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Science for Environment Policy’s editorial team.
In this issue
Simple Swedish device effectively reduces harmful indoor air pollution Indoor air quality can be significantly improved using a simple device which traps harmful chemicals emitted from glues, paints and building materials, a new study has shown. Designed in Sweden, the researchers demonstrate that the ‘surface emissions trap’, especially effective for damp buildings, also prevents emissions from mould and can remove unpleasant odours.
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New incineration-waste clean-up method brings resource and carbon benefits Ash from waste incineration can be made safer simply by mixing it with rice husks, water and other forms of waste ash at temperatures under 100 °C, according to new research. Once dried, the end product not only locks away toxic metals lead and zinc, but also stores carbon. Furthermore, it can be used in the polymer industry to lower costs, improve polymer properties and reduce the use of natural resources.
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Older and larger trees enhance woodland bird biodiversity in cities Managing urban green spaces to ensure that they have a good mix of tree species, including some older and larger trees, can enhance species diversity of woodland birds, a new study has shown. The study, carried out in Prague, Czech Republic, also showed that the presence of water bodies increased the number of species of woodland birds.
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Protest votes: why will some people not tell how much they are willing to pay for clean air? What is the value of clean air? Answering such a question may be achieved by asking citizens how much they are willing to pay. However, some individuals give ‘protest vote’ responses to such questions. Recent research in EU countries found that the main reasons for this were because they felt that the polluters themselves or the government should be responsible for such costs.
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Rural inhabitants suffer mental distress under extended droughts Long, unbroken periods of drought can be damaging to the mental health of people living in rural areas, new research suggests. An Australian study found that rural inhabitants who had experienced extensive drought periods over a seven-year period, combined with an unbroken spell for the year before they completed the survey had substantially higher distress scores than other participants.
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Balancing conflicting conservation goals takes time Ecosystems are complex and managing them effectively can mean balancing conflicting conservation goals. In a recent US study in the San Francisco Bay area researchers examine the best strategies to eradicate an invasive plant while protecting an endangered bird that uses it for nesting habitat. They find that with a clear management plan both goals can be achieved, albeit over a longer timeframe.
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Full articles
Simple Swedish device effectively reduces harmful indoor air pollution
Indoor air quality can be significantly improved using a simple device which traps harmful chemicals emitted from glues, paints and building materials, a new study has shown. Designed in Sweden, the researchers demonstrate that the ‘surface emissions trap’, especially effective for damp buildings, also prevents emissions from mould and can remove unpleasant odours.
Volatile organic compounds (VOCs), such as formaldehyde, which can irritate the lungs and may cause cancer, can be emitted from building materials as well as glues and plasticisers used, for example, in PVC flooring. Damp buildings are particularly at risk from indoor air pollution as water can breakdown glue to release these VOCs, as well encouraging the growth of mould. Although replacing moisture-damaged material can reduce emissions, controlling the cause of the dampness might not always be feasible, for example if it is too costly to improve the ventilation in buildings.
This study describes a simple device to reduce emissions from damp building materials. The surface emissions trap is made by layering different materials into a cloth. A central adsorption layer and a breathable polymer sheet are protected top and bottom by a layer of polyester fabric. The cloth is placed directly on to a damp floor or wall and traps emissions from this surface while simultaneously allowing water vapour to pass through it.
The researchers tested the efficiency of the device in removing VOCs from PVC flooring in the laboratory and found it reduced total VOCs by 97%. Concentrations of formaldehyde were also reduced by 98.5% and the chemical 2-chloroanisole – which gives a musty odour – by 99%.
Furthermore, the researchers found that the efficiency of the trap was not impaired at different temperatures (30 and 40°C) or moisture levels (relative humidity levels 35, 60 and 85%). Artificially aging the emissions trap revealed that the device would still work efficiently after at least 10 years of use.
The researchers also tested the trap in a Swedish school built in the 1970s. Staff and pupils had complained about the poor air quality and the cause of the problem was identified as the PVC flooring that had been glued onto the concrete floor. Dampness in the building had been breaking down the glue, releasing VOCs.
The researchers stuck a total of 510m2 of cloth to the floor (which was then covered with laminated flooring) in various rooms in the school building. The researchers took air samples and samples of the emissions trap to test for 2-ethyl-1-hexanol, the main VOC found before installation of the trap.
Two months after installation, levels of airborne 2-ethyl-1-hexanol had fallen from 6-7 µg/m3 to 2 µg/m3 and remained at this level after 13 months of using the emissions trap. Concentrations of the chemical increased in the trap from zero to 280 µg/g after 13 months of use, corresponding to only 1% of the capacity of the device. No mould was detected on the surface of the trap, laminated floor overlay or the PVC flooring. Furthermore, teachers reported that the disagreeable odour had disappeared within a few days of installation.
These results indicate that the device is an effective and easy way to improve indoor air quality, say the researchers, especially in buildings that have been affected by damp.
Source: Markowicz, P. & Larsson, L. (2014). Improving the indoor air quality by using a surface emissions trap. Atmospheric Environment. DOI:10.1016/j.atmosenv.2014.04.056.
New incineration-waste clean-up method brings resource and carbon benefits
Ash from waste incineration can be made safer simply by mixing it with rice husks, water and other forms of waste ash at temperatures under 100 °C, according to new research. Once dried, the end product not only locks away toxic metals lead and zinc, but also stores carbon. Furthermore, it can be used in the polymer industry to lower costs, improve polymer properties and reduce the use of natural resources.
Municipal Solid Waste Incineration (MSWI) produces fine particles of ash, known as fly ash. This hazardous waste is generally landfilled and the search is on to find more sustainable ways of managing this waste.
The new technology for managing fly ash proposed by this Italian study is inexpensive, highly available and effective at detoxifying MSWI, its developers claim. They say it could help meet the objectives of the EU’s Waste Framework Directive, which prioritises re-using and recycling waste materials over disposal. The technology was developed under the EU LIFE+ project, COSMOS-RICE1.
In their method, MSWI fly ash is stirred for an hour with water and a small amount of rice husk ash. Rice husk, a waste product of low commercial value, is a natural source of silica, a material known to stabilise metal contaminants, i.e. it fixes them into a safe form. Globally, around 130 million tons of rice husks are produced – and then burnt – each year.
Some flue gas desulphurisation residue (gathered by filters in industrial flues to improve air quality) and fly ash from coal burning are also added to the mix, to improve the final product’s strength and carbon storage.
Importantly, no raw materials are needed; all ingredients (except the water) are waste products. Furthermore, the rice husk ash is added directly; silica does not need to be extracted from husk ash as a pure ingredient for this stabilisation process, as in earlier trials. Avoiding the extraction step is major progress as the process is energy-intensive and requires toxic chemicals.
The mixture is then dried out at room temperature to form a solid substance which can be used to make construction materials, such as plaster and tiles. The researchers experimented with the temperature of mixing and the length of drying time to see how these factors affected the material. They found that the material was best at stabilising lead and zinc when it had been mixed at 80 100 °C and dried for about one month, compared with lower temperatures and shorter drying periods.
They also created a liquid solution from salts washed out of the material to assess how much zinc and lead the solution contained. When produced under the best stabilising conditions, the solution contained around 0.1-0.2 micrograms of zinc per litre (mg/L) and no lead. In contrast, concentrations in the solution from untreated fly ash are around 17.5 mg/L of zinc and 134 mg/L of lead.
Furthermore, stabilisation sequesters around 100 g of CO2 per kg of fly ash. This helps reduce the process’s carbon footprint, the researchers say.
1.COSMOS-RICE (ENV/IT/256) is supported by LIFE+, the EU’s financial instrument for supporting environmental and nature conservation projects.
Source: : Bosio, A., Zacco, A., Borgese, L. et al. (2014). A sustainable technology for Pb and Zn stabilization based on the use of only waste materials: A green chemistry approach to avoid chemicals and promote CO2 sequestration. Chemical Engineering Journal. 253: 377-384. DOI: 10.1016/j.cej.2014.04.08.
Older and larger trees enhance woodland bird biodiversity in cities
Managing urban green spaces to ensure that they have a good mix of tree species, including some older and larger trees, can enhance species diversity of woodland birds, a new study has shown. The study, carried out in Prague, Czech Republic, also showed that the presence of water bodies increased the number of species of woodland birds.
Urban green spaces provide numerous important ecosystem services. Not only can they enhance human health and well-being and alleviate city heat waves, they also provide habitat for a range of wildlife. As people continue to migrate from rural areas into the cities and urban sprawl extends into natural habitats, the careful management of these areas becomes increasingly important.
In this study researchers set out to identify factors that enhance the diversity of woodland bird species in urban green spaces. They surveyed 290 green spaces around the city of Prague, Czech Republic, counting the number of woodland bird species they saw over three visits to the sites. They also recorded a number of habitat characteristics such as the trunk diameter of the trees (an indication of age), number of tree species, density of shrubs and whether there was a water body at the site.
The results showed that the number of woodland bird species increased with the number of tree species. This may reflect the fact that different tree species provide different types of nesting and foraging opportunities, say the researchers. On average, the sites contained just over 12 species, with a minimum of 3 and a maximum of 19.
Bird species richness also increased with the presence of older trees. Coverage of just 12% of the area by trees that had a trunk diameter of 50 cm or more increased the number of bird species by an average of two. In other words, say the researchers, even a very few old trees can enhance biodiversity of birds in urban green spaces. This effect might be because older trees provide holes for species such as woodpeckers to nest in; they may also harbour more insects for foraging.
The results also reveal that the presence of water bodies such as small ponds, rivers or streams increased the number of species of woodland birds, on average, by two. This is somewhat surprising, say the researchers, as they did not include any wetland birds in their counts. This might reflect the fact that riverside areas provide a greater diversity of foraging habitats.
Finally, the researchers investigated the effects of the surrounding habitats, within 500 m of the study sites. This showed that bird diversity at the sites increased with the amount of continuous tree cover nearby and also with the scattered trees that are found in residential areas of the city.
Overall, the researchers recommend that urban green spaces should be managed to ensure a range of tree species and that the greater value of older, larger trees and water bodies should also be taken into account.
Source: Ferenc, M., Sedlá?ek, O. & Fuchs, R. (2014). How to improve urban greenspace for woodland birds: site and local-scale determinants of bird species richness. Urban Ecosystems. 17: 625–640. DOI: 10.1007/s11252-013-0328-x.
Protest votes: why will some people not tell how much they are willing to pay for clean air?
What is the value of clean air? Answering such a question may be achieved by asking citizens how much they are willing to pay. However, some individuals give ‘protest vote’ responses to such questions. Recent research in EU countries found that the main reasons for this were because they felt that the polluters themselves or the government should be responsible for such costs.
‘Externalities’ are environmental or social welfare costs not directly borne by the manufacturer or consumer. Traffic pollution, for example, is related to externality costs that are not covered by the market prices of transportation, but must be borne by wider society. For instance, air pollution from traffic has been linked to increased risk of heart disease and traffic noise has been associated with high blood pressure and poor school performance in children.
Putting a price on such impacts is far from simple. One of the main methods is asking citizens how much they are willing to pay for environmental goods such as clean air and reduced health impacts.
However, studies have shown that some individuals give ‘protest vote’ responses to such questions, for example indicating that they are willing to pay nothing because they feel that the polluter should be responsible for any such costs. These are different from ‘don’t know’ responses.
As part of the EU-funded INTARESE1 project, researchers conducted a survey of 10 464 people in total from the UK, Finland, Germany, the Netherlands and Spain. Half of the participants received questions about traffic noise and the other half about traffic-related air pollution. Individuals were also asked what they would be willing to pay on an annual basis for the rest of their lives for avoiding, for example, more cases of children with reading difficulties.
Approximately 10% of responses were ‘protest votes’ with around a third (30% for air pollution surveys and 26% for noise surveys) of these giving the reason that the costs should be included in transportation prices. Another third (30% for air pollution and 33% for noise) believed that the government should pay all costs to reduce air pollution and noise. About one fifth were principally against putting an amount of money on health (20% for both air pollution and noise).
The likelihood of giving a protest vote was higher for women, and increased with age and decreased with level of education. Nationality also had an effect and individuals from Finland were less likely to respond with a protest vote. People who gave protest votes had higher concern for the environment and were more likely to disagree with the statement that the government was ‘doing its best to reduce air or noise pollution’. They were also more likely to have a lower income.
1.The INTARESE (Integrated Assessment of Health Risks of Environmental Stressors in Europe) project was supported by the European Commission under the 6th Framework. See: http://www.intarese.org/
Source: : Istamto, T., Houthuijs, D. & Lebret, E. (2014). Multi-country willingness to pay study on road-traffic environmental health effects: are people willing and able to provide a number? Environmental Health. 13:35. DOI: 10.1186/1476-069X-13-35.
Rural inhabitants suffer mental distress under extended droughts
Long, unbroken periods of drought can be damaging to the mental health of people living in rural areas, new research suggests. An Australian study found that rural inhabitants who had experienced extensive drought periods over a seven-year period, combined with an unbroken spell for the year before they completed the survey had substantially higher distress scores than other participants.
The increased frequency and severity of drought under climate change may have many damaging effects for humans. Both water and food security may be threatened, for example, possibly leading to civil unrest or hunger. However, drought may also affect individuals’ health and well-being. For instance, previous Australian research has linked reduced rainfall to a rise in local suicide rates.
In this study researchers investigated the effects of drought on mental health over a seven-year period. Uniquely, they also investigated whether the effects of the ‘drought pattern’ affected people in different ways. Drought pattern included the severity of the drought (relative to usual rainfall in the area) but also the duration and number of particularly dry periods within the on-going drought.
The researchers used data on mental health from a 2007–2008 survey of 5 012 Australians who had lived in the same area for the past seven years. Overall, 4 093 participants lived in urban areas and 919 in rural areas. The authors of the study linked the drought patterns that each respondent had experienced in the seven years before the survey to scores for mental distress, while accounting for other factors such as income, ethnicity and pre-existing mental illness.
The results showed that rural residents experienced a significant rise in mental distress if they had endured an extreme number of months in drought (defined as a total of 20–32 months over the seven years) combined with a period of dryness lasting a year or more in the time before they completed the survey. This may be because people who have endured numerous spells of dryness may begin to doubt their capacity to cope with on-going drought, the researchers say.
This group had a distress score 6.22% greater than other rural participants. This is a substantial difference, the researchers say, as illustrated by the fact that those with pre-existing mental illness had mental distress scores that were 15.59% higher than others.
These effects were not seen for urban dwellers, whose mental distress scores were not significantly influenced by drought. The researchers suggest that this may be because rural inhabitants are much more connected to the environment, both socially and economically. Drought in rural areas can mean starving livestock and failed crops, for instance, with damaging effects across the entire community.
These results are important, the study’s authors say, not only because they provide the first quantitative evidence of the impacts of drought on mental health, but also because they show that it is not necessarily the intensity of the drought that is important to mental health, but the pattern. In particular, a combination of recurrent drought with long, unbroken periods is likely to be damaging, they conclude.
Source: : O’Brien, L.V., Berry, H.L., Coleman, C. & Hanigan, I.C. (2014). Drought as a mental health exposure. Environmental Research. 13: 181–187.
Balancing conflicting conservation goals takes time
Ecosystems are complex and managing them effectively can mean balancing conflicting conservation goals. In a recent US study in the San Francisco Bay area researchers examine the best strategies to eradicate an invasive plant while protecting an endangered bird that uses it for nesting habitat. They find that with a clear management plan both goals can be achieved, albeit over a longer timeframe.
In the 1970s a non-native species of cordgrass (Spartina alterniflora) was planted in the San Francisco Bay area in the US as a way of restoring the salt marshes that had been filled in or altered in the past. S. alterniflora then crossed with native cordgrass S. foliosa and the hybrid became invasive, eventually spreading across more than 300 hectares. An eradication programme started in 2005 and by 2011 around 92% of the invasive hybrid had been removed.
The California clapper rail (Rallus longirostris obsoletus) has been classified as an endangered species in the US, in immediate danger of becoming extinct. Clapper rails nest and forage in cordgrass and their numbers dropped by nearly half during the nine years the invasive cordgrass was being eradicated. Although native cordgrass was replanted in areas cleared of the invasive hybrid, it did not grow quickly enough to form the dense cordgrass meadows preferred by the bird.
The researchers investigated the most cost-effective management strategy that could achieve eradication of the invasive cordgrass while maintaining protection of the endangered clapper rail. They used information on the populations of invasive and native cordgrass from the nine-year eradication programme and calculated the costs of the damage caused by the invasive cordgrass and those of removing it, as well as the costs of restoring the native species.
The researchers found that the best solution required a three-stage management programme:
1) Removal of invasive cordgrass as quickly as possible to reduce the likelihood of further spread, until any further removal would harm the clapper rail by critically reducing its habitat. All of the annual budget should be used for this purpose.
2) Planting native cordgrass in areas that have been totally cleared, until there are sufficient plants to grow into the extensive meadows needed to support the clapper rail. Again, the entire annual budget should be used for this.
3) Carry on removing invasive cordgrass but at a slower pace, while the newly planted native cordgrass has a chance to establish meadows covering enough area to support the clapper rail. This whole process could take many years, possibly over two decades.
This approach can be used in similar situations where conservation goals are in conflict, say the researchers. They also caution that ecosystem managers might need to take longer to ensure several goals can be met as opposed to pursing a single goal as quickly as possible.
Source: Lampert, A., Hastings, A., Grosholz, E.D. et al. (2014). Optimal approaches for balancing invasive species eradication and endangered species management. Science. 344 (6187): 1028-1030.
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