Photochemical Ozone Formation Research Articles

Life cycle assessment of recycling options for polylactic acid

This paper presents an attributional life cycle assessment for different recycling technologies for post-industrial and post-consumer polylactic acid (PLA) waste in Germany. The study investigates mechanical recycling of post-industrial and post-consumer PLA waste as well as solvent based recycling and chemical recycling of post-consumer PLA waste. Recycling of PLA waste is exclusively compared to thermal treatment since a comparison of the different recycling options is not possible due to different qualities of the waste streams and of the products. The life cycle impact results show environmental benefits of all recycling technologies. Environmental benefits are achieved by replacing virgin PLA with PLA recyclates. The substitution of virgin PLA by recyclates leads to higher savings of greenhouse gas emissions compared to incineration. Depending on the recycling technology, savings are 0.3–1.2 times higher. The lower global warming impact goes along with higher savings in primary energy demand and less fossil resource depletion. Apart from benefits related to global warming impact and energy, the comparison between thermal treatment and the recycling shows benefits in the category agricultural land occupation since biomass cultivation is avoided. Further environmental benefits are achieved in the impact categories photochemical ozone formation, terrestrial and aquatic eutrophication, acidification, and particulate matter due to avoided biomass cultivation, harvesting, and transportation. The latter three impacts are mainly influenced by agricultural activities and transportation, whereas eutrophication is driven by fertilization. The results demonstrate that recycling of PLA products can contribute to a better environmental performance of PLA products in their life cycle.

BASF unveils strategy to reduce carbon intensity

For successful implementation of sustainability in industry robust assessments of products and processes are necessary that quantify environmental aspects under consideration of costs. The sustainability needs of companies vary greatly according to region, sector and stakeholder. BASF has developed a toolbox for eco-efficiency assessments that addresses the broad range of in-house and external needs, allowing flexibility while ensuring that relevant and sufficient environmental impact is covered to support decision-making based on quantified sustainability assessments. The toolbox is based on standard practices for life cycle assessment to support strategic decisions, product development and marketing. Environmental impact assessment follows ISO 14040 and 14044. Impacts are aggregated to an overall environmental impact. Life cycle costs are similarly determined and may be combined with environmental impact to an overall Eco-Efficiency Portfolio and Eco-Efficiency Index. The relevance check ensures inclusion of main impact categories and coverage of sufficient environmental impacts. A peer-reviewed case study on the treatment of flowback from fracturing operations demonstrates the applicability of the Eco-Efficiency Analysis. Deposition of flowback in existing hydrocarbon-containing reservoirs was compared with treatment in preparation for disposal to a municipal waste water treatment plant. The Reservoir option is more eco-efficient both at low and high flowback volumes. Disadvantages of the waste water treatment option include the greenhouse gas emissions associated with the high energy needed for the removal of dissolved solids from the flowback. The relevance check shows that climate change is the dominant environmental impact, but photochemical ozone formation, acidification, freshwater eutrophication, human toxicity and resource depletion (mineral & fossil) are significant as well.

Combining material flow analysis with life cycle assessment to identify environmental hotspots of urban consumption

Understanding the global environmental impacts of local consumption is an area of growing interest among policymakers and consumers. By knowing what products comprise urban consumption “hotspots,” municipalities and consumers alike could take deliberate actions to target and discourage consumption of high-impact products. In this paper, a new method for identifying environmental hotspots of consumption is presented. The main methodological advances are the following: i) material flow analysis of urban areas and life cycle assessment are combined; ii) a 16-year time-series of urban consumption data is used for selection of the most suitable representative products and for trend analysis; iii) representative products are selected systematically from consumption data of 1000 product types; iv) representative products are scaled up to represent consumption of the product groups; v) hotspots are identified by simultaneously evaluating six environmental impacts - acidification, climate change, eutrophication (marine and freshwater), photochemical ozone formation, and resource use; vi) for the case study, hotspots are connected to the city's profiles. The method was applied to the Swedish cities Stockholm, Gothenburg and Malmo and to Sweden in total. Electronics is a hotspot for all the studied areas and all the studied impacts and should be a prioritized product group for action. Fuel is a hotspot shared by all the areas while vehicles is a hotspot in Gothenburg. Meat is a nationwide hotspot, but not for the cities investigated. Gothenburg and Stockholm could collaborate to find effective measures for their common hotspot machinery. Thus, the method can be used to identify hotspots and find which product types could be part of national versus local programs.

Life cycle assessment of forest-based biomass for bioenergy: A case study in British Columbia, Canada

Large quantities of residual forest-based biomass, including harvesting and sawmill residues, are available in British Columbia, Canada. They can be used to generate bioenergy. Currently, harvesting residues are burned to reduce fire hazard, and private and remote sawmills’ residues are either burned or landfilled. While previous studies assessed the impact of bioenergy production from residual forest-based biomass on global warming, this life cycle assessment includes a comprehensive set of ten impact categories. Adopting a case study in a region in British Columbia, a life cycle model is applied to three locations considering four combustion and gasification technologies with different capacities (0.5 MW, 2 MW, 3 MW and 5 MW) and product outputs (electricity and/or heat). Most bioenergy supply chain scenarios showed improved environmental performance due to avoided uncontrolled combustion of residues and avoided fossil fuel combustion, particularly in the categories of acidification (+1% to -71%), eutrophication (-2% to -85%), fossil resource depletion (-2% to -84%), respiratory effects (0% to -96%), and photochemical ozone formation (+3% to -59%). Benefits were larger at locations dependent on fossil energy compared to locations dependent on hydropower. In contrast, ecotoxicity values increased in most scenarios (+460% to -11%), due to wood ash disposal. Results confirmed conversion efficiency and wood ash disposal as influencing factors in bioenergy supply chains for the investigated region, but showed a minor influence of the feedstock procurement distance. Moreover, the results emphasized the high contribution of uncontrolled burnings to the overall environmental impact of the forest biomass supply chains.

Environmental Assessment of the Life Cycle of Bovine Compound Feeds from a Feed Milling Plant in a Large Commercial Farm in Wielkopolska Region, Poland

In recent years, the importance of environmental threats associated with intensive livestock production has been emphasized. Compound feeds make up a part of the animal production chain. A complete assessment of the animal production system with regard to environmental criteria is therefore impossible without considering the environmental consequences of feed production. The goal of this research is to fill the gap in an environmental assessment of production processes of compound feeds in Poland. The study presents an assessment of production impacts of bovine compound feeds according to Life Cycle Analysis (LCA) methodology. The data for analysis were based on the set of information obtained from the feed milling plant located in a commercial agricultural enterprise in the Wielkopolska region in the years 2015-2016. An inventory table of inputs was prepared in relation to the functional unit of 1 ton of compound feeds and two phases of production processes, i.e. upstream and core. For average compound feed, the impact category indicators for the global warming potential, acidification, eutrophication, photochemical ozone formation, consumption of mineral resources, fossil fuel resources and the emission of the respirable particles were respectively: 605.9 kg CO2 eq, 8.73 kg SO2 eq, 3.32 kg PO4 eq, 0.73 kg ethylene eq, 3.4x10-3 kg antimony eq, 5141.1 MJ and 2.25 kg PM2.5 eq. The upstream phase had the greatest effect on investigated impacts, while the core processes phase had a relatively low impact on environmental threats. It is recommended to broaden the scope of the research for a larger group of feed milling plants with more complex manufacturing processes, with a more branched supply structure and a wide range of compound feeds for different animal types. The obtained data can be a valuable source base in prospective analyses of the life cycle of various animal products in Poland.

Global environmental impacts: data sources and methodological choices for calculating normalization factors for LCA

PurposeCharacterizing environmental impacts at the global scale is crucial to define references against which compare the environmental profile of products and systems. Within this study, global emissions and resource uses have been collected and characterized for the following impact categories: climate change, ozone depletion, human toxicity (cancer and non-cancer), ecotoxicity, particulate matter, ionizing radiation, photochemical ozone formation, acidification, eutrophication (terrestrial, marine, and freshwater), land use, water use, and resource use. The results can be used as normalization factors (NFs) in the context of the life cycle assessment (LCA).Material and methodsThe global NFs are built on an extensive collection of data on emissions and resources extracted at a global scale in 2010, gathering different sources and comparing them. A hierarchical approach was applied to the selection of data sources. Extrapolations, mainly temporal data-gap filling, were applied for complementing the inventories for missing data. In order to calculate NFs, the inventory was characterized by using the International Reference Life Cycle Data System (ILCD) midpoint indicators and the EU Environmental Footprint (EF) set, which includes recently released models.Results and discussionThe resulting global NFs (ILCD and EF) were reported and discussed for each impact category. Coverage completeness and robustness of both the underpinning inventories and impact assessment models were used to define the level of uncertainty in the calculations. Based on the contribution analysis of the main elementary flows, it resulted that only few elementary flows drive the overall impact for most of the impact categories. Moreover, the ratio between the NFs at EU27 in 2010 and global level showed that Europe generally covers less than 10% of the global impact.Conclusion and outlookThe quantification of the current levels of environmental pressures entails critical aspects, as it consists of accounting of emissions and resources, relying on data often incomplete or based on modeling. Despite the attempts made for increasing NFs coverage and robustness, the calculation in the present study highlights the need of further efforts aiming at overcoming the uncertainties and the limitations identified both at the inventory (i.e., difficulty in retrieving complete and recent data) and characterization levels (e.g., consistency between inventory and impact assessment regarding spatialization, system boundaries). Most importantly, any assessment based on the use of NFs should be carefully discussed and interpreted in light of the limitations discussed in this paper.

BASF adopts new strategy to accelerate growth

For successful implementation of sustainability in industry robust assessments of products and processes are necessary that quantify environmental aspects under consideration of costs. The sustainability needs of companies vary greatly according to region, sector and stakeholder. BASF has developed a toolbox for eco-efficiency assessments that addresses the broad range of in-house and external needs, allowing flexibility while ensuring that relevant and sufficient environmental impact is covered to support decision-making based on quantified sustainability assessments. The toolbox is based on standard practices for life cycle assessment to support strategic decisions, product development and marketing. Environmental impact assessment follows ISO 14040 and 14044. Impacts are aggregated to an overall environmental impact. Life cycle costs are similarly determined and may be combined with environmental impact to an overall Eco-Efficiency Portfolio and Eco-Efficiency Index. The relevance check ensures inclusion of main impact categories and coverage of sufficient environmental impacts. A peer-reviewed case study on the treatment of flowback from fracturing operations demonstrates the applicability of the Eco-Efficiency Analysis. Deposition of flowback in existing hydrocarbon-containing reservoirs was compared with treatment in preparation for disposal to a municipal waste water treatment plant. The Reservoir option is more eco-efficient both at low and high flowback volumes. Disadvantages of the waste water treatment option include the greenhouse gas emissions associated with the high energy needed for the removal of dissolved solids from the flowback. The relevance check shows that climate change is the dominant environmental impact, but photochemical ozone formation, acidification, freshwater eutrophication, human toxicity and resource depletion (mineral & fossil) are significant as well.

Life cycle externalities versus external costs: The case of inland freight transport in Belgium

This paper proposes a case study on Belgium in which externalities and external costs of inland freight transport modes in Belgium are compared for the year 2012. The well-known Life Cycle Assessment methodology is used to identify the updated specific Belgian externalities related to three categories of negative impacts: climate change, photochemical ozone formation and particulate matter formation. The obtained values of externalities are then compared to the related external cost values. The objective is to determine if these two tools can be used interchangeably. We find that road transport has the maximum impact for every environmental impact indicator, with rail freight transport presenting the minimum one. We identify that each category of negative impact on the environment does not represent the same percentage of global externalities and external costs. In the analysis of the environmental impact per mode, it is observed that, when external costs are considered instead of externalities, the impact of road transport is slightly increased compared to both impacts of rail and inland waterways. Using externalities and average external costs interchangeably for estimating the impact of specific transport categories on the environment may thus lead to different results and different related policies.

Implementation of the Product Environmental Footprint Category Rules for dairy products: An approach to assess nitrogen emissions in a mass balanced dairy farm system

Following the Single Market for Green Products, the European Commission released the Product Environmental Footprint Category Rules for Dairy Products (PEFCR-D). According to the PEFCR-D, nitrogen (N) emissions must be calculated as stated by The Intergovernmental Panel on Climate Change (IPCC) and the European Environmental Agency (EMEP/EEA) methods. However, since the IPCC method and the EMEP/EEA method follow different N flows, the estimated N emissions differ at common farm stages resulting in incompatibilities in the reported PEFCR-D emissions from a mass balance perspective. This work proposes a comprehensive approach to calculate N emissions to satisfy the PEFCR-D guideline in a N balanced farm system. The proposed approach coordinates and balances the N flows at each stage in order to estimate the N emissions from the dairy system. In this regard, emissions such as N2O, NH3, NOx, N2 and NO3− are estimated following the IPCC and EMEP/EEA methods from a single N flow in the system. The N losses in the whole dairy farm are estimated to increase 4.41% as a result of the implementing the PEFCR-D in a N balanced system instead of a non-balanced one. Consequently, an increase in environmental impacts of the farm such as Global Warming Potential (6.68%), Marine Eutrophication (4.91%) and Terrestrial Eutrophication (4.26%) were also measured. Moreover, the proposed approach to implement the PEFCR-D enabled the redistribution of emissions between farm stages; particularly relocating N emissions and environmental impacts between manure management and application. This resulted in a decrement on the manure management stage environmental impacts such as Global Warming (−41.88%) and Photochemical Ozone formation (−25.49%). On the other hand, at application stage, increments in Global Warming (26.94%), Marine Eutrophication (8.48%) and Terrestrial Eutrophication (7.52%) were evidenced when contrasting the outcomes between the non-balanced and balanced PEFCR-D calculation approach.

Life cycle analysis of copper-gold-lead-silver-zinc beneficiation process

Gold, silver, lead, zinc, and copper are valuable non-ferrous metals that paved the way for modern civilisation. However, the environmental impacts from their beneficiation stage was always overlooked. This paper analysed the life cycle environmental impacts from the beneficiation process of gold-silver-lead-zinc-copper combined production. The analysis is conducted by utilising the SimaPro software version 8.5. The life cycle assessment methodologies followed are the International Reference Life Cycle Data System (ILCD) method, the IMPACT 2002+ method, and the Cumulative Energy Demand Method (CED). The most significant impact categories are ecotoxicity, climate change, human toxicity, eutrophication, acidification, and ozone depletion among nearly 15 impact categories which are assessed in this study. The analysis results from the ILCD method indicate that there is a noteworthy impact on ionising radiation caused by the beneficiation process. Out of the five metals considered, gold and silver beneficiation impacts the most while lead‑zinc beneficiation impacts the least. Gold beneficiation has most impacts on the category of climate change and ecosystems. Other major impact categories are ionising radiation, terrestrial eutrophication, photochemical ozone formation, human toxicity, and acidification. The IMPACT 2002+ method shows the overall impact is on ecosystem quality and human health from this combined beneficiation process, dominantly from gold‑silver beneficiation. The life-cycle inventory results show that the blasting process and the amount of electricity consumption in the beneficiation process contribute to cause significant amount of environmental impacts. The comparative impact results are presented and discussed in detail in this paper. Sensitivity analyses are presented based on various electricity grid-mix scenarios and energy-mix scenarios, and the results suggest that electricity grid mix has a dominant effect over the fossil-fuel mix. This paper also highlights the potential steps which could cut down the environmental effects by integrating renewable-energy technologies.

Uncertainty analysis in the life cycle assessment of cassava ethanol in China

In the context of China's severe energy and environmental problems, as an alternative vehicle fuel bioethanol is a promising choice because its theoretically renewable and carbon neutral. To guarantee grain security, China is developing non-grain fuel ethanol. Based on a life cycle assessment (LCA), this paper assesses the uncertainty of energy efficiency and environmental performance in the development of cassava ethanol of 1.5-generation bioethanol whose raw materials are non-staple crops. The results show that cassava ethanol is a good alternative vehicle fuel from the view of energy efficiency. From an environment perspective, global warming potential and photochemical ozone formation potential of cassava ethanol are better than gasoline, but acidification potential and respiratory inorganics inferior. The Monte Carlo simulation reveals cassava ethanol is feasible compared with gasoline in the case of uncertain variables. Among these uncertain variables, cassava yield, nitrogen fertilizer use, and steam use are the most important variables for energy efficiency and environmental performance of cassava ethanol. Furthermore, this study calculates the potentials for energy savings and emissions reduction with improving key aspects, and gives the suggestions of enhancing the performance of key indicators to promote the development of bioethanol vehicle fuel.

Replacement of energy crops with bio-waste in existing anaerobic digestion plants: An energetic and environmental analysis

The energetic and environmental consequences of replacing energy crops (ECr) with bio-waste were analyzed by comparing two different scenarios. In the base scenario about 17,500 Mg/year of ECr and about 30,000 Mg/year of bio-waste were processed separately in an existing anaerobic digestion (AD) plant and composting plant, respectively. In the modified scenario the whole amount of bio-waste was used to replace the ECr as feedstock in the existing AD facility. The net amount of electrical energy recovered went from about 6700 MWh/year for the base scenario to about 9100 MWh/year for the modified one. From the environmental point of view the modified scenario was able to decrease both global warming and photochemical ozone formation potentials, whereas the base scenario had lower fresh water eutrophication potential and was able to avoid the consumption of resources. Both endpoint impact categories, human health and ecosystem quality, indicated that the modified scenario performed better than the base scenario. The uncertainty analysis confirmed qualitatively the results achieved.

Life Cycle Assessment of Typical Rubber-Plastic Sponge Production in China

As a kind of high-grade flexible insulation and energy-saving material, rubber-plastic sponge insulation material is produced by taking butadiene-acrylonitrile rubber and polyvinyl chloride as main materials, together with auxiliary materials such as fire retardant, plasticizer, foaming agent and filler, through production processes as weighing stock, pre-smelting, mixing, extrusion, foaming and cutting and packaging. By taking 1m3 rubber-plastic sponge as the functional unit, this paper quantitatively obtains that the impact of the product on primary energy demand, greenhouse effect, acidification potential, photochemical ozone formation potential and respirable inorganics is 2,100MJ/m3, 74.9kg CO2 equivalent/m3, 0.356kg SO2 equivalent/m3, 0.244kg NMVOC/m3 and 0.0642kg PM2.5 equivalent/m3 respectively. This paper provides reference for enterprise's cleaner production and consumer's green material selection by making life cycle assessment for rubber-plastic insulation material, quantifying the environmental load of the product, identifying the environment hot spots in product life cycle and illustrating the environment compatibility of product.

Life Cycle Assessment of Typical Glass Wool Production in China

Glass wool is the roll felt product produced by melting and fiberizing glass and then adding adhesive for curing processing. It is well-shaped, thermally insulated and corrosion resistant and has low volume density, low thermal conductivity, good acoustic absorptivity and stable chemical properties. By taking 1t glass wool as the functional unit, this paper quantitatively obtains that the impact of the product on primary energy demand, greenhouse effect, acidification potential, photochemical ozone formation potential and respirable inorganics is 1.12×105MJ/t, 8×103kg CO2 equivalent/t, 84.1kg SO2 equivalent/t, 3.21kg NMVOC/t and 15.5kg PM2.5 equivalent/t respectively. This paper provides reference for enterprise's cleaner production and consumer's green material selection by making life cycle assessment for glass wool insulation material, quantifying the environmental load of glass wool product, identifying the environment hot spots in product life cycle and illustrating the environment compatibility of product.

Environmental Impact of End-of-Life Tires: Life Cycle Assessment Comparison of Three Scenarios from a Case Study in Valle Del Cauca, Colombia

Life Cycle Assessment methodology has been applied to estimate diverse environmental impacts of different usage alternatives for worn-out tires at the end of their useful life in a case study at the Department of Valle del Cauca, Colombia. Different real scenarios were compared, which allowed for the assessment of the best environmental option for the management of worn-out tires. A method developed in the Institute of Environmental Sciences at University of Leiden, better known as CML-2001, was used to calculate the environmental impact indicators. The results show that the incineration of whole tires in cement plants, and the activities of grinding and floor manufacturing from granulated rubber, exhibited the best indicators, especially in terms of environmental load avoidance through the recovery of materials. Finally, the categories of depletion of the ozone layer, acidification, global warming potential, depletion of abiotic resources, and photochemical ozone formation revealed that the strongest environmental impacts are associated with retreading and the production of multipart asphalt. This is due to the use of synthetic rubber in the former alternative, and of liquid asphalt, gravel, and diesel consumption in the latter.

A WRF-Chem model study of the impact of VOCs emission of a huge petro-chemical industrial zone on the summertime ozone in Beijing, China

In China, petro-chemical manufacturing plants generally gather in the particular industrial zone defined as PIZ in some cities, and distinctly influence the air quality of these cities for their massive VOCs emissions. This study aims to quantify the local and regional impacts of PIZ VOCs emission and its relevant reduction policy on the surface ozone based on WRF-Chem model, through the case study of Beijing. Firstly, the model simulation under the actual precursors’ emissions over Beijing region for July 2010 is conducted and evaluated, which meteorological and chemical predictions both within the thresholds for satisfactory model performance. Then, according to simulated H2O2/HNO3 ratio, the nature of photochemical ozone formation over Beijing is decided, the VOCs-sensitive regime over the urban areas, NOx-sensitive regime over the northern and western rural areas, and both VOCs and NOx-mixed sensitive regime over the southern and eastern rural areas. Finally, a 30% VOCs reduction scenario (RS) and a 100% VOCs reduction scenario (ZS) for Beijing PIZ are additional simulated by WRF-Chem. The sensitivity simulations imply that the current 30% reduction policy would bring about an O3 increase in the southern and western areas (by +4.7 ppb at PIZ site and +2.1 ppb at LLH station), and an O3 decrease in the urban center (by −1.7 ppb at GY station and −2.5 ppb at DS station) and in the northern and eastern areas (by −1.2 ppb at MYX station), mainly through interfering with the circulation of atmospheric HOx radicals. While the contribution of the total VOCs emission of PIZ to ozone is greatly prominent in the PIZ and its surrounding areas along south-north direction (12.7% at PIZ site on average), but slight in the other areas of Beijing (<3% in other four stations on average).

LCA of a multifunctional bioenergy chain based on pellet production

This paper investigates the environmental performance of a multifunctional bioenergy chain for the provision of domestic heat using Life Cycle Assessment methodology. The analysis is based on a commercial pellet plant located in Spain and incorporating a Combined Heat and Power system based on Organic Rankine Cycle technology that also produces electricity that is sold to the grid. The base scenario involves using pine wood both from forests and wood processing activities. This situation is compared against a conventional pellet plant with no Combined Heat and Power, using poplar wood from a Short Rotation Coppice plantation and also using the ash produced in the pellet plant as a surrogate fertilizer. The base scenario has also been compared against domestic heat provision from conventional systems based on natural gas, diesel and electricity. The results have shown that the most impacting activities in the life cycle of the bioenergy chain are primarily attributable to the pellet making process, followed by biomass production, biomass transport and finally pellet combustion by the final user. Incorporation of the Combined Heat and Power system to the pellet plant has a very limited influence on the environmental performance of the system since the power generation capacity is very limited and environmental savings from power generation are offset by detrimental effects associated with extra biomass consumption. For a conventional pellet plant, the normalized impact value obtained using International Reference Life Cycle Data System methodology is 2.78 E−04 µPt (vs 2.85 E−04 µPt for the base scenario). A similar bioenergy chain based on poplar wood from a Short Rotation Coppice generates higher environmental impact in water resource depletion. This impact category has a decisive weight after normalization, making this alternative highly unfavorable (5.50 E−04 µPt). Utilizing the ash fraction produced in the pellet plant as a surrogate fertilizer implies low environmental benefits (2.71 E−04 µPt).When compared against heating systems based on diesel, natural gas or electricity (heat pump), the pellet system benefits from reduced impacts on global impact categories like climate change, ozone depletion and Cumulative Energy Demand. However, the bioenergy system performs worse on local impact categories such as particulate matter formation, human toxicity, photochemical ozone formation, freshwater eutrophication and land use. Normalized impact values suggest that the bioenergy system is the least favorable environmental option (2.85 E−04 µPt) as compared to heating systems based on diesel, natural gas or electricity (5.72 E−05 µPt, 5.15 E−05 µPt and 1.99 E−04 µPt respectively).

Life cycle assessment of cellulosic ethanol and biomethane production from forest residues

There is a strong need to manage low-value forest residues generated from the management practices associated with wildfire, pest, and disease control strategies to improve both the environmental and economic sustainability of forestlands. The conversion of this woody biomass into value-added products provides a great opportunity to benefit both the environment and economy. This study aimed to assess the environmental impacts of converting forest residues into two renewable fuels, cellulosic ethanol and biomethane, by different biochemical conversion pathways. The energy balances and environmental impacts, including acidification, eutrophication, global warming, and photochemical ozone formation, of the two biorefinery approaches were addressed. This work illustrated the advantages of converting forest residues into biomethane from energy and environmental perspectives. The tradeoff between the economic benefits and potential environmental issues need to be carefully considered.

Commuters’ Personal Exposure to Ambient and Indoor Ozone in Athens, Greece

This pilot study aimed to monitor the residential/office indoor, outdoor, and personal levels of ozone for people living, working, and commuting in Athens, Greece. Participants (16 persons) of this study worked at the same place. Passive sampling analysis results did not indicate any limit exceedance (Directive 2008/50/EC: 120 µg/m3, World Health Organization (WHO) Air Quality Guidelines 2005: 100 µg/m3). The highest “house-outdoor” concentration was noticed for participants living in the north suburbs of Athens, confirming the photochemical ozone formation at the northern parts of the basin during southwestern prevailing winds. The residential indoor to outdoor ratio (I/O) was found to be significantly lower than unity, underlying the outdoor originality of the pollutant. The highest “office-indoor” concentration was observed in a ground-level building, characterized by the extensive use of photocopy machines and printers. Personal ozone levels were positively correlated only with indoor-office concentrations. A clear correlation of personal ozone levels to the time spent by the individuals during moving/staying outdoors was observed. On the other hand, no correlation was observed when focusing only on commuting time, due to the fact that transit time includes both on-foot and in-vehicle time periods, therefore activities associated with increased exposure levels, but also with pollutants removal by recirculating air filtering systems, respectively.

Estatística Multivariada Aplicada ao Estudo da Qualidade do Ar

Resumo O estudo da qualidade do ar de uma cidade envolve diferentes aspectos, como as emissões, as transformações físico-químicas, a meteorologia e a topografia, tornando esse estudo altamente não linear. Em particular, as cidades brasileiras experimentam um mosaico bem distinto do panorama mundial, em função do uso de diferentes combustíveis por nossa frota veicular. Neste estudo, utilizou-se um conjunto de dados coletados por uma estação de monitoramento da qualidade do ar na cidade do Rio de Janeiro, no bairro da Gávea, entre julho e outubro de 2011, em um total de 2240 observações de médias horárias de 11 variáveis. Os dados foram tratados estatisticamente, de forma descritiva e multivariada, de modo a elucidar a correlação entre as variáveis envolvidas. A estatística multivariada empregou a análise dos componentes principais e agrupamentos euclidianos e critérios de Ward. Os resultados indicaram uma alta correlação entre os poluentes primários óxidos de nitrogênio e monóxido de carbono (0,71), evidenciando que possuem a mesma origem veicular e que o monóxido de nitrogênio e o ozônio (0,66) e este com a radiação solar também estão correlacionados (0,41), corroborando a formação fotoquímica do ozônio. Outras correlações são entre a temperatura e a umidade relativa do ar (0,64) e que o ozônio possui uma contribuição de localidades vizinhas, em função da dependência deste com a velocidade do vento (0,59).