Impacts of a strong cold front on concentrations of HONO,HCHO, O3, and NO2 in the heavy traffic urban area of Beijing

Much rain and strong winds caused by a cold front occurred in Beijing during the period of Sep. 27 to Oct. 4, 2004 and led to sharp drops in maximum and mean concentrations of HONO, HCHO, O₃, and NO₂, i.e., the maximum concentrations were reduced by 5.9, 21.3, 45.6, and 44.4 ppb, respectively, and the mean concentrations were decreased by 4.0, 5.5, 30.3, and 32.3 ppb, respectively. For daily HO_x production rates HONO photolysis was the largest contributor and over 90% contributions were from photolysis of HONO and HCHO. Large number and area percentages of soot aggregate from PM10, and high correlations between concentrations of PM10 and chemical formation of HONO suggested that heterogeneous reactions of NO₂ on surfaces of soot aggregate could be a key source of HONO in the heavy traffic areas of Beijing during the night and should be considered in air quality simulations for such areas.     

Ozone exposure of field-grown winter wheat affects soil mesofauna in the rhizosphere

A 2-year open-top chamber experiment with field-grown winter wheat (Triticum aestivum L. cv. Astron) was conducted to examine the effects of ozone on plant growth and selected groups of soil mesofauna in the rhizosphere. From May through June in each year, plants were exposed to two levels of O₃: non-filtered (NF) ambient air or NF+ 40 ppb O₃ (NF+). During O₃ exposure, soil sampling was performed at two dates according to different plant growth stages. O₃ exposure reduced above- and below-ground plant biomass in the first year, but had little effect in the second year. The individual density of enchytraeids, collembolans and soil mites decreased significantly in the rhizosphere of plants exposed to NF+ in both years. Differences were highest around anthesis, i.e. when plants are physiologically most active. The results suggest that elevated O₃ concentrations may influence the dynamic of decomposition processes and the turnover of nutrients.     

Growth and nutritive quality of Poa pratensis as influenced by ozone and competition

Interspecific plant competition has been hypothesized to alter effects of early-season ozone (O3) stress. A phytometer-based approach was utilized to investigate O3 effects on growth and nutritive quality of Poa pratensis grown in monoculture and in mixed cultures with four competitor-plant species (Anthoxanthum odoratum, Achillea millefolium, Rumex acetosa and Veronica chamaedrys). Mesocosms were exposed during April/May 2000-2002 to charcoal-filtered air+25 ppb O3 (control) or non-filtered air+50 ppb O3 (elevated O3). Biomass production was not affected by O3, but foliar injury symptoms were observed in May 2002. Early-season O3 exposure decreased relative food value of P. pratensis by an average of 8%, which is sufficient to have nutritional implications for its utilization by herbivores. However, forage quality response to O3 was not changed by interspecific competition. Lack of injury and nutritive quality response in P. pratensis harvested in September may reflect recovery from early-season O3 exposure.     

Simulation of effects of atmospheric ethylene on tree leaf shedding

This study made a preliminary assessment of the possibility that ethylene contained in polluted atmospheres affects leaf shedding of trees. The effect of ethylene dosage (ppb x h) on leaf shedding at various temperatures was approximated by using a polynomial regression. The effect of ethylene dosage on shedding of tree leaves with various sensitivities to this hydrocarbon was simulated in connection with the relationship between ethylene concentrations (10-100 ppb), dosage periods (0-50 days) and temperature (10-30 degrees C). The simulated results indicated the possibility that, for the tree group having high sensitivity, the rate of leaf shedding due to a dosage of ethylene with a concentration as low as 20 ppb, which is commonly observed in urban atmospheres, increased with temperature. On the other hand, the same concentration scarcely influenced leaf shedding in the low sensitivity group even at a temperature as high as 30 degrees C. The results for the real atmosphere determined at the Tokyo metropolitan center indicated the possibility that, for trees having high sensitivity, the rate of leaf shedding increased with rises in both monthly ethylene concentrations and air temperatures and reached a maximum of 90% in July. But in December when the concentration again reached the same value as in July while the mean monthly air temperature was 9.3 degrees C, the rate was only 10%.     

Using pollution roses to assess sulfur dioxide impacts in a township downwind of a petrochemical complex

This study used pollution roses to assess sulfur dioxide (SO₂) pollution in a township downwind of a large petrochemical complex based on data collected from a single air quality monitoring station. The pollution roses summarized hourly SO₂ concentrations at the Taishi air quality monitoring station, located approximately 7.8–13.0 km south of the No. 6 Naphtha Cracking Complex in Taiwan, according to 36 sectors of wind direction during the preoperational period (1995–1999) and two postoperational periods (2000–2004 and 2005–2009). The 99th percentile of hourly SO₂ concentrations 350? downwind from the complex increased from 28.9 ppb in the preoperational period to 86.2–324.2 ppb in the two postoperational periods. Downwind SO₂ concentrations were particularly high during 2005–2009 at wind speeds of 6–8 m/sec. Hourly SO₂ levels exceeded the U.S. Environmental Protection Agency (EPA) health-based standard of 75 ppb only in the postoperational periods, with 65 exceedances from 0–10? and 330–350? downwind directions during 2001–2009. This study concluded that pollution roses based on a single monitoring station can be used to investigate source contributions to air pollution surrounding industrial complexes, and that it is useful to combine such directional methods with analyses of how pollution varies between different wind speeds, times of day, and periods of industrial development.

Implications: The pollution roses summarize SO₂ concentrations by wind direction and to investigate source contribution to air quality. Percentile statistics can catch pollution episodes occurring in a very short time at specific wind directions and speeds. The downwind areas have already exceeded regulated 1-hr SO₂ standard since the operation of the complex.     

Effects of airborne volatile organic compounds on plants

Routine measurements of volatile organic compounds (VOCs) in air have shown that average concentrations are very much smaller than those used in laboratory experiments designed to study the effects of VOCs on plants. However, maximum hourly concentrations of some VOCs can be 100 times larger than the average, even in rural air. Experimental studies have rarely extended for longer than a few days, so there is little information on potential long-term effects of exposure to small concentrations. This review considers the available evidence for long-term effects, based on laboratory and field data. Previous reviews of the literature from Germany and the USA are cited, prior to an assessment of the effects of individual VOCs. Although hydrocarbons from vehicle exhausts have been implicated in the observed effects on roadside vegetation, the evidence suggests that it is the nitrogen oxides in the exhaust gases that are mostly responsible. There is evidence that aromatic hydrocarbons can be metabolised in plants, although the fate of the metabolites is not known. There is a large literature on the effects of ethylene, because of its role as a plant hormone. Effects have been reported in the field, in response to industrial emissions, and dose-response experiments over several weeks in laboratory studies have clearly identified the potential for effects at ambient concentrations. The main responses are morphological (e.g. epinasty), which may be reversible, and on the development of flowers and fruit. Effects on seed production may be positive or negative, depending on the exposure concentration. Chlorinated hydrocarbons have been identified as potentially harmful to vegetation, but only one long-term experiment has studied dose-response relationships. As for ethylene, the most sensitive indication of effect was on seed production, although long-term accumulation of trichloroacetic acid in tissue may also be a problem. There is little evidence of the direct effects of oxygenated hydrocarbons on plants. Plants are a significant emission source of short-chain alcohols, aldehydes and ketones. Peroxyacetyl nitrate (PAN) has a well-documented history as damaging to vegetation. There have been few long-term experimental studies despite the field evidence for damaging effects. Early studies in California have been followed by more recent data from east Asia, but there is still a dearth of information on the potential for effects of PAN and related peroxyacyl nitrates on vegetation typical of regions around tropical and sub-tropical cities where PAN pollution is increasingly important. The lack of long-term measurements, coupled with the available evidence that effects are not linearly related to 'dose' measured as the product of exposure concentration and time, means that the possibility of adverse effects of VOCs on vegetation cannot be safely rejected, particularly in urban and industrial areas. Although reproductive processes (flowering, seed production) appear to be most sensitive, there have been no experimental studies on subsequent seed viability and the consequences at the ecosystem level of changes to plant phenology. The potential for VOC metabolites to accumulate in plant tissue has been demonstrated, but any subsequent effects on herbivores and phytophagous insects have yet to be investigated.     

Studies on the progeny of rice plants grown at an unpolluted and polluted site

Oryza sativa L. cv. GR3 was grown near to a fertilizer plant and the growth of its seed progeny was evaluated at sites near to, and distant from, the fertilizer plant. The grain yield was reduced in plants grown at the polluted site, with reduced panicle length and increased sterility index. This decrease in grain yield was higher in the progeny plants than in the normal polluted plants. The polluted progeny grown at a control site showed a normal yield, but an increased sterility index. Accumulation of total sulphur and fluoride was higher in the leaves of polluted rice plants. It was evident that tolerance to air pollution was reduced in the progeny plants due to an additional dosage of sulphur and fluoride pollutants and to unfavourable climatic factors. Further, pollution effects were not carried over in progeny plants when grown in an unpolluted environment.     

Surface ozone and NOx concentrations at a high altitude Mediterranean site,Greece

Ozone was measured in six- and NO_x in five sampling periods in 1996–97, mostly during summer, at a 1070 m altitude site in northern Peloponnese. Mean values in each sampling period ranged from 43–48 ppb exceeding the European Union 24 h plant protection standard. The background ozone concentration of 43 ppb derived from the correlation of ozone with NO^′_x also exceeded the EU plant protection standard. Ozone exhibited maxima in the afternoon and minima during the night; in certain 24–48 h periods, however, the ozone concentrations remained practically constant; in these short periods air mass back trajectories indicated air masses which originated in north Africa. NO^′_x concentrations had maximum of 24 h around noon. Their mean concentrations ranged from 0.5–0.7 ppb, smaller than respective concentrations in north-central Europe.     

Ozone and increased nitrogen supply effects on the yield and nutritive quality of Trifolium subterraneum

The influence of ambient ozone (O₃) concentrations and nitrogen (N) fertilization, singly and in combination, on the growth and nutritive quality of Trifolium subterraneum was assessed. This is an important O₃-sensitive species of great pastoral value in Mediterranean areas. Plant material was enclosed in open-top chambers (OTCs). Three O₃ levels were established: Filtered air with O₃ concentrations below 15 ppb (CFA), non-filtered air with O₃ concentrations in the range of ambient levels (NFA), and non-filtered air supplemented with 40 ppb O₃ over ambient levels (NFA+). Similarly, three N levels were defined: 5, 15 and 30 kg ha⁻¹. The increase in O₃ exposure induced a reduction of the clover aerial green biomass and an increase of senescent biomass. Ozone effects were more adverse in the root system, inducing an impairment of the aerial/subterranean biomass ratio. Compared with the CFA treatment, nutritive quality of aerial biomass was 10 and 20% lower for NFA and NFA+ treatments, respectively, due to increased concentrations of acid detergent fiber, neutral detergent fiber and lignin. The latter effect appears to be related to senescence acceleration. The increment in N supplementation enhanced the increase of ADF concentrations in those plants simultaneously exposed to ambient and above-ambient O₃ concentrations, and reduced the incremental rate of foliar senescence induced by the pollutant.     

A prediction-based approach to modelling temporal and spatial variability of traffic-related air pollution in Montreal, Canada

Concentrations of traffic-related air pollution can be highly variable at the local scale and can have substantial seasonal variability. This study was designed to provide estimates of intra-urban concentrations of ambient nitrogen dioxide (NO₂) in Montreal, Canada, that would be used subsequently in health studies of chronic diseases and long-term exposures to traffic-related air pollution. We measured concentrations of NO₂ at 133 locations in Montreal with passive diffusion samplers in three seasons during 2005 and 2006. We then used land use regression, a proven statistical prediction method for describing spatial patterns of air pollution, to develop separate estimates of spatial variability across the city by regressing NO₂ against available land-use variables in each of these three periods. We also developed a “pooled” model across these sampling periods to provide an estimate of an annual average. Our modelling strategy was to develop a predictive model that maximized the model R². This strategy is different from other strategies whose goal is to identify causal relationships between predictors and concentrations of NO₂.Observed concentrations of NO₂ ranged from 2.6 ppb to 31.5 ppb, with mean values of 12.6 ppb in December 2005, 14.0 ppb in May 2006, and 8.9 ppb in August 2006. The greatest variability was observed during May. Concentrations of NO₂ were highest downtown and near major highways, and they were lowest in the western part of the city. Our pooled model explained approximately 80% of the variability in concentrations of NO₂. Although there were differences in concentrations of NO₂ between the three sampling periods, we found that the spatial variability did not vary significantly across the three sampling periods and that the pooled model was representative of mean annual spatial patterns.     

The Impact of Stratospheric Ozone on Tropospheric Air Quality

A background of ozone (O₃), principally of stratospheric origin, is present in the lower free troposphere. Typical mean O₃ levels of 50 ppb, 40 ppb, and 30 ppb are encountered here in spring, summer, and fall, respectively. Maximum hourly O₃ concentrations which are twice these mean values can be expected. Ozone from the free troposphere is routinely brought down to ground level under turbulent atmospheric conditions. Deep and rapid Intrusions of stratospheric air into the lower troposphere are associated with low-pressure troughs and occur regularly. In the mid troposphere, O₃ levels as high as 300 ppb are found within these intrusions. Observational data showing these intrusions, containing high O₃ concentrations, to directly reach ground level are currently lacking. Over the United States, an intrusion was present aloft on 8 9% of the days in 1978. The frequency, however, is somewhat reduced in summer and a northward movement is evident. During 1978, no intrusion occurred south of 30°N between June and August and none south of 40 °N in August.

The hypothesis that low levels of stratospheric O₃ produce disproportionately large amounts of O₃ in the polluted atmosphere cannot be supported from currently known chemistry but should be studied further. The experimental technique involving a ⁷Be/O₃ ratio to estimate the daily stratospheric component of ground level O₃ is unverified and considered to be inadequate for air quality applications. Estimates resulting from such a technique are considered uncertain by a factor of more than three. Specially designed aircraft studies provide the best means to determine quantitatively the impact of stratospheric O₃ on ground level air quality.     

Potential Interference Bias in Ozone Standard Compliance Monitoring

Abstract

The U.S. Environmental Protection Agency has established a federal reference method (FRM) for ozone (O₃) and allowed for designation of federal equivalent methods (FEMs). However, the ethylene‐chemiluminescence FRM for O₃ has been replaced by the UV photometric FEM by most state and local monitoring agencies because of its relative ease of operation. Accumulating evidence indicates that the FEM is prone to bias under the hot, humid, and stagnant conditions conducive to high O₃ formation. This bias may lead to overreporting hourly O₃ concentrations by as much as 20–40 ppb. Measurement bias is caused by contamination of the O₃ scrubber, a problem that is not detected by dry air calibration. An adequate wet test has not been codified, although a procedure has been proposed for agency consideration. This paper includes documentation of laboratory tests quantifying specific interferant responses, collocated ambient FRM/FEM monitoring results, and smog chamber comparisons of the FRM and FEMs with alternative scrubber designs. As the numbers of reports on monitor interferences have grown, interested parties have called for agency recognition and correction of these biases.     

Assessment of yield losses in tropical wheat using open top chambers

The present study deals with the evaluation of effects of ambient gaseous air pollution on wheat (Triticum aestivum L. var. HUW-234) growing in a suburban area situated in eastern Gangetic plain of India, using open top chambers. Eight hourly air monitoring was conducted for ambient concentrations of SO₂, NO₂ and O₃ in filtered chambers (FCs), non-filtered chambers (NFCs) and open plots (OPs). Various morphological, physiological and biochemical parameters were assessed during different developmental stages and finally yield parameters were quantified at the time of harvest.Mean concentrations of SO₂, NO₂ and O₃ were 8.4, 39.9 and 40.1 ppb, respectively during the experiment in NFCs. Concentrations of SO₂, NO₂ and O₃ reduced by 74.6%, 84.7% and 90.4%, respectively in FCs as compared to NFCs. Plants grown in FCs showed higher photosynthetic rate, stomatal conductance, chlorophyll content and Fv/Fm ratio as compared to the plants in NFCs and OPs. Lipid peroxidation, proline, total phenol and ascorbic acid contents and peroxidase activity were higher in plants grown in NFCs. There were improvements in morphological parameters of plants growing in FCs as compared to those in NFCs and OPs. Yield of plants also increased significantly in FCs as compared to those ventilated with ambient air (NFCs) or grown in OPs. During the vegetative phase, NO₂ concentrations were higher than O₃, but O₃ became dominant pollutant during the time of grain setting and filling. The study concludes that O₃ and NO₂ are the main air pollutants in the sub-urban areas causing significant yield reductions in tropical wheat plants.     

Monitoring the effects of atmospheric ethylene near polyethylene manufacturing plants with two sensitive plant species

Data of a multi-year (1977-1983) biomonitoring programme with marigold and petunia around polyethylene manufacturing plants was analysed to assess plant responses to atmospheric ethylene and to determine the area at risk for the phytotoxic effects of this pollutant. In both species, flower formation and growth were severely reduced close to the emission sources and plant performance improved with increasing distance. Plants exposed near the border of the research area had more flowers than the unexposed control while their growth was normal. Measurements of ethylene concentrations at a border site revealed that the growing season mean was 61.5 g m(-3) in 1982 and 15.6 g m(-3) in 1983. In terms of number of flowers, petunia was more sensitive than marigold and adverse effects were observed within ca. 400 m distance from the sources for marigold and within ca. 460 m for petunia. The area at risk (ca. 870 m) for ethylene-induced growth reduction was also limited to the industrial zone. Plants were more sensitive to ethylene in terms of growth reduction than in terms of inhibition of flowering. In the Netherlands, maximum permissible levels of ethylene are currently based on information from laboratory and greenhouse studies. Our results indicate that these levels are rather conservative in protecting field-grown plants against ethylene-induced injury near polyethylene manufacturing plants.     

Effects of air filtration on spring wheat grown in open-top field chambers at a rural site. II. Effects on mineral partitioning, sulphur and nitrogen metabolism and on grain quality

In 1988 the effect of ambient levels of air pollutants on the nutrients status and grain quality of spring wheat (Triticum aestivum cv. Pelican) was investigated by comparing plants grown in open-top chambers (OTC) ventilated with ambient air (NF treatments) and charcoal-filtered air (CF treatments) at a rural site (Tervuren, Belgium). Spring wheat cultivated in NF OTC showed only minor differences in the P, K, Ca, Mg, Mn and Na concentrations of the different plant parts at final harvest, as well as organic and inorganic S fractions, compared to those of the plants grown in CF air. The plants' total P content was reduced, as well as the P and K concentration of the flour. The total S concentration of the flour was increased by 4%. Effects on N concentrations and grain quality were much more pronounced. At final harvest the N concentrations of straw and flour of the NF air treated plants were much higher compared to CF air. However, the N content of the aerial biomass and the grain N yield were not significantly affected, implying a reduction of other structual compounds. Nitrogen harvest index (NHI) and the ratio of NHI over grain harvest index (GHI), indicated a significant reduction of N translocation from the above-ground biomass to the grain. Changes in the N status and partitioning of spring wheat had an effect on the baking quality of wheat flour. Several parameters that are commonly used as an indication of baking quality have been significantly increased in the NF treatment: total protein concentration, Zeleny value, dry and wet gluten concentration. A slightly increased Hagberg value indicated a reduced alpha-amylase activity. The possibility of foliar N uptake as an additional N source, especially after anthesis and implications of increased protein production instead of carbohydrate synthesis are discussed.     

Modelling of indoor exposure to nitrogen dioxide in the UK

A dynamic multi-compartment computer model has been developed to describe the physical processes determining indoor pollutant concentrations as a function of outdoor concentrations, indoor emission rates and building characteristics. The model has been parameterised for typical UK homes and workplaces and linked to a time-activity model to calculate exposures for a representative homemaker, schoolchild and office worker, with respect to NO₂. The estimates of population exposures, for selected urban and rural sites, are expressed in terms of annual means and frequency of hours in which air quality standards are exceeded. The annual mean exposures are estimated to fall within the range of 5–21 ppb for homes with no source, and 21–27 ppb for homes with gas cooking, varying across sites and population groups. The contribution of outdoor exposure to annual mean NO₂ exposure varied from 5 to 24%, that of indoor penetration of outdoor air from 17 to 86% and that of gas cooking from 0 to 78%. The frequency of exposure to 1 h mean concentrations above 150 ppb was very low, except for people cooking with gas.     

Air Pollution Control and Waste Management in a New World

Abstract

A research site for atmospheric chemistry and air pollution measurements was established at Pinnacle State Park in Addison, NY, in 1995. This paper presents an overview of the site characteristics and measurement program, as well as monthly average concentrations for many of the trace gas and aerosol pollutants over the full measurement period. Monthly averaged ozone concentrations range from values as low as 15 parts per billion (ppb) during cold-season months, to values approaching 50 ppb during some spring and summer months. Sulfur dioxide (SO₂), oxides of nitrogen (NO_x), and reactive odd nitrogen (NO_y) all show distinct seasonal variation, with summertime monthly averages as low as 1–3 ppb, and wintertime monthly averages from 6–12 ppb. The variation in carbon monoxide (CO) is much smaller, with minimums of approximately 150 ppb and maximums only rarely exceeding 250 ppb. Data for three hydrocarbon species propane, benzene, and isoprene—are presented. Propane and benzene show higher monthly averaged concentrations in the winter and lower values in the summer, with values ranging over a factor of 4–5. Isoprene, on the other hand has much higher values during the summer season, sometimes a factor of 10 or more greater than concentrations measured in the winter. Monthly averaged plots for fine particulate matter (PM_2.5) beginning in 1999 show a robust summer maximum and winter minimum, and roughly a factor of two difference between the two. An empirical measure of ozone production using the correlation of hour-averaged ozone and NO_y data illustrates relatively robust ozone production during some, but not all, summertime months over the time period. Also, an analysis of the frequency distribution of the hours of maximum ozone concentration shows a strong mid-afternoon peak, as expected, but also a prominent secondary maximum centered around midnight. The secondary peak is interpreted as ozone transported from ozone-producing areas to the west, including Buffalo, Cleveland, Pittsburgh, and the Ohio Valley. Finally, SO₂ concentrations as a function of wind direction clearly indicate maximum impacts when the winds are out of the south (Pittsburgh and Philadelphia), with a secondary peak when the winds are from the north-northeast, consistent with the locations of major SO₂ emission sources in the region.     

Revised estimates of construction activity and emissions: Effects on ozone and elemental carbon concentrations in southern California

Emissions from diesel-powered construction equipment are an important source of nitrogen oxides (NO_x) and particulate matter (PM). A new emission inventory for construction equipment emissions is developed based on surveys of diesel fuel use; the revised inventory is compared to current emission inventories. California's OFFROAD model estimates are 4.5 and 3.1 times greater, for NO_x and PM respectively, than the fuel-based estimates developed here. The most relevant uncertainties are the overall amount of construction activity/diesel fuel use, exhaust emission factors for PM and NO_x, and the spatial allocation of emissions to county level and finer spatial scales. Construction permit data were used in this study to estimate spatial distributions of emissions; the resulting distribution is well correlated with population growth. An air quality model was used to assess the impacts of revised emission estimates. Increases of up to 15 ppb in predicted peak ozone concentrations were found in southern California. Elemental carbon and fine particle mass concentrations were in better agreement with observations using revised emission estimates, whereas negative bias in predictions of ambient NO_x concentrations increased.     

Summer air quality over an artificial lake

In the summer of 1998, the air quality (indicators: CO, NO, NO₂, O₃) above the water surface of the Lake Balderey (Essen, Ruhr area, North Rhine-Westphalia, Germany), an artificial lake used for recreation purposes, was measured using the Fourier transform infrared spectroscopy (FTIR) and differential optical absorption spectroscopy (DOAS) remote measurement methods. The lake, with an area of 3 km² was created by damming the Ruhr and is surrounded by higher ground. In calm, bright weather conditions, this location results in a low-exchange situation (formation of temperature inversions, cold air dynamics) with a sustained impact on pollutant concentrations over the lake. The results of trace substance measurements (1/2 h mean values) were compared with values from comparison stations (suburban, high traffic and forest) located outside the area of the lake. In general, it was found that mean CO and NO concentrations over the lake were very low (0.3 ppm and 7.5 ppb, respectively). NO₂ values (15 ppb) were some 3.5 times higher than those recorded at the forest station and O₃ values, at 27 ppb, almost reached the same level as at the forest station (30 ppb). Mass flow densities as a function of wind direction, diurnal courses, differences between weekdays and weekends and comparisons with air quality standards are presented for the lake station.     

Effects of photochemical smog and mineral nutrition on ponderosa pine seedlings

Two-year-old seedlings of ponderosa pine (Pinus ponderosa Dougl. ex Laws) were exposed to ambient concentrations of photochemical smog (AA) and clean air (CA) during a single field season at Tanbark Flat of the San Gabriel Mountains in the Los Angeles Basin. The seedlings were grown in a perlite-vermiculite medium with full supply of nutrients (based on modified Hoagland solution); reduced to 50% supply of N; reduced to 50% supply of Mg; and reduced to 50% supply of N+Mg. No significant effects of air pollution exposures on injury development, stem growth and concentrations of plant pigments were determined. The seedlings in the AA treatment had decreased N concentration in current year needles compared with CA seedlings; however, the needle concentrations of other elements did not change. Reduction of N supply in the growing medium caused decreased N, P, Ca, K and chlorophyll a concentrations in needles. Stem growth of the seedlings with reduced N supply was significantly decreased as well. No changes in stem growth or chemical composition of plants with reduced Mg supply were noted. Reduction of supply of nutrients did not change responses of trees to the air pollution exposures.