F. Sánchez-Sinencio

Atmospheric pollution profiles in Mexico City in two different seasons

A CO2-laser-based photoacoustic spectrometer was used to determine the temporal concentration profile of atmospheric ethene in Mexico City. Ethene measurements were conducted at the facilities of our institute, which is located in the north of the city and next to an avenue with heavy traffic density. Ambient air from outside our laboratory was continuously pumped into the spectrometer. This campaign was performed for 24 h a day, from November 24–30, 2001. The maximum ethene levels ranged between 26 and 81 ppbV. As expected, the lowest concentrations were monitored on weekends. These data were analyzed in combination with ozone and nitrogen oxides profiles, which were permanently monitored by an air-pollution-monitoring government network. Information on the seasonal variability of ethene was obtained by comparing the results of this campaign with data obtained in the winter of 2001. In general, the ethene concentration in November was about 30% higher than in February. On weekdays, the mean dose of human...

CO2 laser photoacoustic spectroscopy applied to environmental analysis in the metropolitan area of Mexico city

Abstract Measurements of atmospheric ethene were performed in the Metropolitan Area of Mexico City by means of a 12C16O2 laser‐based photoacoustic spectrometer. Two types of experimental campaigns were conducted. In the first type, performed in November 1999 and March 2000, air samples were simultaneously collected in canisters during the morning (06:00 to 09:00 h) in Xalostoc (industrial site), La Merced (commercial site), and Pedregal (residential site). The highest ethene levels were usually detected in Xalostoc, followed by those in La Merced and Pedregal. In the second type of campaign, carried out in March 2002, real‐time ethene measurements were performed at the facilities of our institute (CINVESTAV) by continuously drawing ambient air to the photoacoustic spectrometer. Typically, the ethene concentration exhibited two broad bands daily, reaching up to 104 ppbV at around 07:10 h. Ethene levels were also studied as a function of nitrogen oxide data obtained from a government network for atmospheric monitoring, and a linear correlation between ethene and NOx concentrations was found. Finally, the ethene levels in Mexico City were compared with those measured in other cities worldwide.