نتایج جستجو برای: level ozone
تعداد نتایج: 1099220 فیلتر نتایج به سال:
Background ozone, known as the ozone that occurs in the troposphere as a result of biogenic emissions without photochemical influences, has a close relationship with human health risk. The prediction of the background ozone level by an air quality model could cover a wider region, whereas a measurement method can only record at monitoring sites. The problem is that simulation with deterministic...
BACKGROUND Substantial epidemiological studies demonstrate associations between exposure to ambient ozone and mortality. A few studies simply examine the modification of this ozone effect by individual characteristics and socioeconomic status, but socioeconomic status was usually coded at the city level. METHODS This study used a case-crossover design to examine whether impacts of ozone on mo...
This paper analyses daily ozone, cloud cover, solar radiation and broadband UV-B data for winter/spring at a low pollution Southern Hemispheric sub-tropical site (27.80 degrees S). The average ozone concentration for the period was 290 DU. An anti-correlation is presented between the ozone and UV-B data over a 5 day period during winter. An ozone deficiency of 45 DU was calculated for the cloud...
In many areas, natural sources contribute a substantial fraction of volatile organic compound (VOC) emissions, which are precursors to tropospheric ozone (O3). To investigate the significance of biogenic VOC emissions on ozone formation, meteorological and air quality modelling were used to generate hourly ozone estimates for a case-study high ozone episode in the Mid-Atlantic region of the Uni...
Measurements of the total burden and of the concentration versus altitude profiles of ozone have been made with a ground-based heterodyne radiometer at Pasadena, California. The measurements were made in the 9.5-micrometer wavelength region, where a strong ozone infrared absorption band exists. The radiometer measured solar absorption at selected wavelengths, with a spectral resolution of 0.001...
Ozone injury to natural vegetation is being increasingly surveyed throughout the northern hemisphere. There exists a growing list of species showing visible 'ozone-like' symptoms which needs to be validated. This study presents the results from a test survey of ozone injury to forest vegetation in the light exposed sites of five Swiss level II plots, for the new ICP-Forests protocol. With AOT40...
In order to reduce the level of dithiocarbamate fungicide mancozeb residues in blackcurrants, two different ozone treatment procedures were evaluated. The first one entailed washing the plant material with an aqueous solution of ozone. This ozone enriched water solution allowed for a 59% reduction of mancozeb residues, compared with the initial concentration. The latter method was based on the ...
2687 Since the passage of the original Clean Air Act in 1963, US state and federal governments have implemented numerous policies designed to reduce human exposure to ground-level ozone pollution. Ozone is an odorless, colorless gas that has been linked to asthma, increased susceptibility to pneumonia and bronchitis, and damage to crops and natural vegetation. Michelle L. Bell et al. (2004) hav...
Abstract: Ozone concentration has a complex distribution in mountain areas, but the low spatial density of high elevation monitoring stations has limited our understanding of ozone behavior. To achieve high spatial density, mobile measurement was carried out using a portable ozone monitor based on a semiconductor sensor. On the elevation gradient of a relatively low hill (273 m above seal level...
In order to explore the temporal-spatial patterns and possible health effects of ozone in Shenzhen, daily concentrations of ozone and the daily mortality caused by cardiovascular and respiratory diseases were collected. Using Geographic Information System (GIS) and SPSS, the spatial and temporal patterns of ozone in Shenzhen were illustrated. Using a generalized additive model (GAM), the associ...
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