Typical Residential Area Research Articles

Exploring the regional cooling efficiency of urban residential vegetation using scenario simulation

The study of the cooling efficiency of vegetation in urban residential areas at a micro-scale is important for improving the thermal environment of those areas. The quantitative analysis of the effect of the layout of different building patterns on the cooling efficiency of green space is particularly crucial. This study takes a typical residential area with a row-column arrangement in Jiangning District, Nanjing City, Jiangsu Province, China, as the research object. Using the ENVI-MET model used for numerical simulation, 15 simulation scenarios were designed based on building orientation, height, and density. The research proposes the methodology of the regional cooling efficiency (RCE) of urban residential vegetation, reveals the daily variation characteristics of the RCE of vegetation in a residential area, and analyzes the factors influencing of regional cooling efficiency. The results showed that the daily variation in RCE for vegetation in the residential area exhibited a single-peak trend. The minimum and maximum RCE values appeared at 6:00 and 14:00, respectively. The average air temperature and building density in the residential area had a significant positive correlation with RCE, while average relative humidity had a negative correlation. Average wind speed, average building height, and average sky view factor showed nonlinear correlations with RCE, and the importance ranking of each factor's effect on RCE was air temperature > relative humidity > building density > wind speed > building height > sky view factor. This study will provide theoretical support for improving the thermal environment in urban residential areas during the urban planning process.

Evaluation of perception and analysis of energy saving potential of nighttime illumination in different types of residential areas: A case study of Dalian, China

The safety, comfort, and sustainability of the nighttime lighting environment in residential areas become increasingly the focus of social concern. This study integrates remote sensing observations, ground measurements, perception evaluations, and grading maps to compare the data of different residential areas, achieving perceptual performance assessment and energy-saving optimization of the lighting environment. The main researches include (1) Comparison of the Feeling of Safety (FoS) and Perceived Lighting Quality (PLQ) in the nighttime light environments of Dalian's residential areas by contrasting characteristics between high and low illuminated neighborhoods, new and old neighborhoods, open and enclosed neighborhoods, and internal and peripheral roads, (2)Establishment of a lighting environment perceptual evaluation model, proposing illuminance ranges for overall residential areas (6.67–17.97 lx), peripheral roads (8.79–24.50 lx), and internal roads (6.45–16.21 lx), (3) Construction a ground horizontal illuminance inversion model for Dalian and generate FoS and PLQ perception grading maps, (4) Within the scope of the study, the residential areas with insufficient, moderate, and excessive lighting account for 24 %, 56 %, and 20 %, respectively. This study provides effective strategies for reducing energy consumption, ensuring nighttime safety, and enhancing the comfort of living and helps to timely identify potential risk points that do not meet the perceptual standards.

Research on the Renewal of Multi-Story High-Density Urban Landscape Based on Property Rights Land—A Case Study of the Self-Built Liu Houses in Zherong, Fujian Province

Unlike in Western countries, land ownership in China is overwhelmingly vested in the state, and individuals cannot directly own private lands and build houses. Therefore, developers will contract the land to the government and build it into collective apartments. Against this backdrop, a different kind of multi-story, high-density self-built residential buildings is widespread in small towns along the southeast coast of China. These buildings were built between 1980 and 2000 by residents who acquired land-use rights from the government for compensation. The uniqueness of these buildings is what makes them incompatible with the most mainstream, government-led urban renewal model in China, resulting in a large area of dilapidated and aging areas. Zherong County, Ningde, Fujian Province, is a typical example town, with a large number of such self-built houses, known locally as Liu Houses. In this study, these residential areas were selected as typical research objects of “characteristics of residential small towns”. Combined with the property rights of the sample cases, the methods of diagram and quantitative analysis are used to summarize the causes of the three types of residential areas from the aspects of regional planning, land division, building construction, and renovation. In the early days, the planning of the Liu House was greatly influenced by the residents, and the construction and renovation of the building was led by the residents, which strengthened the diversity of the style. In the middle period, the government had relatively dominant control over the planning of Liu Houses, and supervision was conducted during the construction and renovation process, resulting in a relatively balanced power between residents and the government. In the later period, the houses were built and operated by the developer, and the residents no longer directly participated in the construction and renovation, so the unity of style was strengthened. At the same time, the study finds that, in the process of the formation of the style of the residential area, on the one hand, the property rights directly affect the style through its own physical land attributes, and on the other hand, it becomes the basis of the game between the government, residents, and the county environment through its own property rights, thus indirectly affecting the style. In conclusion, this paper may provide theoretical support and design reference for the renewal of the characteristic features of residential small towns.

Comparison of falls and risk factors among older adults in urban villages, urban and rural areas of Shantou, China

ObjectiveTo investigate and compare the differences between the incidence of falls, balance and living environment among older persons in urban villages and other types of residential areas. MethodsWe surveyed 580 older adults living in different types of residential areas in Shantou, China, surveying basic information, fall incidence, balance ability testing of older persons, home environment safety assessment. ResultsThe incidence of falls among older people in urban villages (19.54 %) was between urban areas(26.63 %) and rural areas(16.91 %). The influencing factors of falls in different residential types were different. Near-fall, abnormal bowel movement, and impaired balance ability were the risk factors of falls among older persons in urban villages. Divorce/single, fair and poor hearing loss and near-fall were the risk factors of falls in urban older adults. Frailty and impaired balance ability were the risk factors of falls in rural older people. ConclusionsRisk factors for falls in older people vary according to the characteristics of their living areas and relevant interventions should be targeted according to the characteristics of falls occurring in different residential areas.

Urban morphology clustering analysis to identify heat-prone neighbourhoods in cities

Exposure to heat is a major health concern to urban populations. Cities aim to reduce outdoor thermal stress by adapting the built environment, but the spatial heterogeneity within cities makes it difficult to establish universal mitigation strategies. We present a methodology that identifies the hottest neighbourhoods in a city and links them to underlying patterns in urban form and function, to derive heat mitigation measures for individual neighbourhoods according to their characteristics, mitigation potential, and average surface temperature. The method applies k-means clustering and is applicable to any city using available datasets on surface cover and building morphology, as well as globally available satellite measurements of surface temperatures. Here, we present a heat-mitigation analysis for the city of Zurich. The clustering differentiates seven neighbourhood types, including two types of residential areas, modern neighbourhoods with high-rise buildings, historical districts, and industrial zones. The hottest temperatures are in neighbourhoods with extensive impervious ground cover such as railway tracks and airport parking. Surface temperatures strongly correlate with impervious surface cover and vegetation cover for all neighbourhoods, with building cover only for non-industrial built neighbourhoods, and with sky-view factor for all neighbourhoods except those with large vegetation cover. Historical, modern, and industrial neighbourhoods are particular heat-prone, and increasing vegetation for evaporative cooling is a suggested mitigation strategy for all. Modern and industrial areas could benefit from shading through increase of tree cover, while historical centres may adapt vertical greening as suitable heat mitigation strategy.

Urban ecological human settlements design based on green and low-carbon concept

In recent years, the continuous growth of global carbon emissions has brought about climate change and global ecological environment problems, as well as severe challenges to the development of human settlements. Based on the concept of low carbon, this paper analyzes and summarizes the current situation of green space in typical residential areas, and quantifies its annual carbon sequestration. Then this paper discusses the design optimization strategy to improve its carbon sink efficiency based on the current situation. Finally, the effectiveness and enforce ability of the optimization strategy are verified by estimating the annual carbon sequestration increase value of the green space after the optimization strategy is applied to an example. The method has a certain reference value for the design and research of urban ecological human settlements with the concept of green and low carbon.

A Study on the Effect of Green Plot Ratio (GPR) on Urban Heat Island Intensity and Outdoor Thermal Comfort in Residential Areas

Greenery impacts the urban thermal environment, but the benefits of the three-dimensional green volume of space have not been effectively evaluated. In this paper, we analyzed the impact of 3D greenery on urban heat island intensity and thermal comfort in residential areas from the perspective of the green plot ratio (GPR). We selected a typical residential area, set up simulation models, and then analyzed the effect of different GPR values on the outdoor thermal environment using the validated ENVI-MET simulation. The results showed that increasing GPR in residential areas can effectively reduce the intensity of urban heat island and improve thermal comfort. When the GPR reaches 0.5 and 1.5, the thermal comfort level of the building overhead space and the north–south street space decreases from “very strong thermal stress” to “strong thermal stress”. When the GPR reaches 2.5, the outdoor thermal comfort of the east–west street space and courtyard space is reduced to “hot”. When the GPR is higher than 0.5, the urban heat island intensity in the north–south street space decreases by one level, from “very strong” to “strong”. When the GPR reaches 3.5, all four types of spaces have “moderate” urban heat island intensity. Increased GPR exacerbates urban heat island intensity to some extent and worsens outdoor thermal comfort due to the nocturnal insulating effect of plants. Based on the results, the study proposes the bottom-line control of the GPR index from the perspective of urban heat island mitigation and thermal comfort improvement. This paper points out the benefits of GPR in residential areas in improving the human environment, which is of great practical value for developing urban residential environment from “increasing quantity” to “improving quality”.

COVID-19 vaccine uptake in Skåne county, Sweden, in relation to individual-level and area-level sociodemographic factors: a register-based cross-sectional analysis

ObjectivesBetter understanding of societal factors associated with COVID-19 vaccination can have important implications for public health policy to increase uptake.MethodsThis study investigated sociodemographic determinants of COVID-19 vaccine uptake with ≥2...

Air Pollutants and Risk of Parkinson's Disease among Women in the Sister Study.

Air pollutants may contribute to the development of Parkinson's disease (PD), but empirical evidence is limited and inconsistent. This study aimed to prospectively investigate the associations of PD with ambient exposures to fine particulate matter with aerodynamic diameter () and nitrogen dioxide (). We analyzed data from 47,108 US women from the Sister Study, enrolled from 2003-2009 (35-80 years of age) and followed through 2018. Exposures of interest included address-level ambient and in 2009 and their cumulative averages from 2009 to PD diagnosis with varying lag-years. The primary outcome was PD diagnosis between 2009 and 2018 (). We used multivariable Cox proportional hazards and time-varying Cox models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). exposure in 2009 was associated with PD risk in a dose-response manner. The HR and 95% CI were 1.22 (95% CI: 1.03, 1.46) for one interquartile [4.8 parts per billion (ppb)] increment in , adjusting for age, race and ethnicity, education, smoking status, alcohol drinking, caffeine intake, body mass index, physical activity, census region, residential area type, area deprivation index (ADI), and self-reported health status. The association was confirmed in secondary analyses with time-varying averaged cumulative exposures. For example, the multivariable adjusted HR for PD per increment in was 1.25 (95% CI: 1.05, 1.50) in the 2-year lag analysis using cumulative average exposure. Post hoc subgroup analyses overall confirmed the association. However, statistical interaction analyses found that the positive association of with PD risk was limited to women in urban, rural, and small town areas and women with percentile ADI but not among women from suburban areas or areas with percentile ADI. In contrast, exposure was not associated with PD risk with the possible exception for women from the Midwest region of the US (, 95% CI: 1.20, 5.14) but not in other census regions. In this nationwide cohort of US women, higher level exposure to ambient is associated with a greater risk of PD. This finding needs to be independently confirmed and the underlying mechanisms warrant further investigation. https://doi.org/10.1289/EHP13009.

The Effect of Greening Layout on Microclimate in Urban Residential Areas in Hot Summer–Cold Winter Zones

Appropriate greening design can enhance the microclimate of residential areas. This study investigated different greening cases for residential buildings in hot summer–cold winter zones. Four sorts of greening layouts were tested in a residential area in Chongqing, China. Arbor–grass mix and arbor–shrub–grass mix showed effective cooling and humidifying effects, and were chosen for further study using the ENVI-met model. The simulations were conducted in Chongqing, comparing sixteen greening cases for determinant and enclosed building forms. Results indicate that the greening design for determinant layout should give priority to ensuring the greening area and shortening the distance from the sidewalk. While enclosed layout should concentrate greening in dense populations, using arbor–shrub–grass mix to improve the wind environment. In cases where the distribution of arbors and shrubs covers a ratio of 7:4, constituting 30% of the overall green space, there is a reduction in environmental temperature by 1.4 °C and in PET by 4.8 °C. This study provides the optimal greening layout for two types of residential areas in China’s hot summer–cold winter zones, guiding landscape construction in these residential areas to optimize the microclimate.

AI-Based Evaluation of Streets for People in Bangkok: Perspectives from Walkability and Lingerability

Bangkok, the capital of Thailand, grapples with several urban challenges, including traffic accidents, congestion, and underdeveloped sidewalks. These issues stem from the escalating use of private cars and motorcycles driven by rapid urbanization, accompanying economic growth, and the unique street geometry of the city. Furthermore, despite the development of railroads, issues persist with the poor walking environment for pedestrian access to stations, posing a challenge to the promotion of safe and environmentally friendly public transportation. This study evaluated streets’ spatial performance, focusing on the performance of soi, the intricate network of narrow urban pathways in Bangkok. Leveraging an AI model capturing pedestrian value, this study subsequently assessed accessibility from typical residential areas to public transportation stations. The findings shed light on the challenges faced by sois in Bangkok. Based on the findings, practical implications were discussed and provided to inform urban designers, with the aim of promoting public transportation usage and encouraging a more sustainable urban form.

Effect of visual landscape factors on soundscape evaluation in old residential areas

The visual landscape influences the soundscape experience of urban public spaces. The purpose of this study is to analyze the relationships among visual landscape factors and soundscape evaluation of old residential areas and determine their main influencing factors. In Tianjin, China, six typical old residential areas were selected to collect sound and video information. Virtual reality (VR) was used to create an evaluation environment, and subjective evaluations of the visual landscape and soundscape were accessed through questionnaire (N = 256). The results show that the evaluation of soundscape and visual landscape satisfaction of the central square in the old residential area is superior to that of the public space along the street, as affected by spatial location, sound characteristics and other factors. Greenery satisfaction, environmental cleanliness, and architectural aesthetics were significantly positively correlated with soundscape evaluation. Additionally, three latent variables, namely, visual landscape factors, spatial factors and soundscape evaluation factors, were identified through factor analysis, and a structural equation model (SEM) of “visual landscape factors–soundscape evaluation” was built. The visual landscape factors in old residential areas were found to be important factors affecting soundscape evaluation. The standardization coefficient was 0.46 (P ≤ 0.01). Although the spatial factors have no direct contribution to the soundscape evaluation of the old residential areas, its observation variable, environmental cleanliness, is significantly positively correlated with all the observed variables of the soundscape evaluation factors.

The potential of the height-to-width ratio as an indicator to characterize the ventilation performance of a canyon in the urban context

The height-to-width ratio (H/W) of canyons has been proven to be a significant indicator related to ventilation performance (airflow status and ventilation efficiency), which can help designers assess urban ventilation performance and guide the design quickly. However, previous research focused on the canyons in ideal geometric settings rather than in the urban context. This study explores whether the relationships between H/W, airflow status, and ventilation efficiency of ideal form studies apply to canyons in the urban context. Firstly, the relationship between the three in ideal geometric settings is sorted out by literature reviews. Then, the validity of the findings of ideal form studies in in the urban context is verified, using a typical residential area, Nanjing, China, as a case. This study found that H/W can affect the ventilation performance to a certain extent in in the urban context. However, most canyons’ airflows are affected by complex environmental factors, turning into different flow types (Deviation Type, Crossing Type, and Multivortex Type), which reduces the correlation between H/W, airflow status, and ventilation efficiency of canyons in the urban context.

Impact of NO2 emissions from household heating systems with wall-mounted gas stoves on indoor and ambient air quality in Chinese urban areas

Nitrogen dioxide (NO2) has been discussed as a typical indoor pollutant for decades. As an increasingly popular heating method, household heating system (HHS) with wall-mounted natural gas stoves has led to a continuous increase in the emission of NO2. The absence of legal regulations and strict limits for NO2 emissions from wall-mounted gas stoves has led to a significant exceedance of indoor NO2 concentrations beyond the permissible value. However, this issue is rarely taken into consideration. In this study, we present the first report on NO2 emissions from wall-mounted gas stoves for household heating and their impact on indoor and ambient air quality in Chinese urban areas based on in-situ measurements and numerical simulations. On heating days, the observed indoor NO2 concentration is within 80-200 μg/m3, much higher than the outdoor atmospheric concentration. With a low emission grade of the wall-mounted gas stoves, it is estimated that >10 % of residents in a typical residential building area are exposed to a high NO2 concentration of >200 μg/m3, and >50 % of residents are exposed to a concentration of >80 μg/m3. In addition, the indoor NO2 concentration shows an obvious non-uniform distribution with the floor in residential buildings. The NO2 emission from residential natural gas heating also shows an obvious impact on the microenvironment around buildings, which is primarily determined by the emission grade of the stoves. The findings highlight that HHS has become a non-negligible source of indoor NO2 pollution in China. It is urgently necessary to formulate NO2 emission limit standards for wall-mounted gas stoves in Chinese urban areas and upgrade traditional natural gas heaters with efficient emission reduction technologies.

Designing residential areas using geospatial modelling

The subject of the paper is design using modelling methods of geographic information system (GIS). The authors propose using GIS modelling as a method to solve the actual problem of designing housing estates in a big city. The purpose of the paper is to design a model of a residential area with a complete infrastructure and all necessary elements. In the paper, the following tasks are solved: 1) developing design of a digital geoinformation model of a projected residential area; 2) formalization of the process of designing residential areas by developing a design algorithm; 3) creation of a visual two-dimensional model of a residential area. The method used in the paper is geoinformation modelling of real estate objects using two-dimensional models in a geodatabase, and software implementation using the ArcMap application. As a result of the research, the authors obtained the following results: a centric approach to planning a semi-autonomous region was chosen as the most rational and effective for urban planning. To solve the problem, the geographic information system ArcGIS was used, and a geodatabase was created to analyse the existing territory of the city of Kharkiv and select a construction site. The developed geographic information system ArcGIS and the created geodatabase help in solving the issues of further designing the location of buildings and infrastructure elements of the area. Namely, “buffer zones” were used for further accommodation of schools, kindergartens, and shops. The use of “buffer zones” made it possible to optimally place these establishments depending on the number of potential visitors. The authors chose blocks for the division and development of the projected area, considering the historical aspects of the city of Kharkiv. This enabled to develop a GIS in which each block would have its urban ecosystem. The authors have also developed an algorithm for performing design tasks of residential areas. The algorithm can be applied when creating projects for residential areas not only in Kharkiv, but also in other cities of Ukraine and the world. Results of the research made it possible to use the capabilities of geoinformation systems in designing new types of residential areas with a highly developed social and transport infrastructure, harmonious development, as well as attractive features for stakeholders and future residents. Thus, the developed GIS visualization will enable a visual representation on the map of all spatial objects, which are necessary for analysis, and to reflect spatial patterns of the placement of all necessary infrastructure facilities.

Effect of the Visual Landscape and Soundscape Factors on Attention Restoration in the Public Space of Old Residential Areas by VR

The purpose of this study is to analyze the relationship between the visual landscape and soundscape factors of the public spaces in old residential areas and their attention restoration benefits for residents and to determine the main influencing factors. In this paper, the public spaces of six typical old residential areas in Tianjin were selected as the research object, and the restorative benefits of the respondents were analyzed through virtual reality environment, subjective evaluation, and attention testing methods. The results showed that the attention restoration benefits of the central square in the old residential area were better than those of the public space along the street. Second, greenery satisfaction, environmental cleanliness, architectural aesthetics, sky visibility, and soundscape evaluation are all significantly positively correlated with the attention restoration level. Finally, a "visual landscape and soundscape perception evaluation-attention restoration level" structural equation model was constructed. According to the model, both the visual landscape factors and soundscape evaluation factors in old residential areas had a direct positive impact on the attention restoration level, with a greater impact exerted by visual landscape factors than by soundscape evaluation factors. The findings from this study can provide significant information for the renewal of old residential areas.

Understanding community level influences on the prevalence of SARS-CoV-2 infection in England: new insights from comparison over time and space.

Understanding and monitoring the major influences on SARS-CoV-2 prevalence is essential to inform policy making and devise appropriate packages of non-pharmaceutical interventions. Through evaluating community level influences on the prevalence of SARS-CoV-2 infection and their spatio-temporal variations in England, this study aims to provide some insights into the most important risk parameters. We used spatial clusters developed in Jahanshahi and Jin (2021 Transportation 48, 1329-1359 (doi:10.1007/s11116-020-10098-9)) as geographical areas with distinct land use and travel patterns. We also segmented our data by time periods to control for changes in policies or development of the disease over the course of the pandemic. We then used multivariate linear regression to identify influences driving infections within the clusters and to compare the variations of those between the clusters. Our findings demonstrate the key roles that workplace and commuting modes have had on some of the sections of the working population after accounting for several interrelated influences including mobility and vaccination. We found communities of workers in care homes and warehouses and to a lesser extent textile and ready meal industries and those who rely more on public transport for commuting tend to carry a higher risk of infection across all residential area types and time periods.

Measuring the relationships between various urban green spaces and local climate zones

Urban green spaces (UGS) improve living conditions in cities by mitigating the Urban Heat Island effect. While the cooling effect of UGS seems unequivocal, the relationship between the types of UGS and types of residential areas has not yet been well explored. In this study, we systematically analysed the cooling effect of 71 UGS in Prague, a central European city, on residential areas within 400 m of the UGS. The UGS are classified according to their spatial characteristics (size, shape, and tree density), and the residential areas according to three Local Climate Zones (LCZ 2, 5, 6) typical for European cities. The cooling effect is evaluated using a regression model of the Land Surface Temperature (LST) in residential zones according to the LCZ type and distance from the various UGS. The results show that compact UGS of 10–25 ha with dense trees have the most pronounced cooling effect. This type of UGS was associated with a mean decrease in LST within 400 m of 2.3 °C compared to the least effective UGS type (long with sparse trees) across LCZs. The results of the presented study can be applied in urban planning and urban design to improve microclimates in cities.

Land use-based characterization and source apportionment of microplastics in urban storm runoffs in a tropical region

Urban stormwater runoff has been suggested as one important land-based pathway of microplastics (MPs) entering the oceans, in which the abundance and characteristics of MPs may be influenced by urban land use types. However, little information has been reported regarding this, especially in the tropical monsoon region. This study first reports the MPs in urban stormwater runoffs in a tropical monsoon region that were collected from four typical urban land use types, including industrial, highways, commercial, and residential areas. The average MP particle count and mass concentration were measured as 4.7 ± 3.5 particles/L and 3.8 ± 2.9 mg/L, respectively. MP abundances showed clear urban land use gradients following the order of industrial > transportation > commercial > residential area. In terms of the seasonal variation in MP abundances, a slightly increasing particle count in the dry season was noted for the residential site. Source apportionment of MPs in stormwater runoffs was demonstrated based on the land use type, particle morphology, and chemical compositions. With the simple apportionment approach, approximately 85% of the MP sources were able to be identified in the industrial, transportation, and residential sites. However, the commercial site showed high variability in terms of the morphology and polymer type of MPs. Furthermore, significantly positive correlations between MP abundance and runoff turbidity, TSS, COD, and rainfall intensity were identified, while, no significant correlation was found between MP characteristics and selected water quality/meteorological parameters.

Urban areas as sources of the groundwater contaminants N,N-dimethylsulfamide (N,N-DMS) and 1,2,4-triazole

Urban pollution from biocides used in building materials has raised emerging concern within recent years. The evidence that the use of biocides can pollute urban groundwaters is very limited, but in Denmark, the common degradation product from the two fungicides tolylfluanid and dichlofluanid, N,N-DMS, is particularly abundant in groundwater within urban areas, which suggests an urban source in addition to its well-known agricultural sources. In addition, another widespread groundwater pollutant, 1,2,4-triazole, may originate from the fungicides propiconazole and tebuconazole, that are also used in outdoor paint and wood protection products. To study the potential pollution of groundwater from fungicides used in outdoor paint and wood protection products, we surveyed concentrations in groundwater in two urban areas, we tested leaching from facades and soil concentrations close to facades and fences, and in lab-experiments, we determined the fate of N,N-DMS and 1,2,4-triazole under different redox conditions in soil sampled down to 7 m below surface.Shallow urban groundwater contained up to 1 μg/L N,N-DMS with concentrations of 0.1–0.3 μg/L below a typical Danish residential area. Despite a phase-out of tolylfluanid and dichlofluanid in paint in 2015, both compounds still wash-off wooden facades and fences and was detected in soil next to the treated wood. Much higher soil concentrations, however, were found for propiconazole and tebuconazole and their common degradation product 1,2,4-triazole, reflecting the fact that they are still in use in outdoor paint and wood protection products. 1,2,4-Triazole also leached to groundwater, but concentrations decreased sharply with depth, probably due to degradation that occurred at all tested soil depths and redox conditions. N,N-DMS, on the other hand, was not degraded in deeper soil layers or under anoxic conditions. Consequently, N,N-DMS may persist in groundwater below populated areas well into the future.