25 research outputs found
Recommended from our members
Agricultural fires in the southeastern US during SEAC(4)RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol
Recommended from our members
Airborne measurements of western U.S. wildfire emissions: Comparison with prescribed burning and air quality implications
Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured from aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Biomass Burning Observation Project (BBOP), both in summer 2013. This study reports an extensive set of emission factors (EFs) for over 80 gases and 5 components of submicron particulate matter (PM1) from these temperate wildfires. These include rarely, or never before, measured oxygenated volatile organic compounds and multifunctional organic nitrates. The observed EFs are compared with previous measurements of temperate wildfires, boreal forest fires, and temperate prescribed fires. The wildfires emitted high amounts of PM1 (with organic aerosol (OA) dominating the mass) with an average EF that is more than 2 times the EFs for prescribed fires. The measured EFs were used to estimate the annual wildfire emissions of carbon monoxide, nitrogen oxides, total nonmethane organic compounds, and PM1 from 11 western U.S. states. The estimated gas emissions are generally comparable with the 2011 National Emissions Inventory (NEI). However, our PM1 emission estimate (1530 ± 570 Gg yr-1) is over 3 times that of the NEI PM2.5 estimate and is also higher thanthe PM2.5 emitted from all other sources in these states in the NEI. This study indicates that the source of OA from biomass burning in the western states is significantly underestimated. In addition, our results indicate that prescribed burning may be an effective method to reduce fine particle emissions
Chemically induced hair loss/alopecia
Increased shedding of hair and noticeable hair thinning or baldness (alopecia) are increasingly cited as side effects of exogenous chemicals/drugs. This chapter reviews some drugs implicated as well as mechanisms that may be responsible, describes criteria for defining the mechanism, and proposes animal and human assay models. This background provides the basis of similar judgment as relates to percutaneous penetration (and inhalation) of chemicals at the work site. Hair anatomy: Hair represents complete maturation of follicular matrical cells and is a fully cornified structure that emanates from a follicle and extends above the surface of the skin from varying distances. It has three components: an outer cuticle, a cortex, and an inner medulla. Hair grows in three phases: (1) growing or anagen, (2) involution or catagen, and (3) resting or telogen. Nonchemical-related hair loss: Few endogenous events affecting hair growth are delineated. Extreme starvation or protein deprivation may result in formation of sparse or brittle hair through diminished mitotic activity. Also major systemic insult, such as high fever, major surgery, illness, or trauma may result in hair follicles being thrown into an untimely telogen effluvium. Anagen versus telogen hair loss: Chemicals or medications may either cause excessive hair shedding by precipitating telogen development, directly poison the anagen root, or work in other undetermined ways. The phase of hair loss may be determined by examining the shed or easily plucked hair. Proving that alopecia in an individual is caused by a chemical/drug may be difficult; the most conclusive demonstration of chemical-/drug-related hair loss is reproduction of hair loss with repeated administration of the putative materials. However, the pathobiology of the response of the human hair follicle to chemotherapy is largely unknown. Hair loss is discussed in detail. Among the subjects of discussion are types of hair loss (e.g., anagen, medications precipitating telogen), chemicals causing hair loss (e.g., antimitotic agents, phenyl glycidyl ether), medications causing hair loss of unknown type (e.g., antithyroid drugs), medications possibly associated with hair loss, as well as chemically induced cosmetic alopecia, and typical scenarios in alleged occupational hair loss
Recommended from our members
Agricultural fires in the southeastern US during SEAC(4)RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol
Recommended from our members
Airborne measurements of western U.S. wildfire emissions: Comparison with prescribed burning and air quality implications
Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured from aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Biomass Burning Observation Project (BBOP), both in summer 2013. This study reports an extensive set of emission factors (EFs) for over 80 gases and 5 components of submicron particulate matter (PM1) from these temperate wildfires. These include rarely, or never before, measured oxygenated volatile organic compounds and multifunctional organic nitrates. The observed EFs are compared with previous measurements of temperate wildfires, boreal forest fires, and temperate prescribed fires. The wildfires emitted high amounts of PM1 (with organic aerosol (OA) dominating the mass) with an average EF that is more than 2 times the EFs for prescribed fires. The measured EFs were used to estimate the annual wildfire emissions of carbon monoxide, nitrogen oxides, total nonmethane organic compounds, and PM1 from 11 western U.S. states. The estimated gas emissions are generally comparable with the 2011 National Emissions Inventory (NEI). However, our PM1 emission estimate (1530 ± 570 Gg yr-1) is over 3 times that of the NEI PM2.5 estimate and is also higher thanthe PM2.5 emitted from all other sources in these states in the NEI. This study indicates that the source of OA from biomass burning in the western states is significantly underestimated. In addition, our results indicate that prescribed burning may be an effective method to reduce fine particle emissions