Analysis of Ventilation Efficiency as Simultaneous Control of Radon and Carbon Dioxide Levels in Indoor Air Applying Transient Modelling.

The impact of ventilation efficiency on radon (222Rn) and carbon dioxide (CO2) concentrations in the indoor air of a residential building was studied by applying transient data analysis within the CONTAM 3.4 program. Continuous measurements of 222Rn and CO2 concentrations, together with basic meteorological parameters, were carried out in an apartment (floor area about 27 m2) located in Ljubljana, Slovenia. Throughout the experiment (October 3-15), frequent ventilation (several times per day), poor ventilation (once to twice per day) and no ventilation scenarios were applied, and the exact ventilation and occupancy schedule were recorded. Based on the measurements, a transient simulation of 222Rn and CO2 concentrations was performed for six sets of scenarios, where the design ventilation rate (DVR) varied based on the ventilation requirements and recommendations. On the days of frequent ventilation, a moderate correlation between the measured and simulated concentrations (r = 0.62 for 222Rn, r = 0.55 for CO2) was found. The results of the simulation indicated the following optimal DVRs: (i) 36.6 m3 h-1 (0.5 air changes per hour, ACH) to ensure a CO2 concentration below 1000 ppm and a 222Rn concentration below 100 Bq m-3; and (ii) 46.9 m3 h-1 (0.7 ACH) to ensure a CO2 concentration below 800 ppm. These levels are the most compatible with the 5C_Cat I (category I of indoor environmental quality, defined by EN 16798-1:2019) scenario, which resulted in concentrations of 656 ± 121 ppm for CO2 and 57 ± 13 Bq m-3 for 222Rn. The approach presented is applicable to various types of residential buildings with high overcrowding rates, where a sufficient amount of air volume to achieve category I indoor environmental quality has to be provided. Lower CO2 and 222Rn concentrations indoors minimise health risk, which is especially important for protecting sensitive and fragile occupants.

Determination of optimal ventilation rates in educational environment in terms of radon dosimetry.

INTRODUCTION: New and renovated energy efficient buildings with minimised ventilation rates together with increased building airtightness are often associated with higher indoor radon concentrations compared to the concentrations in existing buildings. The purpose of our study is to analyse the problem associated with the increased radon concentration and ventilation requirements and recommendations in schools. The radon concentration was critically assessed by varying the design ventilation rates (DVRs) within fifteen cases according to legislative requirements and recommendations. The case study is a branch primary school in western part of Slovenia situated in a radon prone area. METHODS: Radon (222Rn) concentrations were simulated in the classroom, using CONTAM 3.2. PROGRAM: For validation, measurements were performed on 8 measuring days in September and 6 measuring days in March. The simulated and measured 222Rn concentrations are well correlated for all measurement days, with the simulated/measured ratio of 0.85-1.39. In order to define optimal DVRs in terms of dosimetry, the effective dose and its ratio to the worldwide average effective dose at workplace, received by radon progeny in 950 h (expected effective dose, 0.13 mSv/y), were calculated for each case. RESULTS: Simulations showed that the highest radon concentrations were observed in case 1 with a DVR of 79.6 m3/h (621 Bq/m3) and case 4 with a DVR of 69.4 m3/h (711 Bq/m3), both defined by national regulations. The calculated values in both cases exceeded the national reference value for radon (300 Bq/m3) by 2.1 times and 2.4 times, and the WHO guideline value (100 Bq/m3) by 6.2 times and 7.1 times, respectively. The simulations are in line with the results of radon dosimetry. Both DVRs correspond to the highest effective doses, 1.88 mSv/y (about 14-fold higher than expected effective dose) for case 1 and 2.15 mSv/y (about 17-fold higher than expected effective dose) for case 4. Case 11_Cat I with a DVR of 1999.7 m3/h defined by EN 15251: 2007 resulted in minimal Rn concentration (35 Bq/m3) and corresponds to the lowest effective dose 0.11 mSv/y and its ratio to the expected effective dose 0.8. CONCLUSIONS: Ventilation is an immediate measure to reduce radon concentration in a classroom and it must be performed in line with other holistic measures to prevent and control radon as a health risk factor.

Sick building syndrome among healthcare workers and healthcare associates at observed general hospital in Slovenia.

OBJECTIVE: The aim of this study was to assess the possible associations between self-perceived sick building syndrome (SBS) symptoms among healthcare workers and healthcare associates and self-perceived parameters of indoor work environment quality. METHODS: The cross-sectional study was conducted from February to April 2019. Validated standardized evaluation tools (MM 040 NA Hospital 2007 and MM 040 NA Office 2007) were used for estimating the prevalence of SBS among observed populations. Chi-square and Mann-Whitney U tests for assessing possible associations in SBS symptoms between healthcare workers and associates were used. RESULTS: The response rate was 69.8%. The results showed a lower prevalence of six or more SBS symptoms in healthcare associates (6.4%) compared to healthcare workers (12.0%). Healthcare workers perceived the most frequent risk factors for SBS to be poor air quality, an inappropriate level of relative humidity, and inappropriate room temperature, while the least frequently self-perceived risk factors were inappropriate lighting and noise levels. CONCLUSIONS: This study represents a platform for further analyses - the identification of health risk factors with environmental monitoring.

Association between Sick Building Syndrome and Indoor Environmental Quality in Slovenian Hospitals: A Cross-Sectional Study.

Increased exposure times to various health risk factors and the vulnerability of building users might result in significantly higher prevalence rates of sick building syndrome (SBS) in a hospital setting compared to other indoor environments. The purpose of our study was to assess the association between SBS symptoms and measured environmental parameters at a Slovenian general hospital. A combination of a self-assessment study and field measurements was conducted in order to estimate the health risk factors for SBS symptoms among the users of a Slovenian general hospital. The Chi-square test was used to analyse the association between observed health and environmental parameters. The response rate was 67.5%. A total of 12.0% of healthcare workers at hospital wards reported at least six SBS symptoms, 19.0% reported 2-3 SBS symptoms. At the observed hospital wards, the most deviations were recorded for the level of lighting (83.3%), noise level (73.6%), and room temperature (55.3%). A statistically significant association was found between indoor environmental quality and skin-related SBS symptoms (χ2 = 0.009; p = 0.006). This information will be of great value in defining an integral strategy of environmental health activities aimed at healthier indoor environmental quality in hospitals.

User-Centred Healing-Oriented Conditions in the Design of Hospital Environments.

Design approaches towards energy efficient hospitals often result in a deteriorated indoor environmental quality, adverse health and comfort outcomes, and is a public health concern. This research presents an advanced approach to the design of a hospital environment based on a stimulative paradigm of healing to achieve not only healthy but also comforting conditions. A hospital room for severely burn patient was considered as one of the most demanding spaces. The healing environment was designed as a multi-levelled, dynamic process including the characteristics of users, building and systems. The developed integral user-centred cyber-physical system (UCCPS) was tested in a test room and compared to the conventional system. The thermodynamic responses of burn patients, health care worker and visitor were simulated by using modified human body exergy models. In a healing environment, UCCPS enables optimal thermal balance, individually regulated according to the user specifics. For burn patient it creates optimal healing-oriented conditions with the lowest possible human body exergy consumption (hbExC), lower metabolic thermal exergy, lower sweat exhalation, evaporation, lower radiation and convection. For healthcare workers and visitors, thermally comfortable conditions are attained with minimal hbExC and neutral thermal load on their bodies. The information on this is an aid in integral hospital design, especially for future extensive renovations and environmental health actions.