Air Sampling Sites Research Articles

Complexation of trace metals in size-segregated aerosol particles at nine sites in Germany

The complexation of trace metal ions (TMI) was studied in size-segregated ambient aerosol particles collected at nine sites in Germany (urban, rural and coastal). Samples were analysed in terms of TMI (Fe, Mn, Cu), potential inorganic and organic ligands and pH. Using a thermodynamic model (E-AIM III), the concentrations of these compounds in the particle liquid phase were estimated. The resulting liquid phase concentrations were then used as input parameters for a speciation model (Visual MINTEQ) and the equilibrium complexation was calculated under realistic conditions. The complexation was found to be controlled by the availability of strong organic ligands, especially oxalate, whose occurrence in turn was governed by the formation of insoluble Ca-oxalate. Likewise, the pH influenced oxalate availability because it alters the concentrations of the chelating mono- and dianions. As a qualitative result, Fe3+ was found to be mainly complexed by oxalate, while Fe2+ and Mn2+ were rather associated with nitrate. Cu2+ showed mixed organic and nitrate complexation. Complexation by HULIS was only significant for Fe3+ and Cu2+ and was generally less important than other ligands like oxalate and nitrate. Oxalate was found to exist mainly in the solid phase while higher dicarboxylic acids mostly did not form complexes due to protonation. Complexation was shown to be influenced by season, air mass origin, particle size and sampling site.

Spatial and temporal variation and air–soil exchange of atmospheric PAHs and PCBs in an industrial region

It was recently suggested that emissions of some persistent organic pollutants (POPs) are decreasing in former use regions due to emission reductions combined with uncontrolled export, at the expense of regions receiving these substances as obsolete products and wastes. Aliaga industrial region in Izmir, Turkey is one of the regions receiving POPs in the form of scrap iron and old ships to be scrapped. Ambient air samples were collected by passive sampling during four seasons in 2009 and 2010 (winter, spring, summer, and fall) at forty different sites in Aliaga to determine the spatial and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Soil samples were also collected at the air sampling sites during the summer period. Phenanthrene was the most abundant PAH at all sites, and all samples were dominated by low to medium molecular weight PAHs, i.e., fluorene, fluoranthene and pyrene. The spatial distribution of ambient PAH concentrations indicated that the major PAH sources in the region were iron–steel plants, petroleum refinery, and ship dismantling plants. At residential sites, PAH concentrations were higher in winter indicating that wintertime concentrations were mainly affected by residential heating emissions. However, highest atmospheric PCBs concentrations were observed in summer, probably due to increased volatilization from their sources at higher temperatures. Low to medium molecular weight PCBs (tri–, tetra–, penta–CBs) were the most abundant compounds in air for all seasons. Results also indicated that iron–steel plants and ship dismantling facilities were the major PCB emitters in the region. A similar spatial variation was observed for soil PAH and PCB concentrations. Air and soil PAH and PCB concentrations were correlated significantly indicating the interaction of these compartments. Results of the fugacity ratio calculations indicated that local soils generally act as a sink throughout the year for medium to low volatility atmospheric PAHs and PCBs. However, during summer soil becomes a source, especially for volatile PAHs and PCBs.

Airborne concentrations of bacteria and fungi in Thailand border market

Thailand border market is where the local Thais, Cambodians, Laotians, and Burmeses exchange their goods and culture at the border checkpoints. It is considered to be the source of aerial disease transmission especially for foreigners because it is always very crowded with people from all walks of life. Unhealthy air quality makes this area high risk of spread of airborne diseases. This study assessed airborne concentrations of bacteria and fungi in a border market to improve exposure estimates and develop efficient control strategies to reduce health risk. The density and distribution of airborne bacteria and fungi were investigated in the Chong Chom border market in Surin Province, Thailand. Eighteen air sampling sites were taken from outdoors and various work environments including indoor footpaths, wooden handicraft shops, electronic shops, the secondhand clothing shops, and fruit market areas. Exposed Petri plate method and liquid impinger sampler were used for sampling at the breathing zone, 1.5 m above the floor level, during weekend and holiday. Meteorological factors such as relative humidity, temperature, and light intensity were collected by portable data logger. The relative humidity was 67–73%, and temperature 29–33°C, and light varied between 18 and 270 Lux m−2. Gram-positive and Gram-negative bacteria were found at a mean value of 104 CFU m−3, and airborne fungi of 103 CFU m−3 were recorded. The highest concentration of culturable airborne microorganisms was found along the indoor footpath (9.62 × 104 CFU m−3 and 750.00 CFU/plate/h for impingement and sedimentation methods, respectively), the fruit market area (7.86 × 104 CFU m−3 and 592.42 CFU/plate/h for impingement and sedimentation methods, respectively), and the secondhand clothing shop (4.59 × 103 CFU m−3 and 335.42 CFU/plate/h for impingement and sedimentation methods, respectively) for Gram-positive bacteria, Gram-negative bacteria, and fungi, respectively. The lowest concentration of Gram-positive bacteria, Gram-negative bacteria, and fungi was found only at the outdoor area at 1.53 × 104 CFU m−3, 0.93 × 104 CFU m−3 and 0.80 × 103 CFU m−3 by means of impingement method and 136.67 CFU/plate/h, 69.25 CFU/plate/h, and 62.00 CFU/plate/h by means of sedimentation methods for Gram-positive bacteria, Gram-negative bacteria, and fungi, respectively. The most frequently present airborne bacteria were identified as Bacillus, Corynebacteria, Diplococcus, Micrococcus, Acinetobacter, Alcaligenes, Enterobacter, and spore former rods. Acremonium, Aspergillus, Cladosporium, Penicillium, and Sporotrichum were the most frequently found aerosol fungi genera. The distribution of airborne microorganisms correlated with relative humidity and light factors based on principal component analysis. In conclusion, the border market is a potential source of aerial disease transmission and a various hazards of bioaerosols for workers, consumers, sellers, and tourists. The bioaerosol concentration exceeded the standard of occupational exposure limit. Many major indicators of allergenic and toxigenic airborne bacteria and fungi, Acinetobacter, Enterobacter, Pseudomonas, Cladosporium, Alternaria, Aspergillus, and Penicillium, were found in the various market environments.

Three methods for quantifying proximity of air sampling sites to spatially resolved emissions of semi-volatile organic contaminants

Passive air samplers have made it possible to measure long-term average air concentrations of semi-volatile organic contaminants (SVOCs) at a large number of sampling sites. In order to use the results of such measurement networks in the derivation of empirical measures of long-range transport, a method is required that quantitatively expresses the proximity of air sampling sites to spatially distributed emissions. We propose three increasingly sophisticated tiers for quantifying proximity to emissions. The ‘static’ method assumes that a sampling site is only influenced by emission taking place in the same 1° of latitude by 1° of longitude cell in which it is located. The ‘dispersion’ method additionally accounts for the influence of emissions in neighboring cells by adding the emissions into each cell weighted by the distance between the cell’s center and the center of the cell containing the sampling site. The ‘air-shed’ method quantifies proximity to emissions by combining the emissions in each cell with the probability that air arriving at the sampling site passed through each cell. The probability is calculated for each sampling site by aggregating a large number of air mass back-trajectories. These new proximity gauges were contrasted against the remoteness index RI, which is derived from global atmospheric tracer transport modeling. The four methods were used to quantify the proximity of the sampling sites of the Global Atmospheric Passive Sampling (GAPS) study to global Polycyclic Aromatic Hydrocarbon (PAH) emissions. The proximity gauges produce markedly different results primarily for sites located near steep gradients in population, such as occur in coastal areas or at the feet of mountain ranges. The dispersion method produces quite similar results to the air-shed method using drastically less computational power and input data, but application of the air-shed method may be necessary where winds are strongly directional.

Monitoring and Identification of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in the Ambient Central Taiwan

Polychlorinated Dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) in the ambient air of five sampling sites around central Taiwan were investigated. Principal components analysis (PCA), cluster analysis (CA) and the chemical mass balance (CMB) model were adopted to assess possible PCDD/F sources and their effects on the air quality levels. Field experimental results showed that the mean PCDD/F concentrations in the ambient air were 0.0526, 0.0591, 0.0339 and 0.0727 pg I-TEQ/Nm^3 in winter, spring, summer and autumn, respectively. Analysis of atmospheric isopleths for five sampling sites displayed that high PCDD/F concentrations were mostly close to electric arc furnace plants (EAF). Through PCA and CA, the congener profiles of ambient air sampling sites were close to medical waste incinerators (MWI), secondary aluminum smelters (ALS), EAF, waste open burning (OB) and crematories (CM). By using the CMB model, the dominant sources of PCDD/Fs in ambient air were EAF, medical waste incinerator/municipal solid waste incinerators (MWI/MSWI) and unleaded gasoline fuel vehicle/diesel fuel vehicle (UGFV/DFV), which contributed 22-23%, 17-31% and 9-22%, respectively. The above results revealed that ambient air was affected by surrounding PCDD/F sources (MWI, ALS, EAF, CM and OB). However, due to high stack height and low emission concentration, the impact of coal-fired power plant on the PCDD/F levels of ambient air was insignificant.

Enantiomeric Signatures of Organochlorine Pesticides in Asian, Trans-Pacific, and Western U.S. Air Masses

The enantiomeric signatures of organochlorine pesticides were measured in air masses from Okinawa, Japan and three remote locations in the Pacific Northwestern United States: Cheeka Peak Observatory (CPO), a marine boundary layer site on the Olympic Peninsula of Washington at 500 m above sea level (m.a.s.l); Mary's Peak Observatory (MPO), a site at 1250 m.a.s.l in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2763 m.a.s.l in Oregon's Cascade range. The enantiomeric signatures of composite soil samples, collected from China, South Korea, and the western U.S. were also measured. The data from chiral analysis was expressed asthe enantiomeric fraction, defined as (+) enantiomer/(sum of the (+) and (-) enantiomers), where a racemic composition has EF = 0.5. Racemic alpha-hexachlorocyclohexane (alpha-HCH) was measured in Asian air masses at Okinawa and in Chinese and South Korean soils. Nonracemic alpha-HCH (EF = 0.528 +/- 0.0048) was measured in regional air masses at CPO, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the alpha-HCH EFs were significantly more racemic (EF = 0.513 +/- 0.0003, p < 0.001). Racemic alpha-HCH was consistently measured at MPO and MBO in trans-Pacific air masses that had spent considerable time in the free troposphere. The alpha-HCH EFs in CPO, MPO, and MBO air masses were negatively correlated (p = 0.0017) with the amount of time the air mass spent above the boundary layer, along the 10-day back air mass trajectory, prior to being sampled. This suggests that, on the West coast of the U.S., the alpha-HCH in the free troposphere is racemic. Racemic signatures of cis- and trans-chlordane were measured in air masses at all four air sampling sites, suggesting that Asian and U.S. urban areas continue to be sources of chlordane that has not yet been biotransformed.

Assessment of airborne microorganism contamination in an industrial area characterized by an open composting facility and a wastewater treatment plant

In order to assess the potential exposure hazard to workers and people living in the immediate surroundings of an area characterized by an open composting facility and a wastewater treatment plant, a quantitative and a qualitative analysis of airborne microorganisms were carried out. Air sampling was performed once a week for four consecutive weeks in summer and winter. Six sites were selected as air sampling sites: one was upwind at approximately 40 m from the facilities; the other five were downwind at increasing distances from the facilities, with the furthest at 100 m away. Monitoring permitted us to verify the influence that the composting activities and wastewater treatment had on the bacterial and fungal contamination of the air. The results obtained have been expressed by means of contamination indexes that have already been used in previous works: a major microbiological contamination near the plants was evidenced. Near the facilities, mesophilic bacteria, psychrophilic bacteria and microfungi showed the highest median concentrations, respectively, of 307.5, 327.5 and 257.5 CFU/m 3. Moreover, the season generally influenced the concentration of the bacteria as well as of the fungi; higher in summer than in winter. The contamination index global index of microbial contamination (GIMC/m 3) showed mean values of 4058.9 in summer and 439.7 in winter and the contamination index—amplification index (AI) showed values of 4.5 and 1.1 in the same seasons, respectively. Controlling the seasonal effect, mesophilic bacteria, Pseudomonas spp. and Enterobacteriaceae showed a significant decline in concentration with respect to upwind air samples and with increasing distance. Both GIMC and AI showed a significant decline with respect to upwind air samples by increasing the distance from facilities after adjusting for the seasonal effect. In conclusion, even if these plants do not represent a potential risk for nearby populations, they may pose a potential health risk for workers.

A Review of Land-use Regression Models for Characterizing Intraurban Air Pollution Exposure

Epidemiologic studies of air pollution require accurate exposure assessments at unmonitored locations in order to minimize exposure misclassification. One approach gaining considerable interest is the land-use regression (LUR) model. Generally, the LUR model has been utilized to characterize air pollution exposure and health effects for individuals residing within urban areas. The objective of this article is to briefly summarize the history and application of LUR models to date outlining similarities and differences of the variables included in the model, model development, and model validation. There were 6 studies available for a total of 12 LUR models. Our findings indicated that among these studies, the four primary classes of variables used were road type, traffic count, elevation, and land cover. Of these four, traffic count was generally the most important. The model R2 explaining the variability in the exposure estimates for these LUR models ranged from.54 to.81. The number of air sampling sites generating the exposure estimates, however, was not correlated with the model R2 suggesting that the locations of the sampling sites may be of greater importance than the total number of sites. The primary conclusion of this study is that LUR models are an important tool for integrating traffic and geographic information to characterize variability in exposures.

Tropospheric Phosphine and Its Sources in Coastal Antarctica

Earlier reports show very low concentrations of phosphine in remote air of the lower troposphere of nonpolar regions, in the low ng m(-3) range during the night and in the pg m(-3) range during daylight around noon. In this study, abnormally and unexpectedly high phosphine concentrations (30.0-407.8 ng m(-3), 11 locations) were found in polar air samples collected on Millor Peninsula, eastern Antarctica and Fildes Peninsula, western Antarctica. The maximum concentration was measured in the atmosphere of penguin colonies. Field phosphine emission rates from four colonies were 8.99 ng m(-2) h(-1) (skua colony), 9.56 ng m(-2) h(-1) (gentoo penguin colony), 39.96 ng m-2 h-' (seal colony) and 63.58 ng m(-2) h(-1) (empire penguin colony), respectively. Our air sampling sites are located downwind of two large penguin colonies, indicating that penguin colony emission is the predominant source for atmospheric PH3 on Millor Peninsula. Laboratory scale incubation of ornithogenic soils amended by penguin guanos yielded a maximum PH3 production rate of 0.58 ng kg(-1) d(-1) specifically at low temperature (4 degrees C). Significant concentrations of phosphine occur in the atmosphere of coastal Antarctica and confirm the existence of a small gaseous link in the phosphorus cycle of the Antarctic tundra ecosystem.

Ambient air quality of Kathmandu valley as reflected by atmospheric particulate matter concentrations (PM10)

This paper presents the analysis and interpretation of ambient particulate matter concentrations measured as PM10 at a network of six air monitoring stations in Kathmandu valley during the years, 2003 through 2005. The purpose was to understand the pollution trends associated with different areas considering levels particulate matter concentrations representing the ambient air quality of Kathmandu valley. The study indicate that particulate concentrations (PM10) measured are persistently higher at air sampling sites representing roadside areas compared to the background sites. The inter-station network variability with respect the particulate pollution suggests optimizing resources. The comparison of annual average PM10 concentration observed at six air-monitoring sites in Kathmandu Valley with standard annual average concentration prescribed by World Health Organization as well as Europe Union indicates serious PM10 pollution in Kathmandu valley.

Effects of Reformulated Gasoline and Motor Vehicle Fleet Turnover on Emissions and Ambient Concentrations of Benzene

Gasoline-powered motor vehicles are a major source of toxic air contaminants such as benzene. Emissions from light-duty vehicles were measured in a San Francisco area highway tunnel during summers 1991, 1994-1997, 1999, 2001, and 2004. Benzene emission rates decreased over this time period, with a large (54 +/- 5%) decrease observed between 1995 and 1996 when California phase 2 reformulated gasoline (RFG) was introduced. We attribute this one-year change in benzene mainly to RFG effects: 36% from lower aromatics in gasoline that led to a lower benzene mass fraction in vehicle emissions, 14% due to RFG effects on total nonmethane organic compound mass emissions, and the remaining 4% due to fleet turnover. Fleet turnover effects accumulate over longer time periods: between 1995 and 2004, fleet turnover led to a 32% reduction in the benzene emission rate. A approximately 4 microg m(-3) decrease in benzene concentrations was observed at a network of ambient air sampling sites in the San Francisco Bay area between the late 1980s and 2004. The largest decrease in annual average ambient benzene concentrations (1.5 +/- 0.7 microg m(-3) or 42 +/- 19%) was observed between 1995 and 1996. The reduction in ambient benzene between spring/summer months of 1995 and 1996 due to phase 2 RFG was larger (60 +/- 20%). Effects of fuel changes on benzene during fall/winter months are difficult to quantify because some wintertime fuel changes had already occurred prior to 1995.

The role of carbon dioxide in climate forcing from 1979 to 2004: introduction of the Annual Greenhouse Gas Index

High-precision measurements of CO2, CH4, N2O, CFC-12, CFC-11 (major greenhouse gases) and 10 minor halogenated gases from a globally distributed network of air sampling sites are used to calculate changes in radiative climate forcing since the pre-industrial era (1750) for the period of measurement, 1979–2004. The five major greenhouse gases account for about 97% of the direct radiative forcing by long-lived gases. The fraction of the sum of radiative forcings by all long-lived gases that is due to CO2 has grown from 60% to 63% over this time. Though the long-term increase in this sum is due primarily to increased anthropogenic emissions of these radiatively important gases, interannual variations in the growth rate of radiative forcing due to CO2 are large and likely related to natural phenomena such as volcanic eruptions and ENSO events. The annual value of the total global radiative forcing of the long-lived gases is used to define an Annual Greenhouse Gas Index (AGGI). The AGGI is normalized to 1990, the Kyoto Protocol baseline year.

Atmospheric methane levels off: Temporary pause or a new steady‐state?

The globally‐averaged atmospheric methane abundance determined from an extensive network of surface air sampling sites was constant at ∼1751 ppb from 1999 through 2002. Assuming that the methane lifetime has been constant, this implies that during this 4‐year period the global methane budget has been at steady state. We also observed a significant decrease in the difference between northern and southern polar zonal annual averages of CH4 from 1991 to 1992. Using a 3‐D transport model, we show that this change is consistent with a decrease in CH4 emissions of ∼10 Tg CH4 from north of 50°N in the early‐1990s. This decrease in emissions may have accelerated the global methane budget towards steady state. Based on current knowledge of the global methane budget and how it has changed with time, it is not possible to tell if the atmospheric methane burden has peaked, or if we are only observing a persistent, but temporary pause in its increase.

Measurements of an anomalous global methane increase during 1998

Measurements of atmospheric methane from a globally distributed network of air sampling sites indicate that the globally averaged CH4 growth rate increased from an average of 3.9 ppb yr−1 during 1995–1997 to 12.7±0.6 ppb in 1998. The global growth rate then decreased to 2.6±0.6 ppb during 1999, indicating that the large increase in 1998 was not a return to the larger growth rates observed during the late‐1970s and early‐1980s. The increased growth rate during 1998 corresponds to an increase in the imbalance between CH4 sources and sinks equal to ∼24 Tg CH4, the largest perturbation observed in 16 years of measurements. We suggest that wetland and boreal biomass burning sources may have contributed to the anomaly. An adaptation of a global process‐based model, which included soil‐temperature and precipitation anomalies, was used to calculate emission anomalies of 11.6 Tg CH4 from wetlands north of 30°N and 13 Tg CH4 for tropical wetlands during 1998 compared to average emissions calculated for 1982–1993. For 1999, calculated wetland emission anomalies were negative for high northern latitudes and the tropics, contributing to the low growth rate observed in 1999. Also 1998 was a severe fire year in boreal regions where ∼1.3 × 105 km² of forest and peat land burned releasing an estimated 5.7 Tg CH4.

Toward an Understanding of the Global Atmospheric Distribution of Persistent Organic Pollutants: The Use of Semipermeable Membrane Devices as Time-Integrated Passive Samplers

Triolein-containing semipermeable membrane devices (SPMDs) were deployed as passive air samplers alongside conventional air samplers at two sites, and derived atmospheric concentrations from each were compared. Excellent comparability was noted between sampling systems. SPMDs were also deployed for 2 years at 10 sites across a latitudinal transect from the south of the U.K. (ca. 50° N) to the north of Norway (ca. 70° N) to passively sample air. Time-integrated, simultaneous data were obtained, which were used to test the global fractionation hypothesis in the Northern Hemisphere. Extracts were analyzed for a suite of PCB congeners and α- and γ-HCH. A latitudinal change in PCB profiles was seen. The absolute atmospheric concentration of the tetra-chlorinated PCBs was relatively uniform over the study area (ca. 1.9 pg m-3), but their relative concentration increased with increasing latitude or decreasing temperature (12% of total PCB concentrations in the south of the U.K. as compared with 35% at the northern-most station). The concentration of the penta-chlorinated PCBs decreased from 6 pg m-3 at the southern U.K. site to 1.5 pg m-3 in the north of Norway, but their relative concentration was uniform (33% total PCB) over the transect. Absolute and relative concentrations of heavier PCBs decreased with increasing latitude and decreasing temperature. These data indicate that a temperature-controlled fractionation of PCBs is occurring in the atmosphere. Data were available for soil PCB concentrations at or near seven of the air sampling sites. Fugacity quotients suggested that across the study area the air/soil system is at or near to equilibrium for PCBs. Concentrations of the α-HCH isomer sequestered by the SPMDs increased from south to north while the sequestered γ-HCH concentrations decreased. The ratio of α/γ-HCH increased by a factor of approximately 20 from the south to the north of the study area. These data are consistent with the selective weathering of thesecompounds during their long-range atmospheric transport from southerly source regions to remote northern locations.

Atmospheric circulation around the Greenland Crest

The Greenland Ice Sheet Program 2 (GISP2) required meteorological support for the layout of the field camp, ice core site, landing strip, snow sampling sites, and air sampling sites. An automatic weather station installed in May 1987 provided the initial data for the support of several components of the program using the 2 year wind speed and direction distributions. The automatic weather station (AWS) network was expanded to six sites with four sites located approximately 100 km from the highest point in Greenland in the cardinal directions and sites located at GISP2 and at the air sampling site. The wind direction and speed wind roses for August and September 1994 show that there is considerable variation in the wind field around the Greenland Crest. The constancy (ratio of the vector wind speed to the scalar wind speed) of the monthly wind vectors was lowest at the southern site and increased as one moved clockwise around the crest to the eastern site. Vorticity and divergence were determined from triangles formed by three AWS sites. The mean horizontal divergence for August and September 1994 was 1.4×10−5 s−1, and the vorticity was −3.7×l0−5 s−1. Apparently, the flow around the Greenland Crest is most influenced by topography when the 500 hPa contours indicate a pressure ridge over central Greenland. The surface winds showed anticyclonic flow, positive horizontal divergence, and negative vertical vorticity. In the mean, this configuration indicates the presence of an inversion wind, especially at the sites located on the slopes to the west and east of the crest.

Comment on ‘A dramatic decrease in the growth rate of atmospheric methane in the northern hemisphere during 1992' by E. J. Dlugokencky et al.

The carefully measured decrease in the growth rate of atmospheric methane (CH4) in 1992 reported by Dlugokencky et al. (1994) is an impressive accomplishment, and testimony for the importance of maintaining high-quality, long-term monitoring of atmospheric composition. The changing growth rate of atmospheric CH4 has important implications for assessing and understanding the potential magnitude and rates of a future greenhouse gas-induced climate change. Furthermore, the CH4 data from the current Climate Monitoring and Diagnostics Laboratory (CMDL) globally-distributed network of cooperative air sampling sites are clearly the best record of global CH4 trends and distribution currently available. However, we argue briefly here that the speculation by Dlugokencky et al. (1994) on possible mechanisms for the decreased growth rate in 1992 is only one scenario of many that could possibly fit with the constraints imposed by the reported data. Our comments are to (1) illustrate the difficulties of deducing small changes in complex, poorly understood, geographically diverse natural and anthropogenic sources of CH4 from measurements at the remotely-located CMDL sampling sites and (2) emphasize that detailed bottoms-up analyses are necessary to really advance the understanding of changes in source strengths; we are not promoting alternative mechanisms to explain the 1992 decrease in atmospheric CH4.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 8. An Effective Mean O3Crop 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: me = [(Σ ch −1/v)/n]−v, where ch 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 (tme 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 ta...

Exposure of Hospital Workers to Airborne Antineoplastic Agents

Practices for handling antineoplastic drugs were surveyed, and ambient-air sampling for four antineoplastic agents was conducted in outpatient oncology clinics. A questionnaire was administered in 1981 to the nurse or pharmacist in charge of drug preparation at 10 hospital oncology clinics. At three sites, air samples were collected during working hours in medication-preparation rooms and nearby offices. The air-sampling pumps contained filters at breathing-zone height; room air was drawn through each filter for 40 hours. Extracts from the filters were assayed by high-performance liquid chromatography (HPLC) for fluorouracil and cyclophosphamide in seven sets of samples and methotrexate and doxorubicin in five sets of samples. Mass spectrometry (MS) was used to confirm detection of fluorouracil. Total use of each monitored drug was recorded at each site. Nine clinics had no ventilation hood, and drugs were prepared by nurses in eight clinics. Routine use of gloves (three clinics) and masks (one clinic) was uncommon, and wastes were disposed of in uncovered receptacles in four of the clinics. Eating and drinking occurred in seven of the preparation rooms. At the main air-sampling site, fluorouracil (0.12-82.26 ng/cu m) was detected in air during 200 of the 320 hours monitored. Cyclophosphamide (370 ng/cu m) was present during 80 hours. In the two other sites, fluorouracil was detected by HPLC but not confirmed by MS, and no cyclophosphamide was detected. No detectable amounts of methotrexate and doxorubicin were present. Fluorouracil was the most frequently used drug, and cyclophosphamide was second. Results suggest that personnel handling antineoplastic drugs are subject to potential systemic absorption of these agents by inhalation.

An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 7. An O3-SO2Leaf Injury Mathematical Model

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.