 (accumulated exposure over the threshold of 40 ppb) exceedance maps for the 2011 growing season. We believe that, due to the way in which we dealt with the sparse information and the uncertainty regarding the available data, our findings lie on the safe side of having little knowledge such that they may be useful to decision-makers. We believe that this procedure can be extended to the rest of the country, and that it may be useful to developing countries with similar monitoring and modeling capacities. In addition, these impacts are not evenly distributed in the region and sometimes they were greater in municipalities that have a higher index of poverty. Air pollution arriving from urban areas increases the social inequalities to which these already vulnerable populations are exposed.

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Palabras clave: nitrato de peroxiacetilo, contaminación fotoquímica, monitoreo atmosférico, Valle de México. RESUMENSe midieron los contaminantes nitrato de peroxiacetilo (PAN) y dióxico de nitrógeno (NO2, verdadero) durante dos campañas cortas de monitoreo en junio y octubre de 2017 con un método por cromatografía de gases y detección por luminol al suroeste de la Ciudad de México. Los promedios horarios máximo y total de la razón de mezcla medida del PAN de cada campaña fueron de 5.2 y 1.3 ppbv en junio y de 3.3 y 0.6 ppbv en octubre, respectivamente, ligeramente menores a los promedios reportados en 2003. Esto sugiere que la emisión de precursores de este contaminante: acetaldehído y butenos, han disminuido sólo parcialmente en los últimos 15 años. Los promedios horarios del PAN fueron correlacionados con O3 y NO2 (medido por quimioluminiscencia), radiación solar, temperatura, e intensidad del viento registrados en el mismo sitio para obtener un modelo empírico combinado (MEC) para el diagnóstico aproximado de las concentraciones del PAN para otros periodos del año. El MEC resultante se integró con varias correlaciones lineales múltiples que se aplican dependiendo del periodo del día y la temperatura. La correlación entre el PAN simulado y el medido para las dos campañas resultó en un coeficiente R 2 = 0.87. Se aplicó el MEC a registros de las variables antes