Atmospheric Environment (v.42, #3)
Editorial board (i).
Atmospheric emissions modeling of energetic biomass alternatives using system dynamics approach by Nora Szarka; Orsolya Kakucs; Jürgen Wolfbauer; Alberto Bezama (403-414).
To simulate the quantitative effects of regional biomass alternatives for energetic purpose (BfE) on air pollutant emissions, a system dynamics model was developed and applied for the EuRegion Austrian–Hungarian cross-border area. The dynamic simulation program Vensim® was used to build an overall regional model with economic, social and environmental sectors. Within this model, the here-introduced regional air pollution sub-model (RegAir) includes the important human-made emissions of 10 pollutants resulting from all relevant source sectors within the region investigated. Emissions from activities related to biomass production, transport, conversion and final energy consumption were built in detail. After building and calibrating the RegAir model, seven quantitative test scenarios were defined and implemented into the model. Through the scenarios simulation, effects on air emissions were followed and compared over time. The results of these simulations show a significant reduction of CO2 emissions, especially in cases where fossil fuel displacement in heating devices is achieved on the largest scale. On the contrary, traditional air pollutants increase by most BfE options.The results of the RegAir model simulations of BfE alternatives over two decades provide useful quantifications of various air emissions and identify the less pollutant BfE alternatives in the dynamic context of the relevant air pollution sources of the region. After minor structural modifications and appropriate calibration, RegAir can be applied to other regions as well. However, it is stated that, to finally decide on the overall most-appropriate options at a regional level, other environmental as well as economic and social effects must be taken into consideration, being the latter the goal of the mentioned overall regional model which serves as a model frame to the RegAir tool.
Keywords: Atmospheric emissions; System dynamics; Regional modeling; Energetic biomass;
Lagrangian modelling of plume chemistry for secondary pollutants in large industrial plumes by D.R. Middleton; A.R. Jones; A.L. Redington; D.J. Thomson; R.S. Sokhi; L. Luhana; B.E.A. Fisher (415-427).
Industrial sources of nitrogen oxides range from boilers and metal furnaces to fossil fuel power stations. Current UK regulatory practice for these plumes adopts a fixed proportion of nitrogen dioxide, as a simple and conservative method of assessment. The method of Janssen is another possible approach. The aim of the present paper is to use a fundamental description of plume chemistry to investigate the sensitivity of nitrogen dioxide and ozone to changes in the background pollutants. The newly developed Met Office's NAME III Lagrangian dispersion model was used to simulate the inhomogeneous mixing of an idealised plume with background air. Concentrations of nitrogen oxides in the plume and of ozone and hydrocarbons in the background were carried on Lagrangian particles and mixed together. Titration of background ozone and formation of secondary pollutants were studied as background concentrations were varied systematically. We present a range of model results depicting the plume chemistry. Raised concentrations of nitrogen dioxide appeared on the plume edges, especially at night. Ozone was reduced in the plume region by day and by night, but in daylight, with sufficient hydrocarbons, increased ozone is formed further downwind. We compared the model results with the limiting case from the Janssen method; the limiting values for the NO2:NO x ratio were of similar magnitude. The rate of increase of the ratio to the Janssen photochemical limit depended on the atmospheric stability, as this affects the turbulent mixing in the plume. We discuss possible application of the work as an alternative to empirical regulatory approaches for managing NO2.
Keywords: Nitrogen dioxide; Ozone; Hydrocarbons; Background pollutant; Inhomogeneous mixing; Janssen;
The impact of a forced reduction in traffic volumes on urban air pollution by Yuval; Bernanda Flicstein; David M. Broday (428-440).
The Middle East military conflict of summer 2006 resulted in a few weeks in which the city of Haifa, Israel, and its environs experienced very profound variations in the commercial and personal activities. Large industrial plants continued almost normal operations but activities of small scale industry, shopping, and personal commuting were drastically reduced, leading to a dramatic decrease in the commercial and personal traffic volumes. This period of reduced activity serves as a real life experiment for assessment and demonstration of the impact that human activity, and mainly road traffic, may have on the air pollution levels in a bustling middle-sized city. The analysis is made especially sharp and reliable due to the abruptness of the beginning and the end of the reduced activity period, its length, and the stable summer meteorological conditions in the eastern Mediterranean region. The reduced traffic volumes resulted in lowered levels of NO2, hydrocarbons and particulate matter. The decrease in these pollutants’ mean concentration was significantly larger than the reduction in the mean traffic volume. Slightly higher mean O3 concentrations were observed during the reduced traffic period.
Keywords: Air pollution management; Haifa Bay area; NO x ; PM; Traffic induced air pollution;
European characterization factors for human health damage of PM10 and ozone in life cycle impact assessment by Rosalie van Zelm; Mark A.J. Huijbregts; Henri A. den Hollander; Hans A. van Jaarsveld; Ferd J. Sauter; Jaap Struijs; Harm J. van Wijnen; Dik van de Meent (441-453).
This paper presents characterization factors (CFs) for human health effects of fine particulate (PM10) and ozone in Europe for the purpose of life cycle impact assessment. The CFs express the change in disability adjusted life years (DALYs) of European inhabitants due to a change in emissions of PM10, ammonia (NH3), nitrogen oxides (NO x ), sulfur dioxide (SO2), and non-methane volatile organic compounds (NMVOCs). The CF consists of an intake factor, an effect factor, and a damage factor. The intake factor was modeled as the change in population exposure to primary and secondary aerosols, and ozone due to a change in emission of a substance. This was done with the models EUTREND (aerosols) and LOTOS–EUROS (ozone). A combined human effect and damage factor, represented by the change in DALY due to a change in population intake was derived from epidemiological-based relative risks of short-term mortality, long-term mortality, and morbidity. Primary PM10 causes 260 DALYs per kton emission, while secondary aerosol formation results in CFs between 51 and 83 DALYs per kton of precursor emitted. Applying CFs for high and low stack sources separately for PM10 and SO2 life cycle emissions can lead to a better estimation of human health damage due to these pollutants. CF related to ozone formation emissions appear to be much lower (0.04 DALY per kton, calculated based on maximum daily 8-h average ozone concentration) compared to the CF for primary and secondary PM10. When calculating CF based on 24-h average ozone concentration, NMVOC causes 0.04 DALYs per kton, while the CF for NO x causing ozone formation is negative due to reactivity of ozone with NO in areas with high NO x levels (−0.12 DALYs per kton). Total European emissions of the five priority air pollutants in year 2000 are attributed to 4.2 million DALYs for the European population, which corresponds on average to 0.25 DALYs per person over a lifetime (80 years).
Keywords: Characterization factor; Human health damage; Intake factor; Life cycle impact assessment; Ozone; PM10;
Compliance with the annual NO2 air quality standard in Athens. Required NO x levels and expected health implications by A. Chaloulakou; I. Mavroidis; I. Gavriil (454-465).
Recent risk assessment studies have shown that high outdoor NO2 levels observed in residential areas contribute to increased respiratory and cardiovascular diseases and mortality. Detailed information on present NO2 levels as well as predictions of NO2 concentrations corresponding to reduced NO x levels in urban areas are very useful to decision and policy makers in order to protect the public health. In the present paper, monitoring stations of the Athens network are initially classified into two main groups, traffic affected and urban background, using effectively a criterion based on the ratio of annual mean NO:NO2 concentrations. Two empirical methodologies are then considered and compared for assessing the effect of different NO x levels on the attainment of the annual NO2 air quality standard at urban-background locations in the Athens area. An interesting finding is that these two methodologies, one more general and one both year and site dependent, give similar results for the specific study area and can be applied alternatively based on the length of available concentration time series. The results show that in order to meet the EU annual mean NO2 objective at all the urban-background locations of the Athens area, annual NO x concentrations should be reduced to approximately 60 μg m−3, requiring NO x emission reductions of up to 30%. An analysis of the health implications of the currently observed NO2 levels is conducted, based on a dose–response relationship, and is coupled with available health-related data for the Athens area. This analysis suggests that if NO2 concentrations were reduced to the levels of the annual EU air quality standard, then a decrease of hospital admissions of up to 2.6% would be observed, depending on the levels of NO2 measured at different monitoring sites of the Athens conurbation.
Keywords: Urban air pollution; Annual NO2 concentrations; NO x reduction; Air quality standard; NO:NO2 ratio; Oxidant; Health effects; Dose–response;
A Lagrangian particle model to predict the airborne spread of foot-and-mouth disease virus by D. Mayer; J. Reiczigel; F. Rubel (466-479).
Airborne spread of bioaerosols in the boundary layer over a complex terrain is simulated using a Lagrangian particle model, and applied to modelling the airborne spread of foot-and-mouth disease (FMD) virus. Two case studies are made with study domains located in a hilly region in the northwest of the Styrian capital Graz, the second largest town in Austria. Mountainous terrain as well as inhomogeneous and time varying meteorological conditions prevent from application of so far used Gaussian dispersion models, while the proposed model can handle these realistically. In the model, trajectories of several thousands of particles are computed and the distribution of virus concentration near the ground is calculated. This allows to assess risk of infection areas with respect to animal species of interest, such as cattle, swine or sheep. Meteorological input data like wind field and other variables necessary to compute turbulence were taken from the new pre-operational version of the non-hydrostatic numerical weather prediction model LMK (Lokal-Modell-Kürzestfrist) running at the German weather service DWD (Deutscher Wetterdienst). The LMK model provides meteorological parameters with a spatial resolution of about 2.8 km. To account for the spatial resolution of 400 m used by the Lagrangian particle model, the initial wind field is interpolated upon the finer grid by a mass consistent interpolation method. Case studies depict a significant influence of local wind systems on the spread of virus. Higher virus concentrations at the upwind side of the hills and marginal concentrations in the lee are well observable, as well as canalization effects by valleys. The study demonstrates that the Lagrangian particle model is an appropriate tool for risk assessment of airborne spread of virus by taking into account the realistic orographic and meteorological conditions.
Keywords: Lagrangian particle model; Atmospheric dispersion model; Foot-and-mouth disease; Airborne spread of virus; Veterinary epidemiology; Risk assessment;
Black carbon concentrations and diesel vehicle emission factors derived from coefficient of haze measurements in California: 1967–2003 by Thomas W. Kirchstetter; Jeffery Aguiar; Shaheen Tonse; David Fairley; T. Novakov (480-491).
We have derived ambient black carbon (BC) concentrations and estimated emission factors for on-road diesel vehicles from archived coefficient of haze (COH) data that was routinely collected beginning in 1967 at 11 locations in the San Francisco Bay Area. COH values are a measure of the attenuation of light by particles collected on a white filter, and available data indicate they are proportional to BC concentrations measured using the conventional aethalometer. Monthly averaged BC concentrations are up to five times greater in winter than summer, and, consequently, so is the population's exposure to BC. The seasonal cycle in BC concentrations is similar for all Bay Area sites, most likely due to area-wide decreased pollutant dispersion during wintertime. A strong weekly cycle is also evident, with weekend concentrations significantly lower than weekday concentrations, consistent with decreased diesel traffic volume on weekends. The weekly cycle suggests that, in the Bay Area, diesel vehicle emissions are the dominant source of BC aerosol. Despite the continuous increase in diesel fuel consumption in California, annual Bay Area average BC concentrations decreased by a factor of ∼3 from the late 1960s to the early 2000s. Based on estimated annual BC concentrations, on-road diesel fuel consumption, and recent measurements of on-road diesel vehicle BC emissions, diesel BC emission factors decreased by an order of magnitude over the study period. Reductions in the BC emission factor reflect improved engine technology, emission controls and changes in diesel fuel composition. A new BC monitoring network is needed to continue tracking ambient BC trends because the network of COH monitors has been retired.
Keywords: Coefficient of haze; Black carbon; Aethalometer; Particulate matter; Diesel vehicle; Motor vehicle emissions; Air quality; Air pollution trends;
Columnar Asian dust particle properties observed by sun/sky radiometers from 2000 to 2006 in Korea by Sang-Woo Kim; Soon-Chang Yoon; Jiyoung Kim (492-504).
Multi-year AERONET sun/sky radiometer data (2000–2006) at Gosan and Anmyon in Korea were analyzed to characterize the optical, radiative, and physical properties of Asian dust particles. Approximately, 80% of the dust storms were reported in March and April, and about 10–15% of the Asian dust events were observed during the wintertime. Similarities in the aerosol optical properties during the spring Asian dust period (SPR-AD) were found between the Gosan and Anmyon sites. The aerosol optical depth (Ångström exponent) during SPR-AD was about 40–44% higher (39–56% lower) than the optical depths reported during the spring non-Asian dust period (SPR-NAD). There was no significant difference in single scattering albedo between SPR-AD and SPR-NAD. At the Gosan and Anmyon sites, approximately 22% (29%) and 16% (16%) of direct and almucantar (the second value in parentheses) measurement data during SPR-NAD, respectively, were classified as SPR-NAD Coarse case (SPR-NAD-C), which indicates that the Asian dust storms were elevated and thus were not observed at the surface station. The aerosol properties between SPR-AD and SPR-NAD-C are almost identical. The AOD of SPR-AD is similar to that of the non-Asian dust period in May and June (MJ-NAD). However, the Ångström exponent is about two times lower than that of MJ-NAD. Aerosol volume size distributions illustrate clearly that the coarse-mode particles are dominant during SPR-AD, but that the accumulation-mode particles dominate during MJ-NAD. The largest aerosol radiative forcing and forcing efficiency were apparent during SPR-AD and SPR-NAD-C.
Keywords: Sun/sky radiometer; Asian dust; Aerosol optical depth; Gosan; Anmyon;
Concentrations and determinants of gaseous aldehydes in 162 homes in Strasbourg (France) by C. Marchand; S. Le Calvé; Ph. Mirabel; N. Glasser; A. Casset; N. Schneider; F. de Blay (505-516).
Aldehydes concentrations were measured in 162 homes in the Strasbourg area (East of France) in the context of a case/control study pairing asthmatic and non-asthmatic people. The surveyed people have completed a questionnaire aiming to characterize the indoor homes and the people life practices. Gaseous aldehyde levels were quantified by a conventional DNHP-derivatization method followed by HPLC/UV.Formaldehyde, acetaldehyde and hexanal were the main encountered aldehydes with mean concentrations of 32.2±14.6, 14.3±9.7 and 8.6±8.1 μg m−3, respectively, while propionaldehyde and benzaldehyde concentrations were usually <3 μg m−3. The aldehydes concentrations simultaneously measured in both bedroom and living room were not significantly different except for formaldehyde and were correlated between them meaning that indoor air was quite homogenous in homes.Combination of information collected in our questionnaires and statistical analysis was used to investigate indoor aldehydes determinants. Even if formaldehyde sources are theoretically well identified, they are multiple so that it was difficult to determine the main parameters influencing its concentrations in domestic environment. Higher hexanal concentrations were related to new coatings such as painting, wallpapers and laminate floorings. Hexanal concentration decreased with both coating and furniture ages so that this compound may be considered as a tracer of these emissions.
Keywords: Aldehyde; Formaldehyde; Determinants; Indoor; Atmosphere; Home;
On the interaction between glyceraldehyde-3-phosphate dehydrogenase and airborne particles: Evidence for electrophilic species by Masaru Shinyashiki; Chester E. Rodriguez; Emma W. Di Stefano; Constantinos Sioutas; Ralph J. Delfino; Yoshito Kumagai; John R. Froines; Arthur K. Cho (517-529).
Many of the adverse health effects of airborne particulate matter (PM) have been attributed to the chemical properties of some of the large number of chemical species present in PM. Some PM component chemicals are capable of generating reactive oxygen species and eliciting a state of oxidative stress. In addition, however, PM can contain chemical species that elicit their effects through covalent bond formation with nucleophilic functions in the cell. In this manuscript, we report the presence of constituents with electrophilic properties in ambient and diesel exhaust particles, demonstrated by their ability to inhibit the thiol enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GAPDH is irreversibly inactivated by electrophiles under anaerobic conditions by covalent bond formation. This inactivation can be blocked by the prior addition of a high concentration of dithiothreitol (DTT) as an alternate nucleophile. Addition of DTT after the reaction between the electrophile and GAPDH, however, does not reverse the inactivation. This property has been utilized to develop a procedure that provides a quantitative measure of electrophiles present in samples of ambient particles collected in the Los Angeles Basin and in diesel exhaust particles. The toxicity of electrophiles is the result of irreversible changes in biological molecules; recovery is dependent on resynthesis. If the resynthesis is slow, the irreversible effects can be cumulative and manifest themselves after chronic exposure to low levels of electrophiles.
Keywords: Electrophile; Glyceraldehyde-3-phosphate dehydrogenase; Airborne particulate matter; Diesel exhaust particles; Ultrafine particles;
Improving correlations between MODIS aerosol optical thickness and ground-based PM2.5 observations through 3D spatial analyses by Keith D. Hutchison; Shazia J. Faruqui; Solar Smith (530-543).
The Center for Space Research (CSR) continues to focus on developing methods to improve correlations between satellite-based aerosol optical thickness (AOT) values and ground-based, air pollution observations made at continuous ambient monitoring sites (CAMS) operated by the Texas commission on environmental quality (TCEQ). Strong correlations and improved understanding of the relationships between satellite and ground observations are needed to formulate reliable real-time predictions of air quality using data accessed from the moderate resolution imaging spectroradiometer (MODIS) at the CSR direct-broadcast ground station. In this paper, improvements in these correlations are demonstrated first as a result of the evolution in the MODIS retrieval algorithms. Further improvement is then shown using procedures that compensate for differences in horizontal spatial scales between the nominal 10-km MODIS AOT products and CAMS point measurements. Finally, airborne light detection and ranging (lidar) observations, collected during the Texas Air Quality Study of 2000, are used to examine aerosol profile concentrations, which may vary greatly between aerosol classes as a result of the sources, chemical composition, and meteorological conditions that govern transport processes. Further improvement in correlations is demonstrated with this limited dataset using insights into aerosol profile information inferred from the vertical motion vectors in a trajectory-based forecast model. Analyses are ongoing to verify these procedures on a variety of aerosol classes using data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (Calipso) lidar.
Keywords: MODIS; Air quality; Particulate matter; Aerosol optical thickness;
Study of the effects of environmental parameters on the gas/particle partitioning of current-use pesticides in urban air by Nathalie Sauret; Henri Wortham; Jean-Philippe Putaud; Philippe Mirabel (544-553).
A filter-XAD-2 resin plug high-volume air sampler was used to collect particulate (P) and gaseous (G) phases of seven pesticides (atrazine, terbuthylazine, alachlor, metolachlor, cymoxanil, diflufenicanil, and fenoxaprop-p-ethyl) and two metabolites (de-ethylatrazine (DEA) and de-ethylterbuthylazine (DET)) in downtown Strasbourg (France). Most of the molecules listed above were found to be associated only with particulate aerosols and only four of them were detected regularly in both atmospheric phases (particulate and gaseous). The results presented in this work showed that models developed previously to describe the gas/particle (G/P) partitioning did not work for currently used pesticides. A new partition equation (K org, m3 ng−1) was defined for the pesticides under study using environmental parameters such as temperature, relative humidity, and organic carbon content of atmospheric aerosols.
Keywords: Pesticide; Semi-volatile organic compounds; Gas/particle partitioning; Particulate matter; Urban air;
Regional differences in gas–particle partitioning and deposition of semivolatile organic compounds on a global scale by Christian W. Götz; Martin Scheringer; Matthew MacLeod; Fabio Wegmann; Konrad Hungerbühler (554-567).
Variability in gas–particle partitioning of semivolatile organic compounds (SOCs) and related atmospheric processes (particle-associated deposition, rain washout and degradation) are investigated on a global scale. Two different sorption approaches (one using the octanol-air partition coefficient, K OA, and one based on poly-parameter linear free energy relationships, ppLFER) and two different atmospheric box models (unit-world and highly spatially and temporally resolved) are applied. In the unit-world model, the overall deposition and atmospheric fate of SOCs calculated with the K OA-based sorption approach are similar to the ones calculated with the ppLFER approach. Rain washout dominates the atmospheric removal of polar chemicals in the unit-world model while non-polar chemicals are removed mainly through degradation or particle-associated deposition. In contrast, big differences and a high sensitivity to the selected sorption approach are found in the spatially and temporally resolved model. The highly resolved geographic variability cannot be represented using the K OA-based approach if aerosol components other than OM are of importance for sorption. In particular, aerosols in dry regions (desert) and regions with low OM aerosols (arctic, some oceanic regions) are more appropriately described by the ppLFER approach. With the ppLFER approach, good agreement between modeled deposition fluxes and measurement data are found for higher chlorinated PCBs and TCDD/Fs. In general, we recommend the ppLFER approach for highly resolved environmental fate models.
Keywords: Atmospheric deposition; Gas–particle partitioning; Semivolatile organic compounds; POPs; Remote sensing; GCM;
Using mass spectral source signatures to apportion exhaust particles from gasoline and diesel powered vehicles in a freeway study using UF-ATOFMS by Stephen M. Toner; Laura G. Shields; David A. Sodeman; Kimberly A. Prather (568-581).
Single particle mass spectrometry techniques such as aerosol time-of-flight mass spectrometry (ATOFMS) offer a unique approach for on-line source apportionment of ambient aerosols. Source signatures, or mass spectral “fingerprints”, have been obtained using ATOFMS from a variety of sources with an emphasis placed on distinguishing between emissions from different types of vehicles. In this study, the signatures from previous source tests of diesel powered heavy duty diesel vehicles (HDDV) and gasoline powered light duty vehicles (LDV) are matched to particle spectra acquired during a freeway-side study performed over a month in southern California to source apportion the particles. Using a relatively high ART-2a matching (vigilance) factor of 0.85, particle mass spectral signatures from the vehicle source studies matched 83% of the freshly emitted particles detected alongside the freeway. The particle contributions alongside the freeway in the ultrafine and accumulation size range (aerodynamic diameter=50–300 nm) were apportioned to 32% LDV, 51% HDDV, and 17% from other sources. This paper discusses the apportionment process used and the methods used for validation with peripheral instrumentation.
Keywords: Aerosol; Source apportionment; Diesel; Gasoline; ATOFMS; Single particle mass spectrometry;
Assessment of small gaseous impurities in atmosphere of arid and semi-arid territories of Mongolia by G.S. Zhamsueva; A.S. Zayakhanov; V.V. Tsydypov; A.A. Ayurzhanaev; D. Azzaya; D. Oyunchimeg (582-587).
Round-the-clock continuous synchronous measurements of concentrations of surface ozone (O3), oxides of nitrogen (NO x ), carbon dioxide (CO2), meteorological, turbulent and radiating characteristics of atmosphere are presented.Measurements were observed by means of the automated operative system of registration and statistical processing of measurements during joint Russian–Mongolian scientific expedition in arid (desert Gobi) and semi-arid territories of Mongolia in the summers 2005–2006.High concentrations of O3, NO2 appeared during of all periods of supervision in desert Gobi. The observed diurnal variations of hourly averaged concentrations of surface ozone have a minimum equal 55 μg m−3 in the morning and a maximum equal 133 μg m−3 in day-time.The correlations between concentrations of small gaseous impurities in the atmosphere and meteorological and turbulence characteristics are analyzed.Air pollution concentrations observed in arid and semi-arid territories of Mongolia are compared.
Keywords: Small gaseous impurities; Atmosphere; Turbulence characteristics; Desert Gobi;
Arabitol and mannitol as tracers for the quantification of airborne fungal spores by Heidi Bauer; Magda Claeys; Reinhilde Vermeylen; Elisabeth Schueller; Gert Weinke; Anna Berger; Hans Puxbaum (588-593).
Fungal spores constitute a sizeable fraction of coarse organic carbon (OC) in the atmospheric aerosol. In order to avoid tedious spore count methods, tracers for quantifying the spore-OC in atmospheric aerosol are sought. Arabitol and mannitol have been proposed as such tracers, since no other emission sources for these compounds have been reported. By parallel investigations of spore counts and tracer determinations from PM10 filter samples we could derive quantitative relationships between the amounts of tracer compounds and the numbers of spores in the atmosphere for different sites in the area of Vienna. We obtained over all average relationships of 1.2 pg arabitol spore−1, with a range of 0.8–1.8, and 1.7 pg mannitol spore−1, with a range of 1.2–2.4, with a clear site dependence. Thus, using these conversion factors from spore counts to spore-OC and spore-mass, along with analytical data for arabitol or mannitol in filter samples, the contribution of fungal spores to the OC and to the mass balance of atmospheric aerosol particles can be estimated.
Keywords: Fungal spores; Organic carbon; Biogenic aerosol; PM10; Sugar alcohols;
Purification characteristics of pothos for airborne chemicals in growing conditions and its evaluation by Ayako Sawada; Takashi Oyabu (594-602).
Plants have a purification capability to various kinds of airborne chemicals. The capability largely depends on the growing conditions of the plant. In this study, the capabilities of the plants growing in the following three conditions were examined: (a) put the subjective plant in a bowl of tap water, (b) put the one in a pot of growing water for over 1 year and (c) in the pot-soil. The room temperature and light intensity were changed in the experiments. As a result, it became obvious that the capability to formaldehyde varied in some degree according to room temperature. The capability decreased linearly in 12–25 °C in the case of (a), it did not change largely in the case of (b) and it indicated maximum value at 21 °C in the case of (c). The temperature belonged to optimal growth range of the plant. The capability-order is as follows: (a)<(b)<(c). The capability increased as the light intensity increased in each growth-condition. The capabilities to acetone, toluene and xylene were also examined. It became obvious that the capability became lower as the molecular weight of the chemical became larger.
Keywords: Air pollution; Air purification; Foliage plant; Growth-condition;
New Directions: Why are PM10 concentrations in Europe not falling? by Roy M. Harrison; John Stedman; Dick Derwent (603-606).