J. Lartigue

Long term and equilibrium factor indoor radon measurements

This paper presents the annual radon gas concentrations obtained during the 1994–1995 monitoring campaign using passive electret system (type E-PERM). Radon levels were measured in 154 single family dwellings, in normal occupancy conditions (open house condition) in the metropolitan zone of Mexico City. At the same time radon monitoring was performed outdoors. The results show the general log-normal distribution of integrated indoor radon concentration with an annual indoor mean of 3.8 pCi·l−1. The seasonal variations show the minimum mean values in the summer season which are 39% lower than that in autumn. Equilibrium factors (F) were measured in 12 typical houses both in autumn and winter using a continuous working level monitor for short-lived radon decay products and H-chamber loaded with a short term electret (HST, E-PERM) for radon gas. The obtained total mean equilibrium factors are:F=0.41±0.17 andF=0.29±0.04 for indoor and outdoor, respectively. A quality program was also improved.

Determination of pollutants in dwellings by neutron activation analysis and X-ray fluorescence

Metallic pollutants were measured in dwellings in Mexico City by instrumental neutron activation analysis (INAA) and X-ray fluorescence techniques. Monitoring was performed in the west side of the city and in the winter season. In general the average concentration of contaminants collected, when compared with the average concentrations reported in a previous paper, have increased with time and in the particular case of lead and mercury some samples are above the indicative WHO maximum levels.

Metallic pollutants in Mexico Valley

Pollution has reached critical levels in the Metropolitan Zone of Mexico Valley. Concerned about, the Faculty of Chemistry has been performing environmental studies since 1995. This work presents the distribution and evolution of metallic pollutants in the Metropolitan zone of Mexico Valley. Samples consisted in aerosol filters (classified as total solid particles and respirable particles) as well as dry fallout. Samples were collected in several areas of the Mexico Valley, in different seasons along successive years. Metallic elements were determined by Instrumental Neutron Activation Analysis (INAA), X-ray fluorescence, and others techniques. Simultaneously, total solid particles (TSP) and respirable particles (RP) were determined by gravimetry. Elemental analysis of samples and matrix correlation allow us to establish some contaminant sources as well as relationship between concentration and relevant parameters.

INAA of Aerosol Samples in Mexico City

Total solid particles (TSP), respirable particles (RP) PM10 and 17 metallic pollutants were measured in dwellings in the Metropolitan Zone of Mexico Valley (MZMV) by gravimetry and instrumental neutron activation analysis (INAA). Monitoring was performed in Northeast, Center, Southeast and Southwest Zones in the winter and spring seasons. In general, the average concentration of contaminants (derived from industrial activities) that we have determined have increased with time. TSP and RP PM10 are often above the US and Mexican norms.