1. PM10 gravimetric measurements in the MCMA were collected using Sierra Anderson Model 1200 size selective inlet high-volume gravimetric samplers (EPA Reference Method RFPS-1287-063).
2. The criteria air pollutants are particulate matter, ozone (and other photochemical oxidants), sulfur dioxide, carbon monoxide, nitrogen dioxide and lead. This designation originates in the US Clean Air Act and is intended to include pollutants emitted from numerous sources across the country which are reasonably anticipated to endanger public health. See Chapter 1, Section 4.1.1.
3. 1998 GNP per capita was $3,970 in Mexico and $29,340 in the US (The World Bank, Entering the 21st Century: World Development Report 1999-2000, Oxford University Press, New York).