Real-Time Prediction of Size-Resolved Ultrafine Particulate Matter on Freeways

Ultrafine particulate matter (UFP; diameter <0.1 μm) concentrations are relatively high on the freeway, and time spent on freeways can contribute a significant fraction of total daily UFP exposure. We model real-time size-resolved UFP concentrations in summer time on-freeway air. Particle concentrations (32 bins, 5.5 to 600 nm) were measured on Minnesota freeways during summer 2006 and 2007 (Johnson, J. P.; Kittelson, D. B.; Watts, W. F. Environ. Sci. Technol. 2009, 43, 5358−5364). Here, we develop and apply two-way stratified multilinear regressions, using an approach analogous to mobile-monitoring land-use regression but using real-time meteorological and traffic data. Our models offer the strongest predictions in the 10–100 nm size range (adj-<i>R</i>²: 0.79–0.89, average adj-<i>R</i>²: 0.85) and acceptable but weaker predictions in the 130–200 nm range (adj-<i>R</i>²: 0.41–0.62, average adj-<i>R</i>²: 0.52). The aggregate model for total particle counts performs well (adj-<i>R</i>² = 0.77). Bootstrap resampling (<i>n</i> = 1000) indicates that the proposed models are robust to minor perturbations in input data. The proposed models are based on readily available real-time information (traffic and meteorological parameters) and can thus be exploited to offer spatiotemporally resolved prediction of UFPs on freeways within similar geographic and meteorological environments. The approach developed here provides an important step toward modeling population exposure to UFP

Rural Alaska Water Treatment and Distribution Systems Incur High Energy Costs: Identifying Energy Drivers Using Panel Data Analysis for 78 Communities

The energy consumption for water treatment and distribution in rural Alaska communities that represent one of the coldest and most isolated regions in the US has been unexplored. Using energy audits data from Alaska Native Tribal Health Consortium (ANTHC), we investigate the annual energy consumption patterns for water treatment and distribution in 78 rural Alaska communities (average population < 500 people) along with seasonal, regional, and population impacts, and water treatment/distribution system types. Regional trends of per capita annual energy consumption are as follows: Interior > Northern > Southwest > Gulf coast > Southeast regions of Alaska. Our results indicate that the per capita energy consumption is highest during the winter and lowest during the summer. Generally, the per capita energy consumption decreases with an increasing population. The variation of per capita energy consumption based on water distribution types shows that piped circulating systems consume the most energy, followed by washeteria, piped pressure, and closed haul. At the water treatment plant, space heating and electrical motors have the highest per capita energy consumption, followed by domestic hot water, tank heating, and lighting. The findings in this work suggest that per capita energy consumption (kWh/p) for water treatment and distribution in rural Alaska is about 12–26 times higher than the national average and about two orders of magnitude higher economic costs for the same. Overall, this work sheds light on energy use for water treatment and distribution in rural Alaska and establishes a baseline that would be useful for the rural Alaska communities’ adaptation to climate change efforts, specifically in planning for and designing new water systems or updating existing systems