Types Of Indoor Environments Research Articles

Sim-to-Lab-to-Real: Safe Reinforcement Learning with Shielding and Generalization Guarantees (Abstract Reprint)

Safety is a critical component of autonomous systems and remains a challenge for learning-based policies to be utilized in the real world. In particular, policies learned using reinforcement learning often fail to generalize to novel environments due to unsafe behavior. In this paper, we propose Sim-to-Lab-to-Real to bridge the reality gap with a probabilistically guaranteed safety-aware policy distribution. To improve safety, we apply a dual policy setup where a performance policy is trained using the cumulative task reward and a backup (safety) policy is trained by solving the Safety Bellman Equation based on Hamilton-Jacobi (HJ) reachability analysis. In Sim-to-Lab transfer, we apply a supervisory control scheme to shield unsafe actions during exploration; in Lab-to-Real transfer, we leverage the Probably Approximately Correct (PAC)-Bayes framework to provide lower bounds on the expected performance and safety of policies in unseen environments. Additionally, inheriting from the HJ reachability analysis, the bound accounts for the expectation over the worst-case safety in each environment. We empirically study the proposed framework for ego-vision navigation in two types of indoor environments with varying degrees of photorealism. We also demonstrate strong generalization performance through hardware experiments in real indoor spaces with a quadrupedal robot. See https://sites.google.com/princeton.edu/sim-to-lab-to-real for supplementary material.

Endocrine disrupting potential of total and bioaccessible extracts of dust from seven different types of indoor environment

Information on the indoor environment as a source of exposure with potential adverse health effects is mostly limited to a few pollutant groups and indoor types. This study provides a comprehensive toxicological profile of chemical mixtures associated with dust from various types of indoor environments, namely cars, houses, prefabricated apartments, kindergartens, offices, public spaces, and schools. Organic extracts of two different polarities and bioaccessible extracts mimicking the gastrointestinal conditions were prepared from two different particle size fractions of dust. These extracts were tested on a battery of human cell-based bioassays to assess endocrine disrupting potentials. Furthermore, 155 chemicals from different pollutant groups were measured and their relevance for the bioactivity was determined using concentration addition modelling. The exhaustive and bioaccessible extracts of dust from the different microenvironments interfered with aryl hydrocarbon receptor, estrogen, androgen, glucocorticoid, and thyroid hormone (TH) receptor signalling, and with TH transport. Noteably, bioaccessible extracts from offices and public spaces showed higher estrogenic effects than the organic solvent extracts. 114 of the 155 targeted chemicals were detectable, but the observed bioactivity could be only marginally explained by the detected chemicals. Diverse toxicity patterns across different microenvironments that people inhabit throughout their lifetime indicate potential health and developmental risks, especially for children. Limited data on the endocrine disrupting potency of relevant chemical classes, especially those deployed as replacements for legacy contaminants, requires further study.

Particle size, carbon composition and sources of indoor dust in Nanchang, China

Indoor dust is an enriched environmental media for lots of chemical pollutants, while indoor pollutants pose high exposure level and health risks to humans. In this work, indoor dust samples from four types of indoor environments (residence near steel plant, residence near road, student dormitory and rural kitchen) in Nanchang city were collected and their particle sizes and carbon components were analyzed. The sources of carbon components were traced based on the distribution of carbon components and the correlation between the components. The particle size distribution mainly presents a bimodal mode (0.1–3 and 10–40 μm size intervals, accounting for 8.9% and 7.4%). The average OC and EC in the as-collected indoor dust samples were 34.1 and 52.7 mg/g for residences around the steel plant, 43.9 and 41.4 mg/g for residences adjacent to the road, 119.3 and 66.4 mg/g for students' dormitories, 73.5 and 49.8 mg/g for rural kitchens, respectively. A strong correlation between OC and Char was observed, indicating strong homology between the sources of the two components. In addition, the correlation between two of EC1, OC2, and OC3 (OC2 and OC3 are fractions of OC and EC1 is a fraction of EC) were significant, indicating a large contribution of motor vehicle exhaust to indoor dust. The average ratios of OC/EC and Char/Soot suggest the contribution of automobile exhaust, indoor smoking and biomass combustion to indoor dust. The results of this work provide a scientific, convenient, and reliable approach to explore the source of particulate matter indoors based on the distribution of carbon components.

Relative Role of Age Groups and Indoor Environments in Influenza Transmission Under Different Urbanization Rates in China.

Exploring the relative role of different indoor environments in respiratory infections transmission remains unclear, which is crucial for developing targeted nonpharmaceutical interventions. In this study, a total of 2,583,441 influenza-like illness cases tested from 2010 to 2017 in China were identified. An agent-based model was built and calibrated with the surveillance data, to assess the roles of 3 age groups (children <19 years, younger adults 19-60 years, older adults >60 years) and 4 types of indoor environments (home, schools, workplaces, and community areas) in influenza transmission by province with varying urbanization rates. When the urbanization rates increased from 35% to 90%, the proportion of children aged <19 years among influenza cases decreased from 76% to 45%. Additionally, we estimated that infections originating from children decreased from 95.1% (95% confidence interval (CI): 92.7, 97.5) to 59.3% (95% CI: 49.8, 68.7). Influenza transmission in schools decreased from 80.4% (95% CI: 76.5, 84.3) to 36.6% (95% CI: 20.6, 52.5), while transmission in the community increased from 2.4% (95% CI: 1.9, 2.8) to 45.4% (95% CI: 35.9, 54.8). With increasing urbanization rates, community areas and younger adults contributed more to infection transmission. These findings could help the development of targeted public health policies. This article is part of a Special Collection on Environmental Epidemiology. This article is part of a Special Collection on Environmental Epidemiology.

Sim-to-Lab-to-Real: Safe reinforcement learning with shielding and generalization guarantees

Safety is a critical component of autonomous systems and remains a challenge for learning-based policies to be utilized in the real world. In particular, policies learned using reinforcement learning often fail to generalize to novel environments due to unsafe behavior. In this paper, we propose Sim-to-Lab-to-Real to bridge the reality gap with a probabilistically guaranteed safety-aware policy distribution. To improve safety, we apply a dual policy setup where a performance policy is trained using the cumulative task reward and a backup (safety) policy is trained by solving the Safety Bellman Equation based on Hamilton-Jacobi (HJ) reachability analysis. In Sim-to-Lab transfer, we apply a supervisory control scheme to shield unsafe actions during exploration; in Lab-to-Real transfer, we leverage the Probably Approximately Correct (PAC)-Bayes framework to provide lower bounds on the expected performance and safety of policies in unseen environments. Additionally, inheriting from the HJ reachability analysis, the bound accounts for the expectation over the worst-case safety in each environment. We empirically study the proposed framework for ego-vision navigation in two types of indoor environments with varying degrees of photorealism. We also demonstrate strong generalization performance through hardware experiments in real indoor spaces with a quadrupedal robot. See https://sites.google.com/princeton.edu/sim-to-lab-to-real for supplementary material.

Edge-Computing Meshed Wireless Acoustic Sensor Network for Indoor Sound Monitoring.

This work presents the design of a wireless acoustic sensor network (WASN) that monitors indoor spaces. The proposed network would enable the acquisition of valuable information on the behavior of the inhabitants of the space. This WASN has been conceived to work in any type of indoor environment, including houses, hospitals, universities or even libraries, where the tracking of people can give relevant insight, with a focus on ambient assisted living environments. The proposed WASN has several priorities and differences compared to the literature: (i) presenting a low-cost flexible sensor able to monitor wide indoor areas; (ii) balance between acoustic quality and microphone cost; and (iii) good communication between nodes to increase the connectivity coverage. A potential application of the proposed network could be the generation of a sound map of a certain location (house, university, offices, etc.) or, in the future, the acoustic detection of events, giving information about the behavior of the inhabitants of the place under study. Each node of the network comprises an omnidirectional microphone and a computation unit, which processes acoustic information locally following the edge-computing paradigm to avoid sending raw data to a cloud server, mainly for privacy and connectivity purposes. Moreover, this work explores the placement of acoustic sensors in a real scenario, following acoustic coverage criteria. The proposed network aims to encourage the use of real-time non-invasive devices to obtain behavioral and environmental information, in order to take decisions in real-time with the minimum intrusiveness in the location under study.

Numerical investigation on indoor environment decontamination after sneezing

More than 320 million people worldwide were affected by SARS-CoV-2 or COVID-19, which already caused more than 5.5 million deaths. COVID-19 spreads through air when an infected person breathes, coughs, or sneezes out droplets containing virus. Emerging variants like Omicron with positivity rate of 16 (highest among others) present a greater risk of virus spread, so all types of indoor environments become critically important. Strategically adopted Heating Ventilation and Air Conditioning (HVAC) approach can significantly reduce the virus spread by early removal of contaminated aerosolized droplets. We modeled different HVAC configurations to characterize the diffusion of contaminated droplets cloud through Computational Fluid Dynamics (CFD) simulations of sneeze in standard hospital room as indoor scenario. Injection of saliva droplets with characteristics of exhaled air from lungs was applied to mimic real sneeze. CFD simulations have been performed for three HVAC configurations at two Air Change per Hour (ACH) rates; 6 and 15 ACH. For the first time, use of air curtain at low flow rate has been examined. Simulations provide high fidelity spatial and temporal droplets cloud diffusion under different HVAC configurations, showing spread in room indoor environment up to 360 s. Over 92% of ejected sneeze mass is removed from room air within seconds while the remaining 8% or less becomes airborne with droplets (<50 μm size) and tends to spread uniformly with regular HVAC configuration. Low-speed air curtain accelerates decontamination by efficiently removing aerosolized 1–50 μm size droplets. Study investigates role of droplets removal mechanisms such as escape, evaporation, and deposition on surfaces. Interestingly, results show presence of contaminated droplets even after 5 min of sneeze, which can be effectively removed using low-speed air curtain. Study finds that high ventilation rate requirements can be optimized to modify earlier and new hospital designs to reduce the spread of airborne disease.

Probabilistic health risk assessment and monetization based on benzene series exposure in newly renovated teaching buildings

To meet the needs of the rapid development of education, there have been growing investments in the issue of university infrastructures. However, few studies have paid attention to the assessment and monetization of health risks in newly renovated teaching buildings. In this study, concentrations of the benzene series (BTEX) group were measured in five areas of three newly renovated teaching buildings. A total of 135 BTEX samples were collected using passive diffusion monitors and analyzed by GC–FID. Human health risk assessments were conducted by using probabilistic methods for four types of population exposure to BTEX. The results showed that the cancer risk of benzene accounted for most of the total in each group. There was over 90% probability of excess cancer risks in the areas within the tested buildings; and the non-cancer risks were all within the acceptable level. The health risks of men were greater than those of women, and those of teachers were higher than those of students. The model calculation results of Disability-Adjusted Life Year (DALY) and Willingness to Pay (WTP) indicated that the average price that society was willing to pay to offset the health damage caused in these newly renovated teaching buildings was 381.35 yuan/year. For the first time, this study highlights the health risks of newly built teaching buildings in universities, points out the urgent need to improve the control of BTEX sources in this type of indoor environment; moreover, it provides theoretical support for the society and occupational protection departments to compensate for the health damage to professionals.

Seasonal antimicrobial activity of volatile substances emitted by the representatives of &lt;i&gt;Begonia&lt;/i&gt; L. genus (Begoniaceae)

The paper continues multi-year integrated studies of the numerous taxons of tropical Begonia genus, which allowed us to evaluate the adaptive capacity of the representatives of this genus relying on the revealed morphological, rhythmological and biochemical features. The investigation of antimicrobial activity of intact plants and different fractions of plant extracts allowed us to distinguish several promising representatives of this genus exhibiting activity against a broad range of test microorganisms. The involvement of these plants within phytomodules in child care centers caused a substantial decrease in total microbial contamination of the air. The paper contains results of the experimental investigation of seasonal antimicrobial activity of 13 species, 8 hybrids. The phytoncide activity was measured by exposing the streak cultures of microbial test species bacteria Staphylococcus epidermidis, Esсherichia coli and yeast-like fungi Candida albicans to the volatile emissions of plants. It has been established that 95% of begonias are distinguished by the pronounced activity against S. epidermidis bacteria, 48% against E. coli bacteria and 43% against fungi Candida albicans. The seasonal specificity of the antimicrobial action of begonias was detected: the growth of the colonies of S. epidermidis bacteria is inhibited to the highest extent during spring and summer, at the phase of intense growth, while the activity against E. coli is the highest during autumn and winter at the phase of moderate growth. The taxons with clearly pronounced, long-term and universal antimicrobial action to the studied test objects were revealed and recommended for practical planting in various types of indoor environments. The data obtained in the study may serve as the basis for further investigation of the chemical composition of volatile exometabolites by the example of the representatives of Gireoudia and Coelocentrum sections that have exhibited high antimicrobial activity against S. epidermidis and E. coli.

Indoor occurrence and health risk of formaldehyde, toluene, xylene and total volatile organic compounds derived from an extensive monitoring campaign in Harbin, a megacity of China

Human exposure to formaldehyde, toluene, xylene (FTX) and other volatile organic compounds (VOCs) are associated with negative health impact. To characterize the exposure and health effects of FTX and TVOC from indoor environments, we conducted an extensive monitoring campaign involving 1278 measurements of 472 indoor locations in Harbin, a megacity in China from May 2013 to March 2018. The results showed that household had the highest mean formaldehyde concentration (0.171 ± 0.084 mg m-3) among all types of indoor environments. Meanwhile, there was no significant differences in formaldehyde concentration of the living room, master bedroom, secondary bedroom and study room (p > 0.05), as well as toluene and xylene. The highest mean concentration of toluene, xylene and TVOC was measured in public bath center. Great difference was found between formaldehyde concentrations in 2013 and other years, except 2015. There were great positive nonlinear correlations between the indoor temperature and concentration of formaldehyde (p < 0.01), good negative nonlinear correlations between the finish time of decoration and concentration of formaldehyde (p < 0.01), good positive linear correlations between the relative humidity and concentration of formaldehyde (p < 0.01). A risk assessment methodology was utilized to evaluate the potential adverse health effects of the individual FTX compounds according to their carcinogenicities. The predicted carcinogenic risk of formaldehyde was greater than the threshold value 1E-06 at all environments. The non-carcinogenic risk of TX compounds in the population is negligible. For estimating human health risk exposure, sensitivity analysis showed that more attention should be given to the influential variables such as the level of pollutants.

Wideband Performance Comparison between the 40 GHz and 60 GHz Frequency Bands for Indoor Radio Channels

When 5G networks are to be deployed, the usability of millimeter-wave frequency allocations seems to be left out of the debate. However, there is an open question regarding the advantages and disadvantages of the main candidates for this allocation: The use of the licensed spectrum near 40 GHz or the unlicensed band at 60 GHz. Both bands may be adequate for high performance radio communication systems, and this paper provides insight into such alternatives. A large measurement campaign supplied enough data to analyze and to evaluate the network performance for both frequency bands in different types of indoor environments: Both large rooms and narrow corridors, and both line of sight and obstructed line of sight conditions. As a result of such a campaign and after a deep analysis in terms of wideband parameters, the radio channel usability is analyzed with numerical data regarding its performance.

Mass accretion and ozone reactivity of idealized indoor surfaces in mechanically or naturally ventilated indoor environments

In indoor environments, accretion of mass to materials may provide sites for surface chemistry that differ from those of the original material. Since indoor surfaces are a major sink of oxidant gases, surface mass accretion may impact indoor O3 chemistry. In this study, the effect of surface mass accretion on O3 surface deposition was tested by deploying cleaned borosilicate glass plates in two types of indoor environments: a mechanically ventilated (MV) office and a naturally ventilated (NV) residence located in Singapore. In each environment, seven replicate glass plates and one field blank were deployed for between 7 and 56 days and examined in a laboratory chamber for O3 deposition rate and surface reaction probability. Average mass accretion to plates, deployed in a horizontal position and including deposited particles, was 10.6 mg/(m2 d) in the MV office vs. 18.5 mg/(m2 d) in the NV residence and the comparison is at the threshold of statistical significance (p = 0.054). Ozone reactivity to the plates increased in magnitude and persistence with longer plate deployment. Ozone reaction probabilities to cleaned plates prior to deployment ranged [0.06–0.74] × 10−6 for two hours of observable removal whereas plates deployed for 56 days ranged [0.15–1.2] × 10−6 for four hours of observable removal. Regressions of cumulative O3 removed during chamber tests vs. mass accreted show removal of 4.3 nmol O3/mg for the NV residence and 2.4 nmol O3/mg for the MV office. These results imply that accretion of mass to surfaces may alter indoor O3 transformation pathways.

Privacy-Preserving Top-&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$k$ &lt;/tex-math&gt; &lt;/inline-formula&gt; Route Computation in Indoor Environments

Most of us live our daily lives in various types of indoor environments. With the rapidly increasing air pollution and abnormal weather conditions occurring all over the world, the importance of indoor space is expected to increase in the future. As the importance of indoor spaces has increased, there have been extensive efforts to understand the indoor behavior patterns of individuals by collecting and analyzing their indoor positioning data. However, indiscriminate collection of indoor location information may raise significant privacy issues, because it is possible to infer sensitive information by analyzing their indoor location data. Thus, there is a need to develop a technology capable of: 1) collecting individuals’ indoor positioning data while not violating privacy requirements and 2) analyzing their movement patterns, based on the indoor positioning data set collected in a privacy-preserving manner. Recently, there has been a growing interest in local difference privacy (LDP) that can protect individual privacy in the process of data collection. The main concept of LDP is adding carefully designed noise to sensitive data at the data contributor’s side and directly sending the noisy data to a data collector, guaranteeing that the original data are not exposed to the outside. In this paper, we first develop a method to collect individuals’ indoor positioning information by leveraging LDP, and then, we introduce an effective approach to compute top- $k$ routes between two points in indoor environments by leveraging the indoor positioning data sets collected in an LDP manner. Experimental results show that the proposed approach well exploits the indoor positioning data collected in an LDP-compliant manner, and a good estimation of top- $k$ routes can be achieved with the proposed method and a large data set.

Investigating CO2 removal by Ca- and Mg-based sorbents with application to indoor air treatment

Indoor carbon dioxide (CO2) levels serve as an indicator of ventilation sufficiency in relation to metabolic effluents. Recent evidence suggests that elevated CO2 exposure (with or without other bioeffluents) may cause adverse cognitive effects. In shelter-in-place (SIP) facilities, indoor CO2 levels may become particularly elevated. This study evaluates four low-cost alkaline earth metal oxides and hydroxides as CO2 sorbents for potential use in indoor air cleaning applications. Sorbents studied were MgO, Mg(OH)2, Ca(OH)2 and commercially available soda lime. Uncarbonated sorbents characterized with nitrogen adsorption porosimetry showed BET surface areas in the 5.6–27 m2/g range. Microstructural analyses, including X-ray diffraction, thermogravimetric analysis and scanning electron microscopy confirmed the carbonation mechanisms and extent of sorption under environmental conditions typical of indoor spaces. Ca-based sorbents demonstrated higher extent of carbonation than Mg-based sorbents. Laboratory parameterizations, including rate constants (k) and carbonation yields (y), were applied in material balance models to assess the CO2 removal potential of Ca-based sorbents in three types of indoor environments. Soda lime (k = [2.2–3.6] × 10−3 m3 mol CO2−1 h−1, y = 0.49–0.51) showed potential for effective use in SIP facilities. For example, CO2 exposure in a modeled SIP facility could be reduced by 80% for an 8-h sheltering interval and to levels below 5000 ppm for an 8-h period with a practically sized air cleaner. Predicted effectiveness was more modest for bedrooms and classrooms.

PM 2.5, soot and NO 2 indoor–outdoor relationships at homes, pre-schools and schools in Stockholm, Sweden

In developed nations people spend about 90% of their time indoors. The relationship between indoor and outdoor air pollution levels is important for the understanding of the health effects of outdoor air pollution. Although other studies describe both the outdoor and indoor atmospheric environment, few excluded a priori major indoor sources, measured the air exchange rate, included more than one micro-environment and included the presence of human activity. PM 2.5, soot, NO 2 and the air exchange rate were measured during winter and summer indoors and outdoors at 18 homes (mostly apartments) of 18 children (6–11-years-old) and also at the six schools and 10 pre-schools that the children attended. The three types of indoor environments were free of environmental tobacco smoke and gas appliances, as the aim was to asses to what extent PM 2.5, soot and NO 2 infiltrate from outdoors to indoors. The median indoor and outdoor PM 2.5 levels were 8.4 μg m −3 and 9.3 μg m −3, respectively. The median indoor levels for soot and NO 2 were 0.66 m −1 × 10 −5 and 10.0 μg m −3, respectively. The respective outdoor levels were 0.96 m −1 × 10 −5 and 12.4 μg m −3. The median indoor/outdoor (I/O) ratios were 0.93, 0.76 and 0.92 for PM 2.5, soot and NO 2, respectively. Their infiltration factors were influenced by the micro-environment, ventilation type and air exchange rate, with aggregated values of 0.25, 0.55 and 0.64, respectively. Indoor and outdoor NO 2 levels were strongly associated ( R 2 = 0.71), followed by soot ( R 2 = 0.50) and PM 2.5 ( R 2 = 0.16). In Stockholm, the three major indoor environments occupied by children offer little protection against combustion-related particles and gases in the outdoor air. Outdoor PM 2.5 seems to infiltrate less, but indoor sources compensate.

Behavior-Based Navigation Using Heuristic Fuzzy Kohonen Clustering Network for Mobile Service Robots

This technical note presents a behavior-based navigation method for a mobile service robot with a three-wheeled omnidirectional mobile platform. A heuristic fuzzy Kohonen clustering network (FKCN) is presented to obtain laser area weights and desired robot motion heading for all types of indoor environments. An efficient behavior-based navigation structure is then proposed to merge the heuristic FKCN with three fuzzy behaviors in order to navigate the robot without any collisions in crowded and cluttered indoor environments. Simulation and experimental results are conducted to verify the feasibility and effectiveness of the proposed method.

Differences in the presence of allergens among several types of indoor environments

Exposure to indoor allergens can occur both at home and in public places such as schools and workplaces. To investigate and compare the presence of indoor allergens in different kind of environments (schools, offices and homes), dust samples were collected from furniture, desks, mattresses and floors with a standardized procedure. Samples were analyzed for Der p 1, Der f 1, Mite group 2 (mites) and Fel d 1(cat) by monoclonal antibody ELISA assay. Mite allergens were detected with low frequencies in schools and workplaces and with high frequency in homes. Fel d 1 was found with high frequency in every examined environment. Homes rather than public places can represent the environment where people can easier incur in mite allergy. All environments could be at risk for cat allergen exposure.

Bacteria and Fungi Levels in Various Indoor and Outdoor Environments in Ankara, Turkey

AbstractIn this study, different types of indoor environments (primary school, kindergarten, cafeteria, restaurant, dormitory, dwelling, office, sport salon, library, classroom, and laboratory) and their outdoor environments were investigated in terms of bioaerosol contamination. A total of 120 environments were investigated in Ankara, Turkey. The single‐stage Andersen sampler was used for viable bioaerosol sampling. During the sampling, indoor and outdoor temperature, relative humidity, and CO2 concentration were measured. Total bacteria counts (TBC) and fungi concentrations varied on a large scale within and between the sampling site groups (10–103 CFU/m3). The highest TBC levels were measured in kindergartens, primary schools, restaurants, high schools, and homes, while the highest mold levels were measured in kitchens, bathrooms, and offices. Micrococcus spp., Staphylococcus auricularis, and Bacillus spp. were predominant bacteria species and Penicillium spp., Aspergillus spp., and Cladosporium spp. were the most observed mold genera detected in the samples. Indoor‐to‐outdoor (I/O) ratios of the observed fungi counts were calculated as approximately around 1, and for bacteria counts these ratios were higher than 1. There was no statistical difference between indoor and outdoor mold levels, while a significant difference was found between indoor and outdoor bacteria levels (p &lt; 0.001). A significant correlation between indoor CO2 and bioaerosols indicates insufficient ventilation.

Building Segment-Based Maps Without Pose Information

Most map building methods employed by mobile robots are based on the assumption that an estimate of robot poses can be obtained from odometry readings or from observing landmarks or other robots. In this paper we propose methods to build a global geometric map by integrating scans collected by laser range scanners without using any knowledge about the robots' poses. We consider scans that are collections of line segments. Our approach increases the flexibility in data collection, since robots do not need to see each other during mapping, and data can be collected by multiple robots or a single robot in one or multiple sessions. Experimental results show the effectiveness of our approach in different types of indoor environments.

Medidas dos níveis de radônio em diferentes tipos de ambientes internos na região da Baixada Santista, SP

OBJETIVO: Exposições a altos níveis do gás radioativo radônio podem causar câncer de pulmão e, conseqüentemente, o conhecimento da concentração deste gás em ambientes internos é importante, do ponto de vista de proteção radiológica, para a população de um modo geral. Neste trabalho realizaram-se monitorações passiva e integrada de radônio em alguns tipos de ambientes fechados na região da Baixada Santista, SP, tais como túneis, galpão de fertilizantes, "shopping center", lojas de cerâmica e residências, com o objetivo de se avaliar os níveis de concentração existentes nestes locais. MATERIAIS E MÉTODOS: As medidas de concentração de radônio foram realizadas utilizando a técnica do registro de traços de partículas alfa em folhas plásticas de Makrofol E, na geometria de copo fechado ("cup method"). RESULTADOS: Os teores de radônio encontrados nos ambientes internos estudados neste trabalho variaram entre 17 e 263 Bq/m³, em razoável acordo com os valores divulgados na literatura por outros autores para ambientes similares. CONCLUSÃO: De modo geral, os resultados obtidos estão abaixo dos limites máximos recomendados pela Comissão Internacional de Proteção Radiológica (ICRP), não necessitando, portanto, que sejam implementadas ações de intervenção nos locais estudados.