Comparison Of Indoor Research Articles

Investigation into personal exposure to ultrafine particle (UFP) in Phnom Penh, Cambodia: A pilot study

This pilot study aimed to examine personal exposure to ultrafine particles (UFP or particle smaller than 100 nm) in Phnom Penh, Cambodia through the assessment of different transportation modes, travel routes, and the comparison of indoor and outdoor activities. A handheld UFP counter was used to record the UFP size, concentration and as well as Lung Deposited Surface Area (LDSA). GPS data was recorded using a GPS watch and then combined with the UFP data before further analysis with geospatial software (QGIS) along with OpenStreetMap to generate spatial data of personal exposure to UFP. The study revealed significant differences in UFP exposure between motorbike and bus users, with average UFP concentrations of approximately 114,300 and 171,700 particles/cm³ for motorbike users, and 22,600 and 37,200 particles/cm³ for bus users on lines 3 and 4A, respectively. These concentrations exceed WHO guidelines, which consider UFP levels above 20,000 particles/cm³ per hour as high and potentially harmful. The results of our study also revealed varying amounts of exposure on different roadways, with Russian Federation Blvd consistently exhibited the highest concentrations of UFP, especially during periods of peak traffic. Furthermore, indoor environments generally presented lower UFP exposure. Specific activities or events were found to generate temporary increases in particle concentration. It was shown that weekdays had elevated levels of UFP compared to weekends. Regardless of the limitations of the study, especially its small sample size, it provides significant initial observations, highlighting the urgent need for mitigation strategies and further comprehensive studies in the region.

The microbiome of Total Suspended Particles (TSP) and its influence on the respiratory microbiome of healthy office workers.

Air particulate matter (PM) is widely recognized for its potential to negatively affect human health, including changes in the upper respiratory microbiome. However, research on PM-associated microbiota remains limited and mostly focused on PM (e.g., PM2.5 and PM10). This study aims to characterize for the first time the microbiome of Total Suspended Particles (TSP) and investigate the correlations of indoor TSP with the human upper respiratory microbiome. Biological and environmental samples were collected over three collection periods lasting three weeks each, between May and July 2022 at the University of Milan and the University of Insubria Como. TSP were sampled using a filter-based technique, while respiratory samples from both anterior nares (AN) and the nasopharynx (NP) were collected using swabs. Microbiome analysis of both human (N = 145) and TSP (N = 51) samples was conducted on metagenomic sequencing data. A comparison of indoor and outdoor TSP microbiomes revealed differences in microbial diversity and taxonomic composition. The indoor samples had higher relative abundance of environmental bacteria often associated with opportunistic infections like Paracoccus sp., as well as respiratory bacteria such as Staphylococcus aureus and Klebsiella pneumoniae. Additionally, both indoor and outdoor TSP samples contained broad spectrum antibiotic resistance genes. Indoor TSP exposure was negatively associated with commensal bacteria and positively associated with Staphylococcus aureus relative abundance. Finally, a correlation between the relative abundance of respiratory bacteria identified in the indoor TSP and the upper respiratory microbiome was found, suggesting a potential interaction between TSP and the upper airways.

Performance Assessment of Cell-Separation Processes for Rear-Contact Solar Cells: Comparison of Indoor and Outdoor Measurements

Half-cell and third-cell modules are the current module technology standard due to their enhanced electrical performance. Also, special module layouts for building or vehicle integrated photovoltaics rely on non-standard cell formats obtained by separation techniques. For either application, interdigitated back-contact (IBC) solar cells are one of the promising cell technologies due to their higher performance and more aesthetic appearance. Thus, a cell separation process, usually employing laser tools, is needed that splits the cells as partial cells are manufactured from full cells. However, this cell cutting also induces additional electrical losses. In this work, we analyze the performance of third cell mini-modules made of IBC cells in comparison to PERC cells as reference. Under standard test conditions (STC), an overall performance gain can only be found for the PERC cells, while current and recombination losses dominate the IBC mini-modules. Outdoor measurements under non-STC conditions reveal reduced performance gains under lower illumination. We show a detailed analysis regarding the performance differences of the IBC and PERC cell technologies at indoor STC and outdoor non-STC test conditions.

Comparison of indoor (refrigerated) versus outdoor winter storage of commercial honey bee, Apis mellifera (Hymenoptera: Apidae), colonies in the Western United States.

Honey bees (Apis mellifera L.) are critical to the pollination of many important crops in the United States, and one crop that demands large numbers of colonies early each year is almonds. To provide adequate numbers of colonies for almond pollination, many beekeepers move colonies of bees to high-density holding yards in California in late fall, where the bees can fly and forage, but little natural pollen and nectar is available. In recent years, high colony losses have occurred in some operations following this management strategy, and alternative approaches, including indoor storage of colonies, have become more commonly used. The current study evaluated colonies kept indoors (refrigerated and/or controlled atmosphere) for the winter compared with those kept outdoors in either Washington or California. Colonies were evaluated for strength (frames of bees), brood area, lipid composition of worker bees, colony weight and survival, parasitic mites (Varroa mites, tracheal mites), and pathogens (Nosema spp.). No differences were found in colony weight, survival, parasitic mite levels, or pathogen prevalence among the treatments. Colonies stored indoors and outdoors in WA had significantly more frames of bees and less brood present after the storage period than colonies stored outdoors in CA. Lipid composition of honey bees stored indoors was significantly higher than colonies stored outdoors in WA or CA. The implications of these findings for overall colony health and improved pollination activity are discussed.

The comparison of indoor and outdoor pyranometer calibration method in Jakarta

The increasing energy crisis motivated people to develop renewable energy, one of the promising renewable energies is solar energy. Considering that Indonesia has the potential for sunlight throughout the year, this country should be able to take full advantage of this solar radiation energy. To discover potential area in Indonesia, good and calibrated equipment are needed such as pyranometer, pyrheliometer etc. The objective of this study is to compare developed method of outdoor and indoor pyranometer calibration responsivity. There are 4 pyranometer calibration methods, one of them is called Continuous Sun and Shade Method (CoSSM). However, this method has never been carried out before, so it is going to be developed by the Agency for Meteorology, Climatology, and Geophysics (BMKG) Indonesia. The CoSSM method utilizes two standard components consist of direct and diffuse irradiance to obtain new responsivity values from calibrated global radiation sensor or so called Unit Under Test (UUT). This experiment used 4 UUT and carried out for 12 days. The new responsivity values then compared with the responsivity value that had been obtained from BMKG indoor calibration accredited by National Accreditation Committee (KAN). The results obtained from calibration process provided the highest percentage difference of 6.2% and the smallest 0.2%. This shows that outdoor calibration in cloudy and polluted conditions in Jakarta still give quite good result.

Experimental study on comparison of indoor and multiple outdoor thermal environments excluding visual and acoustic interference

To make holistic assessment of the urban environment, it is important to consider both indoor and outdoor thermal environment. Outdoor thermal parameters play key roles in high quality urban life. This study concentrates on differences between indoor and outdoor thermal comfort excluding visual and acoustic interference. An experiment was carried out in indoor climate chamber and three types of outdoor spaces to explore subjective evaluation and physiological parameters of personnel. Subjects can achieve higher thermal comfort and are less sensitive to the change of thermal parameters outdoors. In a wide range of operative temperature and wind speed in outdoor thermal environment, subjects can be more inclined to stay outdoors. With VR glasses on between 27.5 and 33.5 ℃ under direct sunlight, people feel significantly cooler. In this study, VR glasses and noise-cancelling earphones were used in a pioneering way to exclude the influence of visual and auditory factors and comprehensively compare indoor and outdoor thermal comfort. According to the results, outdoor thermal environment can bring more comfort than indoor air conditioning environment, which highlights the importance of improving outdoor thermal environment. The benefits of comfortable outdoor thermal environments compared with indoor neutral environments can be further explored.

Comparison of Indoor vs Outdoor Induction of Labour in Full Term Uncomplicated Pregnancies.

Background: Induction of labour is an obstetric intervention when the continuation of pregnancy seems to be less beneficial than delivery. Cervical ripening increases the rate of success of labour and normal vaginal delivery. Outpatient cervical ripening is a striking option with benefits of increase maternal satisfaction, reduce hospital stay workload on health care resources Aim: To compare the fetomaternal outcome of indoor vs outdoor induction Methods: An observational cross sectional study was conducted in MCH PIMS, after taking approval from ethical review board from July 1, 2019 to December 31, 2019. A total of 412 women with singleton pregnancy of cephalic presentation and full term gestation were included. Group A was retained in emergency after induction (outdoor patient) while group B (indoor patient) induction was done in ward. All women followed till delivery and fetomaternal outcome i.e. cesarean section, apgar score <7 at 5 minutes, meconium aspiration syndrome and NICU admission (yes/no) were noted. Results: In this study, caesarean section was recorded in 44(21.36%) patients with outdoor induction while in 67(32.52%) in women with indoor induction, Apgar score <7 at 5 minutes was recorded in 4(1.94%) vs 15(7.28%) respectively, meconium aspiration syndrome in 6(2.91%) vs 35(16.99%) respectively and NICU admission in 3 (1.46%) versus 23(11.17%) respectively Conclusion: This study concluded that outdoor induction is better in terms of fetomaternal outcome as compared to indoor induction. Keywords: Induction of labour, outdoor, cesarean section.

A comparison of indoor and outdoor calf housing systems using automated and manual feeding methods and their effect on calf health, behavior, growth, and labor.

Housing and feeding are integral to calf rearing, and must meet calf needs while remaining functional for the farmer. This study compared health, behavior, growth, and labor requirements of calves housed in groups indoors and fed via an automatic or manual milk feeding system compared to calves manually fed in individual or group hutches outdoors. Seventy-six (49 Holstein Friesian [HF] and 27 HF × Jersey) dairy heifer calves were balanced for birth weight (35.2 ± 4.95 kg), birth date (1 February ± 7.2 d) and breed. The experiment was a randomized block design with four treatments; 1) indoor group housing with automated feeding (IN_AUTO; 12 calves per pen), 2) indoor group housing with manual feeding (IN_MAN; 12 calves per pen), 3) outdoor group hutch with manual feeding (OUT_G_MAN; 8 calves per pen), and 4) outdoor individual hutch with manual feeding (OUT_I_MAN; 6 calves: 1 per pen). Calves in OUT_treatments moved outdoors at 18 d (± 5.9 d). Each treatment was replicated once. Milk allowance increased gradually from 6 to 8 L/day (15% reconstitution rate) with ad libitum fresh water, concentrates, and hay offered from 3 d old. Gradual weaning occurred at 8 wk old. Measurements were divided into period 1; before movement outdoors, and period 2; after movement outdoors. Health was similar among treatments, regardless of period, with the most frequent score being zero (i.e., healthy). Summarized, standing and lying were observed 24.3% and 29.8%, respectively, in OUT_I_MAN calves, compared to 8.0% and 49.1%, for the other systems, which were similar. No difference in bodyweight (BW) existed between treatments, except at weaning where BW was lower for OUT_I_MAN (67.4 ± 2.84 kg) compared to IN_MAN (74.2 ± 2.01 kg), and day 102 where OUT_I_MAN (94.1 ± 2.85 kg) were lighter than IN_AUTO (101.1 ± 2.10 kg) (P = 0.047). Total labor input was greatest for OUT_I_MAN (00:02:02 per calf per day; hh:mm:ss) and least for IN_AUTO (00:00:21 per calf per day) (P < 0.001). The labor for feeding (00:00:29 per calf per day), feeding inspection (00:00:10 per calf per day), and cleaning equipment (00:00:30 per calf per day) was greatest for OUT_I_MAN. All calves showed good health and growth patterns. Differences in behavior expressed by calves in the OUT_I_MAN, compared to other treatments may indicate compromised welfare. Thus, although outdoor group hutches do not negatively impact calves, indoor housing, particularly using automated feeders, can improve labor efficiency.

Comparison of indoor and outdoor polycyclic aromatic hydrocarbons from multiple urban residences in Northern China: Coastal versus inland area

Passive air and dust samples were simultaneously collected from urban residences in three functional areas at a coastal site (Weihai) and an inland site (Heze) in Northern China. Samples were concurrently collected in bedrooms, kitchens, and an adjacent outdoor area for each home during the non-heating and heating seasons. Nineteen polycyclic aromatic hydrocarbons (PAHs) were studied by gas chromatography-mass spectrometry (GC-MS). The higher concentrations of PAHs occurred in inland than coastal and industrial area than other districts. The PAHs were more concentrated in outdoor air samples in both cities, but the opposite trend was observed in the dust samples. Compared with bedrooms, higher concentrations of gas-phase PAHs occurred in kitchen. PHE (36.4%) and FLU (18.0%) were the dominant PAHs measured in air samples, whereas middle molecular weight PAHs (34.0%) and high molecular weight PAHs (44.3%) were greater in dust bound PAHs. The I/O ratios of 2–3 rings PAHs in the air were greater than 4–7 rings in both cites indicating that indoor sources had a greater impact on low molecular weight PAHs. The positive matrix factorization (PMF) model identified vehicle exhaust and biomass/coal combustion as the main PAH sources in both outdoor air and dust samples while cooking and solvent use contributed more to indoor samples. Dermal contact with dust accounted for 79.1–85.1% of the total incremental lifetime cancer risk (ILCR) in the study area. Children's ingestion risk was 1.34 and 1.37 times that of adults for both indoor and outdoor sampling areas, respectively.

A comparison of indoor and outdoor biology education: What is the effect on student knowledge, attitudes, and retention?

ABSTRACT This study investigated the effects of outdoor education on a 10th grade biology curriculum in terms of the knowledge, attitudes, and retention of students compared to indoor teaching. The quasi-experimental design included three groups: experiment (OE; N = 43), control-II (indoor teaching; N = 35), and control-I (no application; N = 35). A multiple-choice knowledge test and biology attitude scale assessed the changes in knowledge and attitudes. The experiment and control-II groups took pre-, post-, and retention-tests, whereas the control-I group took pre- and retention-tests. Overall, the experiment group’s knowledge and attitudes were more positively affected than those of control-II. Outdoor Education had a more positive effect on retention and attitudes than did indoor teaching; it took less time and was more economical and temporarily more efficient. Adding Outdoor Education to secondary education biology curricula would increase students’ knowledge and positive attitudes. Cooperation between policy makers and universities is necessary for its effective application.

Assessment of airborne bacterial and fungal communities in different wards of educational hospitals: A case study in Urmia, Iran

Introduction: Bioaerosols consist of aerosols which are biologically originated and can be present ubiquitously in different environments, including the indoor air of hospitals. The objective of this study was to survey the bioaerosol type and density in various environments of four governmental educational hospitals in Urmia, Iran, namely the intensive care unit (ICU), operating room, the internal medicine room, the infectious diseases room, the infectious diseases corridor, and ambient air. Materials and methods: Sampling was performed during summer and winter of 2019 at four different day-times using passive (sedimentation plate) and active methods (an Andersen one-stage viable impactor and Quick Take30 sampling instrument) and by counting plates containing a bacterial and fungus-selective medium. Results: The results revealed that the highest microbial bioaerosol load was related to the infectious diseases corridor (100 and 150 CFU/m3 for total bacterial and fungal load, respectively). The highest bacterial and fungal density was observed in the afternoon at 17-18; and the concentration of bioaerosols was higher in summer than winter. A comparison of indoor and outdoor bacterial loads showed that the indoor bacterial concentration mean (49.1±23.8 CFU/m3 ) was higher than the outdoor value (47.1±21.5 CFU/m3 ), and the indoor levels of fungal contamination (83.3±31.9 CFU/m3 ) were significantly lower than outdoor values (182.5±48.0 CFU/m3 ). The predominantly isolated bacteria were Staphylococcus (95%) spp, and the main isolated fungi belong to the genera Aspergillus (50%) and Penicillium (32%). Conclusion: The results of this study can be useful in developing indoor air microbial quality guidelines in hospitals, which has not been done so far.

Comparison of indoor and outdoor oxidative potential of PM2.5: pollution levels, temporal patterns, and key constituents

Oxidative potential (OP) of PM2.5 is an emerging health indicator representing its ability to induce oxidative stress and cause adverse health effects. We examined pollution levels, temporal variations, and key constituents of PM2.5 OP by DTT assay in both indoor and outdoor environments in Nanjing, China, for over one year. Outdoor OPM (mass-normalized OP characterizes toxicity) and OPV (volume-based OP characterizes overall oxidative burden) in Nanjing were at a medium level compared to results reported for twenty-seven cities. Although PM2.5 mass concentration consistently decreased during outdoor-to-indoor transport, OPM varied by a factor of up to 2 in either direction, indicating a change of PM2.5’s ability to disrupt oxidative-reductive balance. Temporally, both outdoor and indoor OPM exhibited a significant seasonality pattern (P < 0.01) as autumn > summer > spring > winter. Outdoor and indoor daytime-nighttime OPV and OPM are fluctuating within two-fold range. In addition, the change in water-soluble Fe had the highest correlation coefficient (P < 0.05) with ΔOPM (ΔOPM = OPM, in-OPM, out) among constituents measured here. Our results suggest that development of mitigation strategies take indoor PM2.5’s OP into account, instead of outdoors only, since they differ.

Analysis and Risk Assessment of PM2.5-Bound PAHs in a Comparison of Indoor and Outdoor Environments in a Middle School: A Case Study in Beijing, China

People spend most of their time in indoors and, as a result, indoor air quality has become an issue of increasing concern. Due to the use of coal and heavy transportation in Beijing, China, concentrations of polycyclic aromatic hydrocarbons (PAHs) bound to PM2.5 have risen and caused concerns about health risk, both outdoors and indoors. This study carried out quantitative investigation of PM2.5-bound PAHs in middle school classrooms and estimated the health risk to adolescents. According to the results, indoor PM2.5 concentrations ranged from 20.9 μg/m3 to 257.6 μg/m3, indoor PAH concentrations ranged from 8.0 ng/m3 to 83.0 ng/m3, and both were statistically correlated with outdoor concentrations. Results of diagnostic ratios (DR) and the PMF (positive matrix factorization) model indicated that coal combustion was the main source of PAHs in the classroom environment. The average value of incremental lifetime cancer risk (ILCR) was estimated to be 1.49 × 10−6, which indicated a potential health risk to students according to USEPA standards. Predictions showed that by 2021–2022, the risk will be reduced to an acceptable level. Results of this study could provide useful information for air pollution control in Beijing and proposing targeted solution against indoor air pollution.

The feline cutaneous and oral microbiota are influenced by breed and environment.

Previous research revealed the feline skin bacterial microbiota to be site-specific and the fungal microbiota to be individual-specific. The effect of other factors, such as genotype and environment, have not yet been studied in cats, but have been shown to be potentially important in shaping the cutaneous microbiota of other animals. Therefore, the objectives of this study were to evaluate the effect of these factors on the bacterial and fungal microbiota of feline skin and oral cavity. The influence of genotype was assessed through the analysis of different cat breeds, and the influence of environment through comparison of indoor and outdoor cats. DNA was extracted from skin and oral swabs, and bacterial and fungal next-generation sequencing were performed. Analysis of the skin microbiota of different cat breeds revealed significant differences in alpha diversity, with Sphynx and Bengal cats having the most diverse communities. Many taxa were found to be differentially abundant between cat breeds, including Veillonellaceae and Malassezia spp. Outdoor environment exposure had considerable influence on beta diversity, especially in the oral cavity, and resulted in numerous differentially abundant taxa. Our findings indicate that the oral bacterial microbiota and both fungal and bacterial microbiota of feline skin are influenced by breed, and to a lesser degree, environment.

Evaluation of Indoor Air Pollution during Decorating Process and Inhalation Health Risks in Xi’an, China: A Case Study

ABSTRACT PM2.5, formaldehyde, and 8 volatile organic compounds (VOCs) were observed in 6 newly decorated apartment units to evaluate the effects of the decorating process on the indoor air quality in Xi’an, China. The comparison of indoor and outdoor formaldehyde and VOCs concentrations showed that the outdoor PM2.5 concentration exceeded the indoor one during the monitoring process, whereas the indoor formaldehyde and VOCs concentrations exceeded the outdoor ones. The levels of formaldehyde and VOCs in different rooms were investigated, and the concentrations in the bedroom were found to be the highest. Furthermore, the formaldehyde and VOCs concentrations were measured in 200 other rooms decorated within a 2-year period in Xi’an, and the results indicated that wallpapering, wooden flooring, and furniture were the major decorating processes emitting these compounds. In addition, a health risk assessment of the monitored formaldehyde and VOCs in the rooms 1 year after decorating showed that benzene posed the greatest health risk among the assessed VOCs.

The identification of Volatile Organic Compound’s emission sources in indoor air of living spaces, offices and laboratories

Indoor air quality is important because people spend most of their time in closed rooms. If volatile organic compounds (VOCs) are present at elevated concentrations, they may cause a deterioration in human well-being or health. The identification of indoor emission sources is carried out by comparison indoor and outdoor air composition. The aim of the study was to determinate the concentration of VOCs in indoor air, where there was a risk of elevated levels due to the kind of work type carried out or the users complained about the symptoms of a sick building followed by an appropriate interpretation of the results to determine whether the source of the emission in the tested room occurs. The air from residential, office and laboratory was tested in this study. The identification of emission sources was based on comparison of indoor and outdoor VOCs concentration and their correlation coefficients. The concentration of VOCs in all the rooms were higher or at a similar level to that of the air sampled at the same time outside the building. Human activity, in particular repair works and experiments with organic solvents, has the greatest impact on deterioration of air quality.

Performance Evaluation of LTE based System Parameters using OFDM in Indoor and Outdoor Environment

Background/Objectives: OFDM is a wireless broad band technology employed in 4G wireless system. OFDM is the Frequency Division Multiplexing (FDM) modulation technique used for sending a group of signals simultaneously over a channel. OFDM divides the signal into a number of narrow signals which are sent at various frequencies to the receiver. Method/Analysis: Long Term Evolution is a 4G technology used for both indoor and outdoor environments. LTE is able to produce higher data output rates and reduce the cost of delivering a megabyte of data. The outside sources of interference, design and configuration of the LTE network may reduce the spectrum efficiency and results in low data output rates for users and high costs for network operators. LTE will be deployed to provide multimedia services for mobile and portable scenarios. Findings/Applications: This paper concentrates on correlating SNR to the performance of LTE in indoor and outdoor environments. An average throughput and a consistent performance are observed more frequently in outdoor areas when compared to indoor areas. A comparison of indoor and outdoor parameters is shown by simulating in MATLAB.

Un télémètre transportable de résolution submicrométrique

This paper describes a transportable system based on synthetic wavelength interferometry for absolute distance measurement. The synthetic wavelength is generated by means of two frequency-doubled Nd:YAG lasers. A superheterodyne technique has been implemented to detect the synthetic phase, enabling a fringe interpolation of ∼2π/5 600. A ∼5 μm accuracy (1σ) is demonstrated over 25 m, based on an indoor comparison with a classical fringe counting interferometer. An outdoor comparison has been carried out on a 864 m-long standard baseline located in Finland (Nummela), yielding an uncertainty of 700 μm (1σ). This work was carried out within the framework of the “Long distance” EMRP project that ended on June 2011.

The Future of Pork Production in the World: Towards Sustainable, Welfare-Positive Systems.

Simple SummaryMore pork is eaten in the world than any other meat. Making production systems and practices more sustainable will benefit the animals, the planet and people. A system is presented by which production practices are evaluated using a sustainability matrix. The matrix shows why some practices are more common in some countries and regions and the impediments to more sustainable systems. This method can be used to assess the sustainability of production practices in the future where objective, science-based information is presented alongside ethical and economic information to make the most informed decisions. Finally, this paper points to current pork production practices that are more and less sustainable.Among land animals, more pork is eaten in the world than any other meat. The earth holds about one billion pigs who deliver over 100 mmt of pork to people for consumption. Systems of pork production changed from a forest-based to pasture-based to dirt lots and finally into specially-designed buildings. The world pork industry is variable and complex not just in production methods but in economics and cultural value. A systematic analysis of pork industry sustainability was performed. Sustainable production methods are considered at three levels using three examples in this paper: production system, penning system and for a production practice. A sustainability matrix was provided for each example. In a comparison of indoor vs. outdoor systems, the food safety/zoonoses concerns make current outdoor systems unsustainable. The choice of keeping pregnant sows in group pens or individual crates is complex in that the outcome of a sustainability assessment leads to the conclusion that group penning is more sustainable in the EU and certain USA states, but the individual crate is currently more sustainable in other USA states, Asia and Latin America. A comparison of conventional physical castration with immunological castration shows that the less-common immunological castration method is more sustainable (for a number of reasons). This paper provides a method to assess the sustainability of production systems and practices that take into account the best available science, human perception and culture, animal welfare, the environment, food safety, worker health and safety, and economics (including the cost of production and solving world hunger). This tool can be used in countries and regions where the table values of a sustainability matrix change based on local conditions. The sustainability matrix can be used to assess current systems and predict improved systems of the future.

Transportable Distance Measurement System for Long-Range Applications

This paper describes a transportable distance measurement system based on synthetic wavelength interferometry using two frequency-doubled Nd:YAG lasers. To eliminate polarization crosstalk issue, a different system has been set up from those usually described in the literature. Indeed, we propose a system where the different beams are spatially separated instead of being polarization-separated. Furthermore, the superheterodyne detection is partly software-implemented to measure the synthetic phase, enabling an angular resolution of ~ 2π/5600 in the fringe pattern. A first assessment of the system has consisted in an indoor comparison on a 3-m-long displacement bench, successfully resulting in ~ 4 μm accuracy. Then, the system has been further modified for an indoor comparison over 25 m. Recent measurements are given, limited by now by the pitch angle of the displacement bench used for the comparison.