نتایج جستجو برای: air ozone concentration enrichment face
تعداد نتایج: 782316 فیلتر نتایج به سال:
BACKGROUND Fraction of exhaled nitric oxide (FENO) is a promising non-invasive index of airway inflammation that may be used to assess respiratory effects of air pollution. We evaluated FENO as a measure of airway inflammation after controlled exposure to diesel exhaust or ozone. METHODS Healthy volunteers were exposed to either diesel exhaust (particle concentration 300 μg/m3) and filtered a...
Ground-level ozone concentration is a key indicator of air quality. There may exist sudden changes in ozone concentration data over a long time horizon, which may be caused by the implementation of government regulations and policies, such as establishing exhaust emission limits for on-road vehicles. To monitor and assess the efficacy of these policies, we propose a methodology for detecting ch...
In this study the variations in the surface ozone concentration, the solar ultraviolet radiation and the meteorological parameters at the ground before, during and after the total solar eclipse of 29 March 2006 have been examined. This analysis is based on the measurements performed at four stations located in the greater Athens basin in Greece. The experimental data demonstrated that the solar...
The ground-level ozone is a pervasive air pollutant, which can be potentially elevated by flaring emissions during chemical plant turnaround operations (i.e., startup and shutdown). Especially in chemical plant concentrated regions, the regional air-quality (i.e., the ozone concentration) may be aggravated by simultaneous turnaround emissions from multiple chemical plants. Thus, under viable ma...
The Citrus genus includes a large number of species and varieties widely cultivated in the Central Valley of California and in many other countries having similar Mediterranean climates. In the summer, orchards in California experience high levels of tropospheric ozone, formed by reactions of volatile organic compounds (VOC) with oxides of nitrogen (NOx). Citrus trees may improve air quality in...
Fungal spores are known to cause allergic sensitization. Recent studies reported a strong association between asthma symptoms and thunderstorms that could be explained by an increase in airborne fungal spore concentrations. Just before and during thunderstorms the values of meteorological parameters rapidly change. Therefore, the goal of this study was to create a predictive model for hourly co...
BACKGROUND Elevated tropospheric ozone severely affects not only yield but also the morphology, structure and physiological functions of plants. Because of concerns regarding the potential environmental risk of transgenic crops, it is important to monitor changes in transgenic insect-resistant rice under the projected high tropospheric ozone before its commercial release. METHODOLOGY/PRINCIPA...
a two-week tunnel study was conducted in monterrey, mexico during june 2009 to characterizevolatile organic compound (voc) emissions from the local vehicle fleet and estimate the correspondingemission factors (efs). the loma larga tunnel (llt), a 532 meter-long structure that is mainly used by lightduty gasoline-powered vehicles was used as the experimental set-up. ambient air samples (2-hour a...
BACKGROUND Little is known about the effect of exposure to air pollution during exercise or time spent outdoors on the development of asthma. We investigated the relation between newly-diagnosed asthma and team sports in a cohort of children exposed to different concentrations and mixtures of air pollutants. METHODS 3535 children with no history of asthma were recruited from schools in 12 com...
Methane (CH(4)) contributes to the growing global background concentration of tropospheric ozone (O(3)), an air pollutant associated with premature mortality. Methane and ozone are also important greenhouse gases. Reducing methane emissions therefore decreases surface ozone everywhere while slowing climate warming, but although methane mitigation has been considered to address climate change, i...
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