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1.
Forced expiratory volume in 1 second (FEV1) was measured in 21 men exercising while exposed to four O3 concentrations (0.0, 0.08, 0.10, and 0.12 ppm). A lognormal multiple linear regression model was fitted to their mean FEV1 measurements to predict FEV1 percent decrease as a function of O3 concentration and exposure duration. The exercise level used was probably comparable to heavy manual labor. The longest O3 exposure studied was 6 h. Extrapolating cautiously to an 8-h workday of heavy manual labor, the model predicts that O3 concentrations of 0.08, 0.10, and 0.12 ppm would decrease FEV1 by 9, 15, and 20 percent, respectively. 相似文献
2.
A plant injury mathematical model, applied previously to acute and chronic leaf injury data, is used here to model National Crop Loss Assessment Network (NCLAN) data for 15 cultivars and to calculate species parameters from the cultivar analyses. Percent crop yield reduction is estimated as a function of a new parameter, the effective mean O 3 concentration: m e = [(Σ c h ?1/v)/n] ?v, where c h is the hourly average ambient O 3 concentration for each daytime hour (defined here as 9:00 A.M.–4:00 P.M., always standard time) of data available at an air sampling site for summer (defined here as June 1–August 31), n is the total number of such available hours, and v is an exposure time-concentration parameter, calculated here to be approximately –0.376. Crop yield reduction for soybean is calculated here as z = 0.478 In ( tm e 2-66) – 0.42, where z is the Gaussian transform of percent crop reduction, t is the hours of exposure (525 h is used here; 7 h/day for 75 days), and In indicates that the natural logarithm is taken of the quantity within parentheses. Crop yield reductions for seven plant species are estimated with similar equations for each of the 1824 site-years of 1981–1983 hourly O 3 concentration data available in the National Aerometric Data Bank (NADB). County-average effective mean O 3 concentrations are indicated by shading on a U.S. map. State-average O 3 parameters and estimated percent crop yield reductions are tabulated. The National Ambient Air Quality Standard (NAAQS) for O 3 specifies that, on the average, the second highest daily maximum 1-h average O 3 concentration in a year shall not exceed 0.12 ppm. For years 1981-1983,71% of the NADB sites recorded annual second highest daily maximum 1-h average O3 concentrations below 0.125 ppm (for summer daytime hours). Ambient O 3 concentrations reduced the total U.S. crop yield an estimated 5% for years 1981–1983. (Summer, daytime, and all acronyms are always used herein as defined above.) 相似文献
3.
Leaf injury data from acute and chronic exposure studies of Dare soybean were regressed against the logarithms of exposure time and O 3 and SO 2 concentrations to develop a new two-pollutant leaf injury model (which explains 88% of the variance) and to calculate the parameters of best fit for this new model and a previously developed one-pollutant model. Using the calculated parameters, the percentage of leaf surface Injured over a growing season by O 3, SO 2, or both simultaneously was estimated for an ambient air sampling site located 2 miles from a coal burning power plant. For this site, the one- and two-pollutant models predicted that SO 2 effects would be negligible If SO 2 concentrations never exceeded the National Ambient Air Quality Standard (NAAQS) of 0.50 ppm, averaged over 3 h. However, calculations suggest that O 3 may injure up to 24% of Dare soybean leaf surface over a growing season even though the O 3 NAAQS of 0.12 ppm, averaged over 1 h, is never exceeded. Because the 3 h SO 2 standard is exceeded at very few places, the O 3 model is usually sufficient to estimate Dare soybean leaf Injury. Leaf injury is estimated by taking the logarithm of the summation of each daytime hour’s exponentiated O 3 concentration (c) measured at an ambient air sampling site over a growing season. This is expressed as: z = -0.0828 + 0.4876 in (Σ co 3 2.618), where z is the Gaussian transform of percent leaf injury. The methods developed in this paper, using Dare soybean data as an example, may apply to other plants. 相似文献
4.
Ambient O 3 exposures have reduced growth rates of tree genotypes in some areas of the United States. For characterizing O 3 exposures in forested areas, data from primarily population-oriented sites have been used. It has been speculated that exposures calculated from population-oriented sites provide estimates greater than those that would actually be experienced in the majority of forested areas. Accordingly, we compared 1988 O 3 data from three remote forested sites with data from several population-oriented monitoring sites in and around the mid? and southern Appalachian Mountains. The number of hours ≥0.08 ppm was lower at the remote forested sites than at the nearby population-oriented locations. In addition, we characterized the temporal variability of O 3 exposures in forested regions of the United States and Canada for the period 1978-1988. We found that the years of highest O 3 exposure in the eastern United States during 1978-1988 were 1978, 1980, 1983, and 1988, with 1988 being the worst year in four of seven eastern forest regions. In 1988, the Whiteface Mountain summit site (1483 m) experienced approximately 10 percent more hourly average concentrations ≥0.08 ppm than in the second highest O 3 exposure year (i.e., 1979). Consistently throughout the 11-year period, the highest O 3 exposures at the Whiteface Mountain site occurred during the late evening and early morning hours, with the result that the longterm 7-h (0900-1559h) exposure index could not distinguish those years in which the highest exposures occurred from those in which the lowest occurred. Similar to the Whiteface Mountain site, two high-elevation Shenandoah National Park sites experienced their highest O 3 exposures in 1988. With the exception of 1986, the lower elevation site (Dickey Ridge) consistently experienced more frequent occurrences of hourly average concentrations ≥0.08 ppm than the higher elevation site (Big Meadows). 相似文献
5.
Soybean percent crop reduction was estimated as a function of ambient O 3 concentrations for each of 80 agricultural sites in the National Aerometric Data Bank (NADB) for each available year of data for years 1981-1985. Fourteen O 3 concentration statistics were calculated for each of the resulting 320 site-years of data. The two statistics that correlated best with estimated crop reduction were an effective mean O 3 concentration (1 percent of variance unexplained) and an arithmetic mean O 3 concentration (4 percent unexplained). The worst correlation of the 14 was for the statistic used in the present O 3 National Ambient Air Quality Standard (NAAQS), the second highest daily maximum 1-h O 3 concentration (42 percent unexplained). The number of site-years for estimated percent soybean yield reductions was plotted versus increasing O 3 concentrations for each of the 14 O 3 statistics. A maximum crop reduction line was drawn on each plot. These lines were used to estimate (and list) potential ambient O 3 standards for each of the 14 statistics that would limit soybean crop reduction at agricultural. NADB sites to 5, 10, 15, or 20 percent. 相似文献
6.
To test for an increased reaction to ozone (O 3) in older individuals following an initial exposure, and to test for adaptation and its duration, we exposed 10 men and 6 women (60-89 years old) in an environmental chamber to filtered air and 3 consecutive days of O 3 exposure (0.45 ppm), followed by a fourth O 3 exposure day after a two day hiatus. Subjects alternated 20-min exercise (minute ventilation = 27 L) and rest periods for 2 hours during each exposure. Subjects rated from one to five, 16 possible respiratory/exercise symptoms prior to and following the exposure. Pulmonary function tests were performed before, and during each rest period and following the exposure. Metabolic measurements were obtained during each exercise period. No significant changes in any symptom question occurred, in spite of a threefold increase in the total number of reported symptoms during O 3 exposure. Small but significant pre-to-post decrements on the first and second O 3 days in forced vital capacity (FVC—111 and 104 mL), forced expiratory volume in 1 (FEV 1—171 and 164 mL) and 3 seconds (FEV 3—185 and 172 mL) occurred without concomitant changes in any flow parameter of the forced expiratory maneuver. No differences in the group mean response in FVC, FEV 1, OR FEV 3 on the third or fourth day of O 3 exposure and the filtered air exposure were found. The observed changes were due to significant physiological changes in eight of the subjects. Unlike young subjects, no evidence of an increased pulmonary function response to a second consecutive O 3 exposure was observed. Changes in small airway response to O 3 (below 75 percent of FVC) without irritant receptor activation, would explain the observed pattern of response. 相似文献
7.
The aim of this study was to assess the acute health effects of individual ozone (O3) exposure on the respiratory system in the elderly. A total of 40 non-smoking elderly volunteers completed personal 24 h of measurement for O3 and fine particulate matter (PM2.5). To assess health effects, we measured the pulmonary function and five inflammatory biomarkers in exhaled breath condensate (EBC), including interleukin-2 (IL-2), interferon-γ (IFN-γ), prostaglandin E2 (PGE2), and tumor necrosis factor α/β (TNFα/β). We used the generalized additive model to analyze the association between O3 and these health effects, after adjusting PM2.5, BMI, and sex as confounders. As a result, we found a negative correlation between O3 and forced vital capacity (FVC) or forced expiratory volume-one second (FEV1). With the increasing of O3 by 10 μg/m3, FVC and FEV1 decreased by 0.13 L (95% CI 0.01, 0.26) and 0.11 L (95% CI 0.02, 0.20), respectively. We found no statistical significance between O3 and biomarkers in EBC. The results suggested that individual 24-h O3 exposure was associated with decreased pulmonary function in the elderly. 相似文献
8.
Non-methane organic carbon (NMOC) measurements made in Atlanta, Georgia from 1999–2007 are used with nitrogen oxide (NO x or NO y) and ozone (O 3) data to investigate relationships between O 3 precursors and peak 8-hour O 3 concentrations in the city. Data from a WNW-to-ENE transect of sites illustrate that the mean urban peak 8-hour O 3 excess constitutes about 20% of the peak 8-hour O 3 measured at the area-wide maximum O 3 site when air-mass movement is from the northwest quadrant; local influence is potentially greater on days with more stagnation or recirculation. The peak 8-hour O 3 concentrations in Atlanta increase as (1) surface temperature (T), ambient NMOC and NO y concentrations, and previous-day peak O 3 concentrations increase, and as (2) relative humidity, surface wind speeds, and ratios of NMOC-to-NO y decrease. An observation-based statistical model is introduced to relate area-wide peak 8-hour O 3 concentrations to ambient NMOC and NO y concentrations, while accounting for the non-linear dependences of peak 8-hour O 3 concentrations on meteorological factors. On the majority of days when the area-wide peak 8-hour O 3 exceeds 75 ppbv, meteorologically-adjusted peak 8-hour O 3 concentrations increase as ambient NMOC concentrations increase (NMOC sensitive) and ambient NO y concentrations decrease. This result contrasts with regional conditions in which O 3 formation appears to be NO x-sensitive in character. The results offer observationally-based information of relevance to O 3 management strategies in the Atlanta area, potentially contributing to “weight-of-evidence” assessments. 相似文献
9.
The main use of air quality forecast (AQF) models is to predict ozone (O 3) exceedances of the primary O 3 standard for informing the public of potential health concerns. This study presents the first evaluation of the performance of the Eta-CMAQ air quality forecast model to predict a variety of widely used seasonal mean and cumulative O 3 exposure indices associated with vegetation using the U.S. AIRNow O 3 observations. These exposure indices include two concentration-based O 3 indices, M7 and M12 (the seasonal means of daytime 7-h and 12-h O 3 concentrations, respectively), and three cumulative exposure-based indices, SUM06 (the sum of all hourly O 3 concentrations ≥ 0.06 ppm), W126 (hourly concentrations weighed by a sigmoidal weighting function), and AOT40 (O 3 concentrations accumulated over a threshold of 40 ppb during daylight hours). During a three-month simulation (July–September 2005), the model over predicted the M7 and M12 values by 8–9 ppb, or a NMB value of 19% and a NME value of 21%. The model predicts a central belt of high O 3 extending from Southern California to Middle Atlantic where the seasonal means, M7 and M12 (the seasonal means of daytime 7-h and 12-h O 3 concentrations), are higher than 50 ppbv. In contrast, the model is less capable of reproducing the observed cumulative indices. For AOT40, SUM06 and W126, the NMB and NME values are two- to three-fold of that for M7, M12 or peak 8-h O 3 concentrations. The AOT40 values range from 2 to 33 ppm h by the model and from 1 to 40 ppm h by the monitors. There is a significantly higher AOT40 value experienced in the United States in comparison to Europe. The domain-wide mean SUM06 value is 14.4 ppm h, which is about 30% higher than W126, and 40% higher than AOT40 calculated from the same 3-month hourly O 3 data. This suggests that SUM06 and W126 represent a more stringent standard than AOT40 if either the SUM06 or the W126 was used as a secondary O 3 standard. Although CMAQ considerably over predicts SUM06 and W126 values at the low end, the model under predicts the extreme high exposure values (>50 ppm h). Most of these extreme high values are found at inland California sites. Based on our analysis, further improvement of the model is needed to better capture cumulative exposure indices. 相似文献
10.
We measured toxic air pollutants along Oba Akran road in Lagos to evaluate pedestrian exposure. PM 10, CO, O 3, NO 2, SO 2, CH 4, noise, wind velocity and temperature were measured simultaneously with portable analyzers. Our results showed that pedestrian exposure to PM 10 (with an average of 274.6 μg m −3 for all samples) and CO (with an average of 19.27 ppm for all samples) was relatively high. CO is a traffic-related pollutant, so the influence of the local traffic emissions on CO levels is strong. The high concentration of the PM 10 measured at the three environments also suggests that the traffic is a major source of ultrafine particles. The overall average concentrations for the 72-day experimental period for SO 2, NO 2 and O 3 are 101.2, 62.5 and 0.32 ppb respectively, all of which are below the US national ambient air quality standards. Strong traffic impacts can be observed from the concentrations of some of these pollutants measured in these three environments. Most clear is a reflection of diesel truck traffic activity rich in black carbon concentrations. The diurnal variation of O 3 and NO 2 also showed that NO 2 was depleted by photochemically formed O 3 during the day and replenished at night as O 3 was destroyed. A multivariate statistical analysis (Principal Component Analysis, Factor Analysis) has been applied to a set of data in order to determine the contribution of different sources. It was found that the main principal components, extracted from the air pollution data, were related to gasoline combustion, oil combustion and ozone interactions. 相似文献
11.
Abstract This study tested the hypothesis that exposure to mixtures containing fine particles and ozone (O 3) would cause pulmonary injury and decrements in functions of immunological cells in exposed rats (22–24 months old) in a dose-dependent manner. Rats were exposed to high and low concentrations of ammonium bisulfate and elemental carbon and to 0.2 ppm O 3. Control groups were exposed to purified air or O 3 alone. The biological end points measured included histopathological markers of lung injury, bronchoalveolar lung fluid proteins, and measures of the function of the lung’s innate immuno-logical defenses (macrophage antigen-directed phagocytosis and respiratory burst activity). Exposure to O 3 alone at 0.2 ppm did not result in significant changes in any of the measured end points. Exposures to the particle mixtures plus O 3 produced statistically significant changes consistent with adverse effects. The low-concentration mixture produced effects that were statistically significant compared to purified air but, with the exception of macrophage Fc receptor binding, exposure to the high-concentration mixture did not. The effects of the low- and high-concentration mixtures were not significantly different. The study supports previous work that indicated that particle + O 3 mixtures were more toxic than O 3 alone. 相似文献
12.
Caribbean pine, an economically important tree of tropical lowlands, is at risk of SO 2 exposure in certain locales. Twenty-week old seedlings of Caribbean, Scots, and Virginia pine were exposed to 0.5, 1.0, and 2.0 ppm SO 2 (1300, 2600, and 5200 μm ?3, respectively) for 1, 2, 4, and 8 h in modified controlled-environment chambers. Severity of SO 2-induced leaf necrosis for each species was related to SO 2 concentration and exposure duration using a regression model. The three dose-response relationships differed in detail, but Caribbean pine seedlings were generally as sensitive to SO 2 as seedlings of the two highly sensitive temperate species. In addition, 173 4-wk-old Caribbean pine seedlings were exposed to 0.5 ppm SO 2 for 4 h. Over one-half of these seedlings exhibited some necrosis and over one-sixth had more than 5 percent of leaf surface necrotic. It is concluded that Caribbean pine seedlings are highly sensitive to acute doses of SO 2. 相似文献
13.
Abstract An ozone (O 3) exposure assessment study was conducted in Toronto, Ontario, Canada during the winter and summer of 1992. A new passive O 3 sampler developed by Harvard was used to measure indoor, outdoor, and personal O 3 concentrations. Measurements were taken weekly and daily during the winter and summer, respectively. Indoor samples were collected at a total of 50 homes and workplaces of study participants. Outdoor O 3 concentrations were measured both at home sites using the passive sampler and at 20 ambient monitoring sites with continuous monitors. Personal O 3 measurements were collected from 123 participants, who also completed detailed time-activity diaries. A total of 2,274 O 3 samples were collected. In addition, weekly air exchange rates of homes were measured. This study demonstrates the performance of our O 3 sampler for exposure assessment. The data obtained are further used to examine the relationships between personal, indoor (home and workplace), and outdoor O 3 concentrations, and to investigate outdoor and indoor spatial variations in O 3 concentrations. Based on home outdoor and indoor, workplace, and ambient O 3 concentrations measured at the Ontario Ministry of the Environment (MOE) sites, the traditional microenvironmental model predicts 72% of the variability in measured personal exposures. An alternative personal O 3 exposure model based on outdoor measurements and time-activity information is able to predict the mean personal exposures in a large population, with the highest R 2 value of 0.41. 相似文献
14.
Eight years of ambient monitoring data (1978-1985) were used to characterize O 3 concentrations in eight forested areas of the United States. The analysis focused on the annual number of occurrences of hourly averaged O 3 concentrations ≥0.07, 0.08, and 0.10 ppm during the growing season (April-October) as well as during the early (April-June) and late (July-October) portions of the growing season. On the average, within those areas studied, elevated O 3 concentrations occurred more often in the Piedmont/Mountain/Ridge-Valley and Ohio River Valley areas than elsewhere. In the eastern United States, 1978, 1980, and 1983 were generally the years with the most occurrences of elevated O 3 concentrations. In these years, the later part (July-October) of the growing season experienced more elevated concentrations than the earlier part. The results presented in this analysis were used to develop recommendations for future O 3 effects research with respect to forested areas and related exposure regimes. 相似文献
16.
Cutleaf coneflower ( Rudbeckia laciniata L.) seedlings were placed into open-top chambers in May, 2004 and fumigated for 12 wks. Nine chambers were fumigated with either carbon-filtered air (CF), non-filtered air (NF) or twice-ambient (2×) ozone (O 3). Ethylenediurea (EDU) was applied as a foliar spray weekly at 0 (control), 200, 400 or 600 ppm. Foliar injury occurred at ambient (30%) and elevated O 3 (100%). Elevated O 3 resulted in significant decreases in biomass and nutritive quality. Ethylenediurea reduced percent of leaves injured, but decreased root and total biomass. Foliar concentrations of cell-wall constituents were not affected by EDU alone; however, EDU × O 3 interactions were observed for total cell-wall constituents and lignocellulose fraction. Our results demonstrated that O 3 altered the physiology and productivity of cutleaf coneflower, and although reducing visible injury EDU may be phytotoxic at higher concentrations. 相似文献
17.
The effect of HO x radicals (OH and HO 2) and ozone (O 3) on aerosol formation and aging has been studied. Experiments were performed in presence as well as in absence of oxygen in a flow-through chamber at 299 K for three organic precursor gases, isoprene, α-pinene and m-xylene. The HO x source was the UV photolysis of humidified air or nitrogen and was measured with a GTHOS (Ground-based Tropospheric Hydrogen Oxides Sensor). The precursor gases concentration was monitored with an online GC-FID. The aerosol mass was then quantified by a Tapered Element Oscillating Microbalance (TEOM). Typical oxidant mixing ratios were (0–4.5) ppm for O 3, 200 pptv for OH and 3 ppbv for HO 2. A simple kinetics model is used to infer the aerosol production mechanism. In the present of O 3 (or O 2), the SOA yields were 0.46, 0.036 and 0.12 for α-pinene with an initial concentration of 100 ppbv (RH = 37%), isoprene with an initial concentration of 177 ppbv (RH = 50%) and m-xylene with an initial concentration of 100 ppbv (RH = 37%), respectively. When the chosen precursor gases reacted with HO x in the absence of O 3, the maximum SOA yields were significantly increased by factors of 1.6 for isoprene 1.1 for α-pinene, and 3 for m-xylene respectively. The comparison of the calculated and measured potential aerosol mass concentrations as function of time shows that presence of ozone or oxygen can influence the aerosol yield and the absence of ozone or oxygen in the system resulted in high concentrations of its organic aerosol products. 相似文献
18.
The removal of SO 2 with atomization of a slaked lime slurry and supplemental injection of gaseous NH 3 were tested in a conventional spray dryer/baghouse system for SO 2 concentrations of 2000 ppm and 3000 ppm and a 30° F approach to saturation. Results at 3000 ppm of SO 2 showed an average SO 2 removal efficiency of 90.3 percent at a combined stoichiometric ratio of 0.95-1.10 and an average overall sorbent utilization of 91.6 percent. The overall molal ratio of NH 3/SO 2 reaction was found to be 2:1 under the test conditions Particle size analyses, and EP toxicity tests were conducted on the products of the reactions. 相似文献
19.
ABSTRACT While researchers have linked acute (less than 12-hr) ambient O 3, PM 25, and CO concentrations to a variety of adverse health effects, few studies have characterized short-term exposures to these air pollutants, in part due to the lack of sensitive, accurate, and precise sampling technologies. In this paper, we present results from the laboratory and field evaluation of several new (or modified) samplers used in the “roll-around” system (RAS), which was developed to measure 1-hr O 3, PM 25, and CO exposures simultaneously. All the field evaluation data were collected during two sampling seasons: the summer of 1998 and the winter of 1999. To measure 1-hr O 3 exposures, a new active O 3 sampler was developed that uses two nitrite-coated filters to measure O 3 concentrations. Laboratory chamber tests found that the active O 3 sampler performed extremely well, with a collection efficiency of 0.96 that did not vary with temperature or relative humidity (RH). In field collocation comparisons with a reference UV photometric monitor, the active O 3 sampler had an effective collection efficiency ranging between 0.92 and 0.96 and a precision for 1-hr measurements ranging between 4 and 6 parts per billion (ppb). The limits of detection (LOD) of this method were 9 ppb-hr for the chamber tests and ~16 ppb-hr for the field comparison tests. PM 2.5 and CO concentrations were measured using modified continuous monitors—the DustTrak and the Langan, respectively. A size-selective inlet and a Nafion dryer were placed upstream of the DustTrak inlet to remove particles with aerodynamic diameters greater than 2.5 um and to dry particles prior to the measurements, respectively. During the field validation tests, the DustTrak consistently reported higher PM 2.5 concentrations than those obtained by the collocated 12-hr PM 2 5 PEM samples, by approximately a factor of 2. After the DustTrak response was corrected (correction factor of 2.07 in the summer and 2.02 in the winter), measurements obtained using these methods agreed well with R 2 values of 0.87 in the summer and 0.81 in the winter. The results showed that the DustTrak can be used along with integrated measurements to measure the temporal and spatial variation in PM 2 5 exposures. Finally, during the field validation tests, CO concentrations measured using the Langan were strongly correlated with those obtained using the reference method when the CO levels were above the LOD of the instrument [~1 part per million (ppm)]. 相似文献
20.
The effects of elevated concentrations of atmospheric tropospheric ozone (O 3) on DNA damage in five trembling aspen ( Populus tremuloides Michx.) clones growing in a free-air enrichment experiment in the presence and absence of elevated concentrations of carbon dioxide (CO 2) were examined. Growing season mean hourly O 3 concentrations were 36.3 and 47.3 ppb for ambient and elevated O 3 plots, respectively. The 4th highest daily maximum 8-h ambient and elevated O 3 concentrations were 79 and 89 ppb, respectively. Elevated CO 2 averaged 524 ppm (+150 ppm) over the growing season. Exposure to O 3 and CO 2 in combination with O 3 increased DNA damage levels above background as measured by the comet assay. Ozone-tolerant clones 271 and 8L showed the highest levels of DNA damage under elevated O 3 compared with ambient air; whereas less tolerant clone 216 and sensitive clones 42E and 259 had comparably lower levels of DNA damage with no significant differences between elevated O 3 and ambient air. Clone 8L was demonstrated to have the highest level of excision DNA repair. In addition, clone 271 had the highest level of oxidative damage as measured by lipid peroxidation. The results suggest that variation in cellular responses to DNA damage between aspen clones may contribute to O 3 tolerance or sensitivity. 相似文献
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