[show abstract][hide abstract] ABSTRACT: Exposure to lead in paint or lead residues in house dust and soil is one of the leading environmental risks to the health of children in the United States. Components of photochemical smog can increase the degradation of binders in lead paint, leading to increased release of lead pigment granules to hands in surface contact or for deposition in house dust and soil. This study uses photochemical air quality modeling to map areas susceptible to increased lead paint degradation as a result of photochemical atmospheric pollutants to prioritize areas of concern. Typical air quality episodes in the South Coast Air Basin of California (SoCAB) are modeled for the 1970s, 1980s, and 1990s. Results indicate that large areas of the SoCAB were susceptible to atmospheric-driven accelerated lead paint degradation. Inner city urban areas from central Los Angeles to Azusa and most of Orange County had the highest susceptibility to accelerated lead paint degradation, followed by inland locations near the San Bernardino Mountains. This study identifies photochemical oxidant gases as contributors to greater lead release from indoor painted surfaces in urban areas.
Environmental Science and Technology 12/2009; 43(23):8881-7. · 5.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: High ozone mixing ratios are a serious concern of public health. While ozone concentrations are high on weekdays due to anthropogenic emissions, they are often higher on weekends. This phenomenon has been named the weekend effect. This study uses the University of California, Irvine-California Institute of Technology (UCI-CIT) air quality model to assess the weekend effect in the South Coast Air Basin (SoCAB) of California. The weekend effect is reproduced by the model using an emissions inventory that includes representative weekday and weekend emissions. Additionally, this study modifies the Caltech Atmospheric Chemistry Mechanism (CACM), used in the UCI-CIT model, by introducing new heterogeneous reactions involving nitrogen oxides and chlorine. Eight modeling scenarios that include the nitrogen oxide renoxification and heterogeneous/multiphase chlorine reactions are presented to quantify how these reactions impact the weekend effect. The renoxification reaction and chlorine chemistry are found to increase ozone levels during weekdays and weekend days. However, increases in weekdays are generally larger than these increases that occur in the weekend. As a result, renoxification and chlorine chemistry lead to a net decrease in the average weekend effect intensity. The influence of renoxification on the weekend effect depends on the reaction probability (P), and the impact on the weekend effect is significant for P larger than 0.1. The influence of chlorine chemistry on the weekend effect depends strongly on the sea-salt source function that activates the chlorine chemistry. An amplification factor of 10 for the sea-salt source function, which produces the best agreement with observed chlorine levels in the SoCAB, leads to a basin-wide overall decrease of 29% in the weekend effect intensity with respect to the base case.