Time-Location Patterns of a Population Living in an Air Pollution Hotspot

This study characterized the time-location pattern of 107 residents living in air pollution hotspots, the Waterfront South and Copewood/Davis Streets communities in Camden, NJ. Most residents in the two communities are minority and impoverished individuals. Results showed that employment status played the fundamental role in determining time-location patterns of this study population, and the variations of time-location pattern by season and by day-type were partially attributed to employment status. Compared to the National Human Activity Pattern Survey, the Camden cohort spent significantly more time outdoors (3.8 hours versus 1.8 hours) and less time indoors (19.4 hours versus 20.9 hours) than the general US population, indicating a higher risk of exposure to ambient air pollution for the Camden cohort. The findings of the study are important for understanding exposure routes and sources for the socioeconomically disadvantaged subgroup and ultimately help develop effective strategies to reduce community exposure to ambient air pollution in “hotspots”

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Interconversion of Chromium Species During Air Sampling: Effects of O₃, NO₂, SO₂, Particle Matrices, Temperature, and Humidity

The interconversion between Cr­(VI), a pulmonary carcinogen, and Cr­(III), an essential human nutrient, poses challenges to the measurement of Cr­(VI) in airborne particles. Chamber and field tests were conducted to identify the factors affecting Cr­(VI)–Cr­(III) interconversion in the basic filter medium under typical sampling conditions. In the chamber tests, isotopically enriched ⁵³Cr­(VI) and ⁵⁰Cr­(III) were spiked on diesel particulate matter (DPM) and secondary organic aerosol (SOA) that were precollected on a basic MCE filter. The filter samples were then exposed to clean air or the air containing SO₂ (50 and 160 ppb), 100 ppb O₃, or 150 ppb NO₂ for 24 h at 16.7 LPM flow rate at designated temperature (20 and 31 °C) and RH (40% and 70%) conditions. Exposure to 160 ppb SO₂ had the greatest effect on ⁵³Cr­(VI) reduction, with ⁵³Cr­(VI) recovery of 31.7 ± 15.8% (DPM) and 42.0 ± 7.9% (SOA). DPM and SOA matrix induced ⁵³Cr­(VI) reduction when exposed to clean air while reactive oxygen species in SOA could promote ⁵⁰Cr­(III) oxidation. Deliquescence when RH increased from 40% to 70% led to conversion of Cr­(III) in SOA, whereas oxidized organics in DPM and SOA enhanced hygroscopicity and thus facilitated Cr­(VI) reduction. Field tests showed seasonal variation of Cr­(VI)–Cr­(III) interconversion during sampling. Correction of the interconversion using USEPA method 6800 is recommended to improve accuracy of ambient Cr­(VI) measurements