Green gentrification in European and North American cities.

Although urban greening is universally recognized as an essential part of sustainable and climate-responsive cities, a growing literature on green gentrification argues that new green infrastructure, and greenspace in particular, can contribute to gentrification, thus creating social and racial inequalities in access to the benefits of greenspace and further environmental and climate injustice. In response to limited quantitative evidence documenting the temporal relationship between new greenspaces and gentrification across entire cities, let alone across various international contexts, we employ a spatially weighted Bayesian model to test the green gentrification hypothesis across 28 cities in 9 countries in North America and Europe. Here we show a strong positive and relevant relationship for at least one decade between greening in the 1990s-2000s and gentrification that occurred between 2000-2016 in 17 of the 28 cities. Our results also determine whether greening plays a "lead", "integrated", or "subsidiary" role in explaining gentrification.

Mental Health Outcomes in Barcelona: The Interplay between Gentrification and Greenspace.

Greenspace is widely related to mental health benefits, but this relationship may vary by social group. Gentrification, as linked to processes of unequal urban development and conflict, potentially impacts health outcomes. This study explores the relationships between greenspace and mental health and between gentrification and mental health associations. It also further examines gentrification as an effect modifier in the greenspace-mental health association and SES as an effect modifier in the gentrification-mental health association. We used cross-sectional Barcelona (Spain) data from 2006, which included perceived mental health status and self-reported depression/anxiety from the Barcelona Health Survey. Greenspace exposure was measured as residential access to (1) all greenspace, (2) greenways and (3) parks in 2006. Census-tract level gentrification was measured using an index including changes in sociodemographic indicators between 1991 and 2006. Logistic regression models revealed that only greenways were associated with better mental health outcomes, with no significant relationship between mental health and parks or all greenspace. Living in gentrifying neighborhoods was protective for depression/anxiety compared to living in non-gentrifying neighborhoods. However, only residents of gentrifiable census tracts benefited from the exposure to greenways. SES was not found to be an effect modifier in the association between gentrification and mental health. Future research should tackle this study's limitations by incorporating a direct measure of displacement in the gentrification status indicator, accounting for qualitative aspects of greenspace and user's perceptions. Gentrification may undermine the health benefits provided by greenspace interventions.

Natural outdoor environments' health effects in gentrifying neighborhoods: Disruptive green landscapes for underprivileged neighborhood residents.

BACKGROUND: Cities are restoring existing natural outdoor environments (NOE) or creating new ones to address diverse socio-environmental and health challenges. The idea that NOE provide health benefits is supported by the therapeutic landscapes concept. However, several scholars suggest that NOE interventions may not equitably serve all urban residents and may be affected by processes such as gentrification. Applying the therapeutic landscapes concept, this study assesses the impacts of gentrification processes on the associations between NOE and the health of underprivileged, often long-term, neighborhood residents. METHODS: We examined five neighborhoods in five cities in Canada, the United States and Western Europe. Our case studies were neighborhoods experiencing gentrification processes and NOE interventions. In each city, we conducted semi-structured qualitative interviews on NOE interventions, equity/justice, gentrification and health (n = 117) with case study neighborhood residents, community-based organizations, neighborhood resident leaders and other stakeholders such as public agencies staff. RESULTS: Respondents highlighted a variety of interconnected and overlapping factors: the insufficient benefits of NOE to counterbalance other factors detrimental to health, the use of NOE for city branding and housing marketing despite pollution, unwelcomeness, increase of conflicts, threats to physical displacement for themselves and their social networks, unattractiveness, deficient routes, inadequate NOE maintenance and lack of safety in NOE. CONCLUSIONS: Our study demonstrated that underprivileged neighborhood residents were perceived to experience new or improved NOE as what we call "disruptive green landscapes" (i.e. non-therapeutic landscapes with which they were not physically or emotionally engaged) instead of as therapeutic landscapes.

Adapting the environmental risk transition theory for urban health inequities: An observational study examining complex environmental riskscapes in seven neighborhoods in Global North cities.

Theories of epidemiologic transition analyze the shift in causes of mortality due to changes in risk factors over time, and through processes of urbanization and development by comparing risk factors between countries or over time. These theories do not account for health inequities such as those resulting from environmental injustice, in which minority and lower income residents are more likely to be exposed to environmental hazards or have less access to environmental goods. Neighborhoods with histories of environmental injustice are also at risk for gentrification as they undergo environmental improvements and new greening projects. We aimed to understand how environmental injustice, urban renewal and green gentrification could inform the understanding of epidemiologic risk transitions. We examined 7 case neighborhoods in cities in the United States and Western Europe which were representative in terms of city region and type, which 1) had experienced a history of environmental injustice and 2) exhibited evidence of recent processes of urban renewal and/or gentrification. In each city, we conducted semi-structured qualitative interviews (n = 172) with city representatives, activists, non-profits, developers and residents. Respondents reported health implications of traditional (heavy pollutants, poor social conditions), transitional (decontamination, new amenities), new (gentrification, access to amenities), and emerging (displacement, climate-related risks, re-emergence of traditional exposures) exposures. Respondents reported renewed, complexified and overlapping exposures leading to poor mental and physical health and to new patterns of health inequity. Our findings point to the need for theories of environmental and epidemiologic risk transitions to incorporate analysis of trends 1) on a city-scale, acknowledging that segregation and patterns of environmental injustice have created unequal conditions within cities and 2) over a shorter and more recent time period, taking into account worsening patterns of social inequity in cities.

Under one canopy? Assessing the distributional environmental justice implications of street tree benefits in Barcelona.

Street trees are an important component of green infrastructure in cities, providing multiple ecosystem services (ES) and hence contributing to urban resilience, sustainability and livability. Still, access to these benefits may display an uneven distribution across the urban fabric, potentially leading to socio-environmental inequalities. Some studies have analyzed the distributional justice implications of street tree spatial patterns, but generally without quantifying the associated ES provision. This research estimated the amount of air purification, runoff mitigation and temperature regulation provided by circa 200,000 street trees in Barcelona, Spain, using the i-Tree Eco tool. Results were aggregated at neighborhood (n = 73) and census tract (n = 1068) levels to detect associations with the distribution of five demographic variables indicating social vulnerability, namely: income, residents from the Global South, residents with low educational attainment, elderly residents, and children. Associations were evaluated using bivariate, multivariate and cluster analyses, including a spatial autoregressive model. Unlike previous studies, we found no evidence of a significant and positive association between the distribution of low income or Global South residents and a lower amount of street tree benefits in Barcelona. Rather, higher ES provision by street trees was associated with certain types of vulnerable populations, especially elderly citizens. Our results also suggest that street trees can play an important redistributive role in relation to the local provision of regulating ES due to the generally uneven and patchy distribution of other urban green infrastructure components such as urban forests, parks or gardens in compact cities such as Barcelona. In the light of these findings, we contend that just green infrastructure planning should carefully consider the distributive implications associated with street tree benefits.

Determining the health benefits of green space: Does gentrification matter?

Urban green space is demonstrated to benefit human health. We evaluated whether neighborhood gentrification status matters when considering the health benefits of green space, and whether the benefits are received equitably across racial and socioeconomic groups. Greater exposure to active green space was significantly associated with lower odds of reporting fair or poor health, but only for those living in gentrifying neighborhoods. In gentrifying neighborhoods, only those with high education or high incomes benefited from neighborhood active green space. Structural interventions, such as new green space, should be planned and evaluated within the context of urban social inequity and change.

Are green cities healthy and equitable? Unpacking the relationship between health, green space and gentrification.

While access and exposure to green spaces has been shown to be beneficial for the health of urban residents, interventions focused on augmenting such access may also catalyse gentrification processes, also known as green gentrification. Drawing from the fields of public health, urban planning and environmental justice, we argue that public health and epidemiology researchers should rely on a more dynamic model of community that accounts for the potential unintended social consequences of upstream health interventions. In our example of green gentrification, the health benefits of greening can only be fully understood relative to the social and political environments in which inequities persist. We point to two key questions regarding the health benefits of newly added green space: Who benefits in the short and long term from greening interventions in lower income or minority neighbourhoods undergoing processes of revitalisation? And, can green cities be both healthy and just? We propose the Green Gentrification and Health Equity model which provides a framework for understanding and testing whether gentrification associated with green space may modify the effect of exposure to green space on health.

Life and light: exotic photosynthesis in binary and multiple-star systems.

The potential for Earth-like planets within binary/multiple-star systems to host photosynthetic life was evaluated by modeling the levels of photosynthetically active radiation (PAR) such planets receive. Combinations of M and G stars in (i) close-binary systems; (ii) wide-binary systems, and (iii) three-star systems were investigated, and a range of stable radiation environments were found to be possible. These environmental conditions allow for the possibility of familiar, but also more exotic, forms of photosynthetic life, such as IR photosynthesizers and organisms that are specialized for specific spectral niches.

Inhibition of polygalacturonase from Verticillium dahliae by a polygalacturonase inhibiting protein from cotton.

An extracellular endo-polygalacturonase (PGase) [E.C. 3.2.1.15] was isolated from 18-day-old culture filtrates of Verticillium dahliae and partially purified using gel permeation chromatography. The band responsible for PGase activity was electrophoretically characterized as having a molecular mass of approximately 29 500 and an isoelectric point of 5.4. Kinetic studies indicate a Km of 3.3 mg ml(-1) and Vmax of 0.85 micromol reducing units min(-1) ml(-1) with polygalacturonic acid as substrate. Polygalacturonase inhibitor protein (PGIP) in cotton seedlings was induced by 5 mM salicylic acid and immunochemical analysis indicated high levels in the hypocotyl tissues. PGIP was purified from roots and stems using affinity chromatography with endo-PGase from Aspergillus niger as an immobilised ligand. The purified PGIP contained monomeric and dimeric molecules with molecular masses of 34 and 66 kDa respectively. Purified cotton PGIP inhibited endo-polygalacturonase from A. niger in a non-competitive or mixed manner with an inhibition constant. K(I) of 15 nM. The isolated V. dahliae PGase was, however, inhibited in a positive cooperative manner, indicative of allosteric interactions between the enzyme and the inhibitor protein. In addition to reducing the reaction rate, decreased substrate affinity may contribute to the accumulation of elicitor-active oligouronides.

Multisorbent tubes for collecting volatile organic compounds in spacecraft air.

The sampling capability of Tenax-TA tubes, used in the National Aeronautics and Space Administration's solid sorbent air sampler to trap and concentrate contaminants from air aboard spacecraft, was improved by incorporating two sorbents within the tubes. Existing tubes containing only Tenax-TA allowed highly volatile compounds to "break through" during collection of a 1.5 L air sample. First the carbon molecular sieve-type sorbents Carboxen 569 and Carbosieve S-III were tested for their ability to quantitatively trap the highly volatile compounds. Breakthrough volumes were determined with the direct method, whereby low ppm levels of methanol or Freon 12 in nitrogen were flowed through the sorbent tubes at 30 mL/min, and breakthrough was detected by gas chromatography. Breakthrough volumes for methanol were about 9 L/g on Carboxen 569 and 11 L/g on Carbosieve S-III; breakthrough volumes for Freon 12 were about 7 L/g on Carboxen 569 and > 26 L/g on Carbosieve S-III. Next, dual-bed tubes containing either Tenax-TA/Carbosieve S-III, Tenax-TA/Carboxen 569, or Carbotrap/Carboxen 569 to a 10-component gas mixture were exposed, in dry and in humidified air (50% relative humidity), and percentage recoveries of each compound were determined. The Tenax-TA/Carboxen 569 combination gave the best overall recoveries (75-114% for the 10 compounds). Acetaldehyde had the lowest recovery (75%) of the 10 compounds, but this value was still an improvement over either the other two sorbent combinations or the original single-sorbent tubes.

Carcinogens in spacecraft air.

The health effects of long-term exposure to ionizing radiation during spaceflight are a major concern to NASA, especially for missions beyond low-Earth orbit. Experiments involving astronauts will be conducted during the next few years to improve the risk assessment for exposures to ionizing radiation during flights; however, concomitant exposure to certain airborne chemical carcinogens during these experiments could confound the results of radiation experiments. Carcinogens can reach the spacecraft atmosphere from leaking thrusters, from off-gassing materials, from chemical experiments and from human metabolism. The Johnson Space Center Toxicology Group routinely analyzes atmospheric samples collected aboard spacecraft. The exposure limits for radiomimetic compounds such as benzene are reduced because of the potential interaction between radiation and chemical exposures. Analysis of recent spacecraft air samples indicates that the following carcinogens are often present in measurable concentrations: acetaldehyde, dichloromethane, formaldehyde and isoprene. Occasionally, the carcinogens 1,2-dichloroethane, acrolein, benzene and furan are found in atmospheric samples. During normal operating conditions, the low concentrations of and limited periods of exposure to airborne carcinogens are thought to pose minimal health risks to crew members, and should not confound experiments involving sensitive methods to detect biological effects of ionizing radiation.

Volatile organic contaminants found in the habitable environment of the Space Shuttle: STS-26 to STS-55.

The health and performance of spacecraft crews can be adversely affected by contaminants present in the respirable air. Contaminants originate from hardware offgassing, crew and microbial metabolism, use of utility chemicals, leakage from fluid systems and payload experiments, and from electrical overheating. The quality of Shuttle air is measured by collecting contaminants in evacuated cylinders or on sorbent resin for later ground-based analysis by gas chromatography (GC) and GC mass spectrometry (MS). The results of those analyses are presented for 28 missions, including 5 Spacelabs which were flown in the payload bay of the Shuttle. The major contaminants were relatively nontoxic alcohols (ethanol, isopropanol), ketones (acetone, diacetone alcohol), alkanes, halocarbons (Halon 1301, Freon 113), and siloxanes. Occasionally, more toxic contaminants, such as methanol, acetaldehyde, and tetrachloroethene, were present at low concentrations (below 1 mg/m3). The contaminant concentrations measured in spacecraft air were compared to spacecraft maximum allowable concentrations (SMAC's) which are set to protect the crew from adverse health effects or performance decrements. Aggregate toxicity assessments (T values) of the contaminants present during each mission, calculated by summing the ratios of measured concentrations to each contaminant's SMAC, showed that air quality consistent met the criterion that the T value be less than 1.

Pyrolysis-gas chromatography/mass spectrometry analyses of biological particulates collected during recent space shuttle missions.

Biological particulates collected on air filters during shuttle missions (STS-40 and STS-42) were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). A method was developed for identifying the atmospheric particles and their sources through the analysis of standard materials and the selection of "marker" compounds specific to the particle type. Pyrolysis spectra of biological standards were compared with those of airborne particles collected during two space shuttle missions; marker compounds present in the shuttle particle spectra were matched with those of the standards to identify the source of particles. Particles of 0,5--1-mm diameter and weighing as little as 40 micrograms could be identified using this technique. The Py-GC/MS method identified rat food and soilless plant-growth media as two sources of particles collected from the shuttle atmosphere during flight.

A breath sampling device for measuring human exposure to volatile organic compounds in microgravity.

A compact device for the collection of alveolar air (breath) from humans aboard spacecraft was developed. The system uses silicone one-way valves that operate independent of gravity, and provide minimal backpressure. Small charcoal filters clean ambient air used for inhalation. The device provided good recoveries of organic compounds at the 20 ng/L level, with generally low carryover of these compounds to a blank sample following a sample at exposure to 100 ng/L. When water accumulated in the system, this carryover increased for highly water soluble compounds. The new device was used in parallel with a larger, previously developed alveolar air sampler that requires gravity for proper operation; comparable results were obtained with the two units. The device measures 47 x 34 x 11.4 cm and weighs approximately 3.2 kg. Sufficient space is available within the case to accommodate a number of sample collection options.

Acute, 2-week, and 13-week inhalation toxicity studies on dimethylethoxysilane vapor in Fischer 344 rats.

Dimethylethoxysilane (DMES), a volatile liquid, is used by NASA to waterproof the heat-protective silica tiles and blankets on the Space Shuttle. Acute, 2-wk, and 13-wk inhalation exposures to DMES vapor were conducted in male and female Fischer 344 rats. In the acute study, rats were exposed to 4000, 2000, 1000, 500, or 0 (control) ppm DMES for 4 h and observed for 14 days. There were no deaths. Narcosis and ataxia were observed in rats of the two highest concentrations only. These signs disappeared within 1 h following exposure. There were no DMES-related gross or microscopic tissue lesions in rats of all exposure groups. In the 2-wk study, rats were exposed for 6 h/day, 5 days/wk to 3000, 1000, 300, 100, or 0 ppm DMES. During exposure, narcosis was observed in rats of the 3000 and 1000 ppm groups. There was a mild decrease in body weight gain in rats of the 3000 ppm group. A decrease in platelet count, an increase in bile acids, and reduced weights of the thymus, testis, and liver were observed in rats of the 3000 ppm group. Microscopically, hypospermatogenesis and spermatid giant cells were observed in the seminiferous tubules of the testes of rats exposed to 3000 ppm DMES. In the 13-wk study, rats were exposed 6 h/day, 5 days/wk to 2000, 600, 160, 40, or 0 ppm DMES. During exposure, rats of the 2000 ppm group exhibited mild narcosis and loss of startle reflex. Recovery from these central nervous system signs was rapid. Body weights were mildly decreased for rats of the 2000 ppm group. There were no exposure-related effects in hematology, serum chemistry, or urinalysis. Female rats of the 2000 ppm group had delayed estrous cycles (6 days compared to 5 days in control rats). Noteworthy organ weight changes in rats of the 2000 ppm group included decreases in thymus, liver, and testicular weights; however, pathologic lesions were observed in the testes only. Sperm motility, epididymal sperm count, and testicular spermatid count were dramatically reduced. Microscopic lesions included degeneration of the seminiferous tubular cells, pyknosis or absence of germ cells, and hypospermia in the epididymis. Rats of the 600 ppm group had a slight decrease in thymic weight and a transient decrease in body weight. Results of the acute, 2-wk, and 13-wk inhalation studies indicate DMES concentrations of 1000 ppm and higher produce narcosis that rapidly disappears following exposure. Repeated exposure of rats to DMES at either 3000 ppm for 2 wk or 2000 ppm for 13 wk caused testicular atrophy and hypospermia in male rats. Female rats exposed to 2000 ppm for 13 wk had delayed estrous cycles. Toxicological effects in rats of the 600 ppm group were minimal and equivocal. The 160 ppm concentration was a no-observable-effect level (NOEL) for 13 wk of exposure to DMES.

Air quality assessments for two recent Space Shuttle flights.

Degradation of air quality in the Space Shuttle environment through chemical contamination and high solid-particulate levels may affect crew performance and health. A comprehensive study of the Shuttle atmosphere was undertaken during the STS-40 (Spacelab Space Life Sciences 1) and STS-42 (Spacelab International Microgravity Laboratory 1) missions to determine the effectiveness of contaminant control procedures by measuring concentrations of volatile organic compounds and analyzing particulate matter trapped on air filters. Analysis of volatile contaminants showed that the air was toxicologically safe to breathe during both missions with the exception of one period during STS-40 when the Orbiter Refrigerator/Freezer was releasing noxious gases into the middeck. Chemical analyses of selected particles collected on air filters facilitated their positive identification. Trace amounts of rat hair and food particles were found in the STS-40 Spacelab filters; a trace amount of soilless plant-growth media was detected in the STS-42 Spacelab filter. The low levels of particles released from these Spacelab experiments indicate that containment measures were effective.

Ion mobility spectrometry of hydrazine, monomethylhydrazine, and ammonia in air with 5-nonanone reagent gas.

Hydrazine (HZ) and monomethylhydrazine (MMH) in air were monitored continuously using a hand-held ion mobility spectrometer equipped with membrane inlet, 63Ni ion source, acetone reagent gas, and ambient temperature drift tube. Response characteristics included detection limit, 6 ppb; linear range, 10-600 ppb; saturated response, >2 ppm; and stable response after 15-30 min. Ammonia interfered in hydrazines detection through a product ion with the same drift time as that for MMH and HZ. Acetone reagent gas was replaced with 5-nonanone to alter drift times of product ions and separate ammonia from MMH and HZ. Patterns in mobility spectra, ion identifications from mass spectra, and fragmentation cross-sections from collisional-induced dissociations suggest that drift times are governed by ion-cluster equilibria in the drift region of the mobility spectrometer. Practical aspects including calibration, stability, and reproducibility are reported from the use of a hand-held mobility spectrometer on the space shuttle Atlantis during mission STS-37.

Acute inhalation toxicity of 3,3-dimethyl-2-butanol in Sprague-Dawley rats.

Sprague-Dawley rats were given 15, 70 and 140 min exposures to 15 mg/l 3,3-dimethyl-2-butanol, pinacolyl alcohol (PA), or 6-hour exposures to 0.2, 1.0 and 5.0 mg/l PA (1 mg/l = 240 ppm). A 50% mortality rate was obtained at the longest exposure to 15 mg/l. Sex related differences in the blood levels of PA and pinacolone were noted, and the surviving male rats failed to gain weight normally in the first week after exposure. In rats exposed to 5.0 mg/l for 6 hours, there were reductions in horizontal and vertical activity and the minute volume was 55% of controls at the end of exposure. Like many secondary alcohols, PA poses only a possible inhalation hazard; however, male rats may be somewhat more susceptible than females.

A 13-week vapor inhalation study of 3,3-dimethyl-2-butanol in Sprague-Dawley rats.

Four groups of male and female Sprague-Dawley rats were exposed for 13 weeks to 3,3-dimethyl-2-butanol (PA) at concentrations of 0.00, 0.20, 1.00 or 5.00 mg/l (1 mg/l = 240 ppm). Exposures were for 6 hr per day, 5 days per week with sacrifices at 7 and 13 weeks of exposure, and at 4 weeks after exposure. The test animals were evaluated for abnormalities in physiology, behaviour, clinical laboratory parameters, and gross and microscopic morphology. No abnormalities were detected in electrocardiograms, respiratory indices, spontaneous activity, passive avoidance activity and open-field behaviour. Clinical signs related to PA exposure included alopecia, ataxia and lacrimation. There were no biologically significant between-group differences in body-weights during the study. The clinical laboratory data demonstrated a 30% increase in serum cholesterol and bilirubin at 7 weeks in high-dose males and an increase in urea nitrogen in intermediate and high-dose males at 13 weeks. There were no abnormalities in hematologic or coagulation parameters. At necropsy there were no significant gross abnormalities; however, examination of organ weights revealed enlarged kidneys in high-dose male rats at 13 weeks, enlarged ovaries in high-dose female rats at 13 weeks, and microscopic study of tissue sections revealed minimal to mild renal tubular injury in high and possibly intermediate dose males at several sacrifices. These findings suggest that the primary target organ of PA, when given by inhalation, is the kidney in male rats and possibly the ovary in female rats. The renal changes in the high-dose males were not fully reversible during the recovery period.(ABSTRACT TRUNCATED AT 250 WORDS)