Carbonyls in the urban atmosphere of Monterrey, Mexico: sources, exposure, and health risk

Characteristics and sources of carbonyls in the ambient urban atmosphere of Monterrey, Mexico, were studied from April 10, 2012 to March 12, 2013. A total of 184 samples were collected using silica-gel cartridges impregnated with DNPH during morning (08:00-12:00 h) and afternoon (15:00-19:00 h) sampling periods. Samples were analyzed using high-performance liquid chromatography with an UV detector. Acetaldehyde was the most abundant carbonyl with mean concentrations of 13.08, 21.26, 12.19, and 11.78 mu g m(-3) for spring, summer, autumn, and winter, respectively. Corresponding seasonal concentrations of formaldehyde were 7.11, 10.42, 5.93, and 8.48 mu g m(-3). Both carbonyls showed a clear seasonal pattern and exhibited significantly higher levels in summer. Formaldehyde showed higher concentrations during the morning sampling period for all seasons except autumn, whereas acetaldehyde showed higher levels during the morning sampling period in summer and winter but higher concentrations during the afternoon sampling period in spring and autumn. Meteorological parameters and criteria air pollutants were measured and correlated with measured carbonyls using a principal component analysis. Prevailing winds showed that carbonyl levels were influenced by sources located to the SSE (during spring and summer), which include industrial, vehicular, and area sources. During autumn and winter, prevailing winds were from the NNE. Health risk assessment results show that values for the integrated lifetime cancer risk and non-cancer risk exceed acceptable risk levels and that long-term exposure to both carbonyls may result in a significant risk of cancer and adverse health effects.