An Air Quality Data Analysis System for Interrelating Effects,Standards, and Needed Source Reductions: Part 11. A Lognormal Model Relating Human Lung Function Decrease to O3 Exposure

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.     

Spatial and Temporal Variability of Ozone Exposure in Forested Areas of the United States and Canada: 1978—1988

Ambient O₃ exposures have reduced growth rates of tree genotypes in some areas of the United States. For characterizing O₃ 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 O₃ 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 O₃ exposures in forested regions of the United States and Canada for the period 1978-1988. We found that the years of highest O₃ 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 O₃ exposure year (i.e., 1979). Consistently throughout the 11-year period, the highest O₃ 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 O₃ 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).     

High Resolution Characterization of Ozone Data for Sites Located in Forested Areas of the United States

Eight years of ambient monitoring data (1978-1985) were used to characterize O₃ concentrations in eight forested areas of the United States. The analysis focused on the annual number of occurrences of hourly averaged O₃ 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 O₃ 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 O₃ 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 O₃ effects research with respect to forested areas and related exposure regimes.     

An Air Quality Data Analysis System for Interrelating Effects,Standards, and Needed Source Reductions: Part 8. An Effective Mean O3 Crop Reduction Mathematical Model

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 O₃ concentration: m_e = [(Σ c_h ^?1/v)/n]^?v, where c_h is the hourly average ambient O₃ 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 O₃ concentration data available in the National Aerometric Data Bank (NADB). County-average effective mean O₃ concentrations are indicated by shading on a U.S. map. State-average O₃ parameters and estimated percent crop yield reductions are tabulated. The National Ambient Air Quality Standard (NAAQS) for O₃ specifies that, on the average, the second highest daily maximum 1-h average O₃ 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 O₃ 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.)     

An air quality data analysis system for interrelating effects, standards, and needed source reductions: Part 11. A lognormal model relating human lung function decrease to O3 exposure

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.     

Use of Plants for Air Pollution Monitoring

Leaf injury data from acute and chronic exposure studies of Dare soybean were regressed against the logarithms of exposure time and O₃ and SO₂ 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 O₃, SO₂, 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 SO₂ effects would be negligible If SO₂ concentrations never exceeded the National Ambient Air Quality Standard (NAAQS) of 0.50 ppm, averaged over 3 h. However, calculations suggest that O₃ may injure up to 24% of Dare soybean leaf surface over a growing season even though the O₃ NAAQS of 0.12 ppm, averaged over 1 h, is never exceeded. Because the 3 h SO₂ standard is exceeded at very few places, the O₃ 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 O₃ concentration (c) measured at an ambient air sampling site over a growing season. This is expressed as: z = -0.0828 + 0.4876 in (Σco₃ ^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.     

Toxicity of Chemical Components of Fine Particles Inhaled by Aged Rats: Effects of Concentration

Abstract

This study tested the hypothesis that exposure to mixtures containing fine particles and ozone (O₃) 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 O₃. Control groups were exposed to purified air or O₃ 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 O₃ alone at 0.2 ppm did not result in significant changes in any of the measured end points. Exposures to the particle mixtures plus O₃ 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 + O₃ mixtures were more toxic than O₃ alone.     

Vegetation exposure to ozone over the continental United States: Assessment of exposure indices by the Eta-CMAQ air quality forecast model

The main use of air quality forecast (AQF) models is to predict ozone (O₃) exceedances of the primary O₃ 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 O₃ exposure indices associated with vegetation using the U.S. AIRNow O₃ observations. These exposure indices include two concentration-based O₃ indices, M7 and M12 (the seasonal means of daytime 7-h and 12-h O₃ concentrations, respectively), and three cumulative exposure-based indices, SUM06 (the sum of all hourly O₃ concentrations ≥ 0.06 ppm), W126 (hourly concentrations weighed by a sigmoidal weighting function), and AOT40 (O₃ 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 O₃ extending from Southern California to Middle Atlantic where the seasonal means, M7 and M12 (the seasonal means of daytime 7-h and 12-h O₃ 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 O₃ 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 O₃ 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 O₃ 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.     

Use of the antiozonant ethylenediurea (EDU) in Italy: verification of the effects of ambient ozone on crop plants and trees and investigation of EDU's mode of action

Twenty-four experiments where EDU was used to protect plants from ozone (O₃) in Italy are reviewed. Doses of 150 and 450 ppm EDU at 2-3 week intervals were successfully applied to alleviate O₃-caused visible injury and growth reductions in crop and forest species respectively. EDU was mainly applied as soil drench to crops and by stem injection or infusion into trees. Visible injury was delayed and reduced but not completely. In investigations on mode of action, EDU was quickly (<2 h) uptaken and translocated to the leaf apoplast where it persisted long (>8 days), as it cannot move via phloem. EDU did not enter cells, suggesting it does not directly affect cell metabolism. EDU delayed senescence, did not affect photosynthesis and foliar nitrogen content, and stimulated antioxidant responses to O₃ exposure. Preliminary results suggest developing an effective soil application method for forest trees is warranted.     

Adaptation by Older Individuals Repeatedly Exposed to 0.45 Parts per Million Ozone for Two Hours

To test for an increased reaction to ozone (O₃) 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 O₃ exposure (0.45 ppm), followed by a fourth O₃ 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 O₃ exposure. Small but significant pre-to-post decrements on the first and second O₃ days in forced vital capacity (FVC—111 and 104 mL), forced expiratory volume in 1 (FEV₁—171 and 164 mL) and 3 seconds (FEV₃—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, FEV₁, OR FEV₃ on the third or fourth day of O₃ 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 O₃ exposure was observed. Changes in small airway response to O₃ (below 75 percent of FVC) without irritant receptor activation, would explain the observed pattern of response.     

Estimated crop yield losses due to surface ozone exposure and economic damage in India

In this study, we estimate yield losses and economic damage of two major crops (winter wheat and rabi rice) due to surface ozone (O₃) exposure using hourly O₃ concentrations for the period 2002–2007 in India. This study estimates crop yield losses according to two indices of O₃ exposure: 7-h seasonal daytime (0900–1600 hours) mean measured O₃ concentration (M7) and AOT40 (accumulation exposure of O₃ concentration over a threshold of 40 parts per billion by volume during daylight hours (0700–1800 hours), established by field studies. Our results indicate that relative yield loss from 5 to 11 % (6–30 %) for winter wheat and 3–6 % (9–16 %) for rabi rice using M7 (AOT40) index of the mean total winter wheat 81 million metric tons (Mt) and rabi rice 12 Mt production per year for the period 2002–2007. The estimated mean crop production loss (CPL) for winter wheat are from 9 to 29 Mt, account for economic cost loss was from 1,222 to 4,091 million US$ annually. Similarly, the mean CPL for rabi rice are from 0.64 to 2.1 Mt, worth 86–276 million US$. Our calculated winter wheat and rabi rice losses agree well with previous results, providing the further evidence that large crop yield losses occurring in India due to current O₃ concentration and further elevated O₃ concentration in future may pose threat to food security.     

Co-occurrence patterns of gaseous air pollutant pairs at different minimum concentrations in the United States

The frequency of co-occurrences for SO₂NO₂, SO₂/O₃ and O₃/NO₂ at rural and remote monitoring sites in the United States was characterized for the months of May-September for the years 1978–1982. Minimum hourly concentrations of 0.03 and 0.05 ppm of each gas were used as the criteria for defining a ‘co-occurrence’. The objectives of this study were to:

• 1.(1) identify the types of co-occurrence patterns and their frequency;
• 2.(2) identify whether the frequency of hourly simultaneous co-occurrences increased substantially when the minimum concentration was lowered (e.g. from 0.05 to 0.03 ppm) for each pollutant; and
• 3.(3) determine whether the frequency of co-occurrences showed large year-to-year variation.

For all pollutant pairs and co-occurrence thresholds (i.e. 0.03 and 0.05 ppm), the frequency of daily and hourly co-occurrences was low for most sites. Year-to-year variability was found to be insignificant; most of the monitoring sites experienced co-occurrences of any type less than 12% of the 153 days. Based on our observations, researchers attempting to assess the potential effects of SO₂/NO₂, SO₂/O₃ and O₃/NO₂ in the United States should construct simulated exposure regimes so that

• 1.(1) hourly simultaneous and daily simultaneous-only co-occurrences are fairly rare and
• 2.(2) when co-occurrences are present, complex-sequential and sequential-only co-occurrence patterns predominate.

     

The influence of ozone exposure dynamics on the growth and yield of kidney bean

A field experiment was conducted in open-top chambers to assess the importance of peak exposure concentration and exposure frequency on the responses of kidney bean plants to O3. There were five treatments in the study: charcoal-filtered air, constant exposure to 0.05 ppm O3 (131 microg m(-3)) daily. fluctuating exposure to 0.08 ppm O3 on three alternate days, cluster exposure to 0.08 ppm O3 on three consecutive days, and peak exposure to 0.12 ppm O3 on two consecutive days. Exposures lasted 4 h and produced an average weekly exposure-period concentration of approximately 0.05 ppm in the O3-addition treatments and 0.025 ppm in the charcoal-filtered treatment. Exposures began on June 23 and terminated on September 8. Plants were harvested weekly and assessed for the number, area, and dry mass of leaves; dry mass of stems; dry mass of roots; the number of pods; and the incidence of foliar O3 injury. Yield was assessed at the end of the study. There were no consistent differences between the plants receiving charcoal-filtered air and those receiving O3 exposure. Significant differences were detected among the treatments for several of the growth variables assessed at the interim harvests, but in the final two harvests these differences had mostly disappeared. There were no significant effects of the O3-addition treatments on yield when compared to the plants receiving charcoal-filtered air. This indicates that there were no cumulative impacts on plants exposed to 0.12 ppm O3 for 4 h on two consecutive days followed by filtered air compared to plants receiving charcoal-filtered air. The seasonal 7-h average concentrations of O3 in the peak and filtered air treatments were approximately 0.040 and 0.025 ppm, respectively.     

Effects of Chronic Doses of Ozone on Field-Grown Loblolly Pine: Seedling Responses in the First Year

A study was designed to examine responses of loblolly pine (Pinus taeda) to chronic exposure to ozone (O₃) in the field. Seedlings of four full-sib families of loblolly pine were planted in a field near Raleigh, NC, and exposed daily (May 27 to October 24, 1985) in open-top chambers to O₃ ranging from 0.5 to 1.96 times the O₃ concentration in non-filtered (NF) air. One-fourth of the plants in each plot were removed during each of two harvests (August and October) to measure effects of O₃ on plant growth. Plants of each family exhibited foliar symptoms characteristic of O3 injury after five months of exposure to any greater-than-ambient O₃ concentration, and one family exhibited symptoms after five months of exposure to NF air. Ozone dose-plant response relationships were quantified by regression for stem height, stem diameter, biomass, and other plant morphological and yield characteristics. All relationships were linear for three families, but one family exhibited no significant growth response relationship of O₃ dose. Dose-response equations suggest a maximum growth suppression of 10 percent for NF air compared to charcoal-filtered air (i.e., 0.5 × NF) in the first season of exposure.     

Effects of chronic ozone exposure on growth, root respiration and nutrient uptake of rice plants

To clarify the response of growth and root functions to low concentrations of ozone (O(3)), rice plants (Oryza sativa L.) were exposed to O(3) at 0.0 (control), 0.05 and 0.10 ppm for 8 weeks from vegetative to early heading stages. Exposure to 0.05 ppm O(3) tended to slightly stimulate the dry weight of whole plants up to 5 weeks and then slightly decrease the dry weight of whole plants. However, these effects were statistically significant only at 6 weeks. Exposure to 0.10 ppm O(3) reduced the dry weight of whole plants by 50% at 5 and 6 weeks, and thereafter the reduction of the dry weight of whole plants was gradually alleviated. Those changes in dry weight can be accounted for by a decrease or increase in the relative growth rate (RGR). The changes in the RGR caused by 0.05 and 0.10 ppm O(3) could be mainly attributed to the effect of O(3) on the net assimilation rate. Root/shoot ratio was lowered by both 0.05 and 0.10 ppm O(3) throughout the exposure period. The root/shoot ratio which had severely decreased at 0.10 ppm O(3) in the first half period of exposure (1-4 weeks) became close to the control in the latter part of exposure (5-8 weeks). Time-course changes in NH(4)-N root uptake rate were similar to those in the root/shoot ratio especially for 0.10 ppm O(3). On the other hand, root respiration increased from the middle to later periods. Since it is to be supposed that plants grown under stressed conditions change the ratio of plant organ weight to achieve balance between the proportion of shoots to roots in the plant and their activity for maintaining plant growth, these changes in root/shoot ratio and nitrogen uptake rate under long-term exposure can be considered to be an adaptive response to maintain rice growth under O(3) stress.     

Effects of Gaseous Air Pollutants on Gastric Secreto-Motor Activities in the Rat

A study was initiated to ascertain whether gaseous air pollutants can influence gastric secreto-motor activities. The investigation was conducted to determine the effect of various exposures to S0₂, N0₂, CO, and 0₃ on gastric motor activity of the conscious unrestrained rat by means of a chronic intragastric bajloon. Tfie effects produced upon gastric secretory volume and total titratable acid secretion produced by these gases were also studied in rats which were pylorus-ligated subsequent to exposure. Rats exposed to 1 ppm S0₂ for 5 days, 60 ppm CO for 2 hours, 0.5 ppm N0₂ for 2 hours, or 0.25 ppm 0₃ for 2 hours showed no change while there was gastric inhibition at 300 ppm S0₂ for 2 hours, 1400 ppm CO for 1 hour, 26 ppm N0₂ for 2 hours and 1.5 ppm 0₃ for 2 hours. In most instances following chamber flushing recovery was complete within minutes. To evaluate the site and nature of stimulation, rats were also exposed to oil of mustard, benzaldehyde, hydrogen peroxide, amyl acetate, and “Old Spice” after sh ave lotion. Saturated dental paper points were introduced without obstruction into tracheal and retro-nasal cannulae. Oil of mustard but not benzaldehyde or amyl acetate inhibited gastric motility only when applied to the trachea. In general, the drop in activity was immediate and proportional to the degree of exposure. Nasal irritation was ineffective in eliciting the response. The experimental results lead to the following conclusions: 1) Toxic levels of these gases are associated with an inhibition of gastric motility that is not produced by .exposure of the nasal passages alone to the gases. 2) Toxic levels of these gases produced no demonstrable effect upon either total gastric acid secretion or total secretory volume. These findings tend to confirm earlier observations of an association between exposure to toxic concentrations of S0₂ and loss of gastric tone in the rodent stomach.     

COS,CS2 and SO2 in aluminium smelter exhaust

Measurements of carbonyl sulfide (COS) and carbondisulfide (CS₂) were carried out on samples drawn from a smoke stack of an aluminium smelter. Volume mixing ratios of 6 ppm COS and 0.1 ppm CS₂ were measured for gases from the electrolysis unit that had previously passed an Al₂O₃ fluid bed reactor and electrostatic precipitators. Specific emissions of 1.6 kg COS and 0.03 kg CS₂ per ton of primary aluminium were found. Extrapolating from this particular smelter’s conditions to a world mix specific COS emissions of about 4 kg/t(Al) are calculated resulting in emissions of annually 0.08 Tg COS into the atmosphere due to electrolytic aluminium production in 1995. Besides the photochemical conversion of anthropogenic CS₂ aluminium production is established to be the second major industrial source of COS probably exceeding automotive tire wear’s and coal combustion’s contributions.     

Demonstrating attainment in Atlanta using urban airshed model simulations: impact of boundary conditions and alternative forms of the NAAQS

Urban Airshed Model-Version IV (UAM-IV) simulations on 7–8 July, 1988 for the Atlanta, Georgia, nonattainment area are used to investigate how recent changes in the National Ambient Air Quality Standard (NAAQS) and changes in boundary concentrations may affect attempts to comply with the standard through local emissions reductions. According to model results, the recently promulgated 8 h NAAQS at a level of 0.08 ppmv will require larger emission reductions to comply with the standard than those that are necessary to comply with the previous 1 h/0.12 ppmv NAAQS. Regardless of the form of the NAAQS or the magnitude of the concentrations of O₃ and its precursors at the model domain boundary, UAM-IV simulations for Atlanta predict that NO_x (NO+NO₂) emission reductions are more effective than volatile organic compound reductions in mitigating O₃ pollution. Moreover, the simulations indicate that NO_x emission reductions greater than 60–75% would be required to demonstrate attainment under either form of the standard, even if boundary concentrations of O₃ and its precursors were substantially reduced. Further research is necessary to determine if this weak response to emission controls is truly representative of the real atmosphere, or is a result of the meteorological conditions specific to this episode, or is an artifact of the UAM-IV model or its inputs.