scholarly journals The influence of air conditioning changes on the effective dose due to radon and its short-lived decay products

Nukleonika ◽  
2016 ◽  
Vol 61 (3) ◽  
pp. 239-244
Author(s):  
Dominik Grządziel ◽  
Krzysztof Kozak ◽  
Jadwiga Mazur ◽  
Bernard Połednik ◽  
Marzenna R. Dudzińska ◽  
...  
Keyword(s):  
Effective Dose ◽  
Air Conditioning ◽  
Indoor Environments ◽  
Radon Progeny ◽  
Inhalation Dose ◽  
Decay Products ◽  
Air Supply ◽  
Industrial Buildings ◽  
The Mean ◽  
The Impact

Abstract Most people spend the majority of their time in indoor environments where the level of harmful pollutants is often significantly higher than outdoors. Radon (222Rn) and its decay products are the example of radioactive pollutants. These radioisotopes are the main source of ionizing radiation in non-industrial buildings. The aim of the study was to determine the impact of air-conditioning system on radon and its progeny concentrations and thus on the effective dose. The measurements were carried out in the auditorium at the Environmental Engineering Faculty (Lublin University of Technology, Poland). Measurements of radon and its progeny (in attached and unattached fractions) as well as measurements of the following indoor air parameters were performed in two air-conditioning (AC) operation modes: AC ON and AC ON/OFF. The air supply rate and air recirculation were taken into consideration. The separation of radon progeny into attached and unattached fractions allowed for determining, respectively, the dose conversion factor (DCF) and the inhalation dose for teachers and students in the auditorium. A considerable increase of the mean radon progeny concentrations from 1.2 Bq/m3 to 5.0 Bq/m3 was observed in the AC ON/OFF mode compared to the AC ON mode. This also resulted in the increase of the inhalation dose from 0.005 mSv/y to 0.016 mSv/y (for 200 h/year). Furthermore, the change of the air recirculation rate from 0% to 80% resulted in a decrease of the mean radon concentration from 30 Bq/m3 to 12 Bq/m3 and the reduction of the mean radon progeny concentration from 1.4 Bq/m3 to 0.8 Bq/m3. This resulted in the reduction of the inhalation dose from 0.006 mSv/y to 0.003 mSv/y.

Optimization of computed tomography urography protocol, 1997 to 2008: Effects on radiation dose

2009 ◽  
Vol 50 (4) ◽  
pp. 446-454 ◽  
Author(s):  
P. Dahlman ◽  
L. Jangland ◽  
M. Segelsjö ◽  
A. Magnusson
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
Effective Dose ◽  
Excretory Urography ◽  
Ct Urography ◽  
Tube Current Modulation ◽  
Current Modulation ◽  
Tube Current ◽  
The Mean ◽  
The Impact

Background: Since computed tomography (CT) urography began to replace excretory urography as the primary imaging technique in uroradiology, the collective radiation dose to the patients has increased. Purpose: To examine the changes in the CT urography protocol for investigating suspected urinary tract malignancy between the years 1997 and 2008, and how these changes have influenced the mean effective dose. Material and Methods: The study was based on 102 patients (mean age 66.1±14.8 years, range 31–89 years; 30 female, 72 male) divided into five groups (groups A–E) corresponding to the time points at which changes were made to the CT urography protocol. The mean effective doses were estimated using the ImPACT CT Patient Dosimetry Calculator. Results: The number of scan phases at CT urography was reduced from four to three in 1999, resulting in a reduction of the mean effective dose from 29.9/22.5 (female [F]/male [M]) mSv (group A) to 26.1/18.9 (F/M) mSv (group B). In 2001, mAs settings were adapted to patient size, and the mean effective dose was reduced to 16.8/12.0 (F/M) mSv (group C). In 2005, scans were performed with a multidetector-row CT equipped with automatic tube current modulation in the x- and y-axis (CARE Dose). The effective mAs was also lowered in the unenhanced and excretory phase, yet the mean effective dose increased to 18.2/13.1 (F/M) mSv (group D), since the effective mAs had to be increased in the corticomedullary phase to maintain image quality. In 2008, as tube current modulation in the x-, y-, and z-axis was introduced (CARE Dose4D), the mean effective dose was reduced to 11.7/8.8 (F/M) mSv (group E). Conclusion: This study shows that the individual mean effective dose to patients undergoing CT urography has decreased by 60%, from 29.9/22.5 (F/M) mSv in 1997 to 11.7/8.8 (F/M) mSv in 2008.

Radon and its decay products in an air-conditioned auditorium in correlation with indoor air parameters

2016 ◽  
Vol 26 (5) ◽  
pp. 621-630 ◽  
Author(s):  
Bernard Polednik ◽  
Krzysztof Kozak ◽  
Jadwiga Mazur ◽  
Marzenna Dudzińska ◽  
Dominik Grządziel
Keyword(s):  
Indoor Air ◽  
Air Conditioning ◽  
Particle Number ◽  
Decay Product ◽  
Significant Negative Correlation ◽  
Particle Mass ◽  
Average Particle ◽  
Air Conditioning System ◽  
Decay Products ◽  
The Impact

The measurements of radon and its attached decay product activity concentrations were carried out in an occupied and unoccupied auditorium during three air-conditioning modes i.e. air-conditioning system switched off (air-conditioning off), air-conditioning system switched off during the night and switched on during the day (air-conditioning on/off) and air-conditioning system switched on (air-conditioning on). Higher average concentrations of radon and its decay products were recorded in the auditorium when the air-conditioning system was switched off. The average particle mass and CO2 concentrations and indoor air thermal parameters were elevated during the air-conditioning on/off mode. A statistically significant ( p < 0.001) positive correlation between the decay product concentrations and the particle number and average particle mass concentrations has been observed in the air-conditioning off mode ( r = 0.55 and r = 0.68) and in the air-conditioning on/off mode ( r = 0.54 and r = 0.62, respectively). A significant negative correlation has been observed between the decay product concentrations and the indoor air temperature and CO2 concentrations in the air-conditioning off mode ( r = −0.86 and r = −0.47, respectively). The obtained results confirmed the impact of the air-conditioning system operation on the decrease of health risks related to the presence of radon and its decay products in air conditioned premises.

scholarly journals Impact Assessment of the ventilation systems on microbiological safety and microclimatic conditions of premises.

2020 ◽  
pp. 49-55
Author(s):  
Tetiana Kryvomaz ◽  
Dmytro Varavin ◽  
Rostyslav Sipakov
Keyword(s):  
Air Conditioning ◽  
Residential Buildings ◽  
Operating Conditions ◽  
International Agencies ◽  
Industrial Buildings ◽  
Key Factor ◽  
Poor Ventilation ◽  
Air Conditioning Systems ◽  
The Impact ◽  
Ventilation Systems

The critical aspects of the impact of microbiological contamination on ventilation and air conditioning systems, the microclimate of the premises, and human health are analyzed. The quantitative and qualitative composition of the microflora of premises depends on their functional purpose, design features, operating conditions, climate, and other factors, among which the method of ventilation is essential. The moisturizers in the air conditioning system are hazardous, which provide bacteria and fungi with water necessary for their life and reproduction. In addition, contaminants accumulated in ventilation systems operate as a substrate for feeding microorganisms. Multi-story administrative, public, and residential buildings, industrial buildings, and other places of mass concentration are areas of increased aerobiological risk of infection. In case of improper operation, air conditioning and ventilation systems can be sources of microorganisms in any room. Transmission of infectious aerosol over long distances occurs in rooms with poor ventilation, and a key factor for the outbreak of infection is the direction of airflows. In the context of the COVID-19 pandemic, organizations and international agencies to control the spread of SARS-CoV-2 indoors recommend limiting the operation of exhaust ventilation and recirculation systems. However, there is still insufficient data to clarify the role of heating, ventilation, and air conditioning systems in spreading infection. Risk assessment and decision-making on the choice of air conditioning systems should be dynamic and based on the scale of the pandemic and the verification of the characteristics of HVAC systems and their effectiveness.

scholarly journals Impact Assessment of the ventilation systems on microbiological safety and microclimatic conditions of premises

2020 ◽  
Vol 35 ◽  
pp. 49-61
Author(s):  
T. Kryvomaz ◽  
D. Varavin ◽  
R. Sipakov ◽  
R. Kuzmishina
Keyword(s):  
Air Conditioning ◽  
Residential Buildings ◽  
Operating Conditions ◽  
International Agencies ◽  
Industrial Buildings ◽  
Key Factor ◽  
Poor Ventilation ◽  
Air Conditioning Systems ◽  
The Impact ◽  
Ventilation Systems

The critical aspects of the impact of microbiological contamination on ventilation and air conditioning systems, the microclimate of the premises, and human health are analyzed. The quantitative and qualitative composition of the microflora of premises depends on their functional purpose, design features, operating conditions, climate, and other factors, among which the method of ventilation is essential. The moisturizers in air conditioning system are hazardous, which provide bacteria and fungi with water necessary for their life and reproduction. In addition, contaminants accumulated in ventilation systems operate as a substrate for feeding microorganisms. Multi-story administrative, public and residential buildings, industrial buildings, and other places of mass concentration are areas of increased aerobiological risk of infection. In case of improper operation, air conditioning and ventilation systems can be sources of microorganisms in any room. Transmission of infectious aerosol over long distances occurs in rooms with poor ventilation, and a key factor for the outbreak of infection is the direction of airflows. In the context of the COVID-19 pandemic, organizations and international agencies to control the spread of SARS-CoV-2 indoors recommend limiting the operation of exhaust ventilation and recirculation systems. However, there is still insufficient data to clarify the role of heating, ventilation, and air conditioning systems in spreading infection. Risk assessment and decision-making on the choice of air conditioning systems should be dynamic and based on the scale of the pandemic and the verification of the characteristics of HVAC systems and their effectiveness.

scholarly journals The distribution of air temperature and velocity in the selected boiler room

2018 ◽  
Vol 44 ◽  
pp. 00020 ◽  
Author(s):  
Robert Cichowicz ◽  
Artur Stelęgowski
Keyword(s):  
Air Temperature ◽  
Thermal Environment ◽  
Physical Factors ◽  
Limit Values ◽  
Air Supply ◽  
Industrial Buildings ◽  
Boiler Room ◽  
Environment Parameters ◽  
The Impact

The crucial impact on the indoor air quality in technological rooms, including boiler plant buildings, is made by operation of technological devices and ventilation systems. Therefore, the distribution of air temperature and velocity in these rooms mainly depends on location and heat gains generated by combustion devices, as well as emplacement of air supply and air exhaust elements. The temperature and airflow volume of supplied air is also an issue, because the indoor environment parameters are formed by the flow of air in the working area. Determination of the impact of physical factors on the thermal environment in a room is possible using an analysis of the air temperature and velocity. This issue is vital in terms of necessity to maintain the adequate heat conditions in the working area. Therefore, basing on the experimental measurements and numerical calculations (made in DesignBuilder software), the distribution of air temperature and velocity was analyzed in the selected industrial boiler room, located in the Lodz city, in Poland. The results obtained were compared with the recommended and limit values in the industrial buildings.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Sound Production Treatment for Acquired Apraxia of Speech: An Examination of Dosage in Relation to Probe Performance

2020 ◽  
pp. 1-16
Author(s):  
Julie L. Wambaugh ◽  
Lydia Kallhoff ◽  
Christina Nessler
Keyword(s):  
Retrospective Analysis ◽  
Sound Production ◽  
Apraxia Of Speech ◽  
Practice Schedule ◽  
Practice Schedules ◽  
Baseline Performance ◽  
The Mean ◽  
Number Of Treatment ◽  
The Impact

Purpose This study was designed to examine the association of dosage and effects of Sound Production Treatment (SPT) for acquired apraxia of speech. Method Treatment logs and probe data from 20 speakers with apraxia of speech and aphasia were submitted to a retrospective analysis. The number of treatment sessions and teaching episodes was examined relative to (a) change in articulation accuracy above baseline performance, (b) mastery of production, and (c) maintenance. The impact of practice schedule (SPT-Blocked vs. SPT-Random) was also examined. Results The average number of treatment sessions conducted prior to change was 5.4 for SPT-Blocked and 3.9 for SPT-Random. The mean number of teaching episodes preceding change was 334 for SPT-Blocked and 179 for SPT-Random. Mastery occurred within an average of 13.7 sessions (1,252 teaching episodes) and 12.4 sessions (1,082 teaching episodes) for SPT-Blocked and SPT-Random, respectively. Comparisons of dosage metric values across practice schedules did not reveal substantial differences. Significant negative correlations were found between follow-up probe performance and the dosage metrics. Conclusions Only a few treatment sessions were needed to achieve initial positive changes in articulation, with mastery occurring within 12–14 sessions for the majority of participants. Earlier occurrence of change or mastery was associated with better follow-up performance. Supplemental Material https://doi.org/10.23641/asha.12592190

Predicting Daily Maintenance Dose of Fluindione, an Oral Anticoagulant Drug

1996 ◽  
Vol 75 (05) ◽  
pp. 731-733 ◽  
Author(s):  
V Cazaux ◽  
B Gauthier ◽  
A Elias ◽  
D Lefebvre ◽  
J Tredez ◽  
...  
Keyword(s):  
Effective Dose ◽  
Maintenance Dose ◽  
Successive Approximations ◽  
Hemorrhagic Complication ◽  
Simple Method ◽  
Individual Variations ◽  
Anticoagulant Drug ◽  
The Mean ◽  
Mean Time ◽  
Daily Maintenance Dose

SummaryDue to large inter-individual variations, the dose of vitamin K antagonist required to target the desired hypocoagulability is hardly predictible for a given patient, and the time needed to reach therapeutic equilibrium may be excessively long. This work reports on a simple method for predicting the daily maintenance dose of fluindione after the third intake. In a first step, 37 patients were delivered 20 mg of fluindione once a day, at 6 p.m. for 3 consecutive days. On the morning of the 4th day an INR was performed. During the following days the dose was adjusted to target an INR between 2 and 3. There was a good correlation (r = 0.83, p<0.001) between the INR performed on the morning of day 4 and the daily maintenance dose determined later by successive approximations. This allowed us to write a decisional algorithm to predict the effective maintenance dose of fluindione from the INR performed on day 4. The usefulness and the safety of this approach was tested in a second prospective study on 46 patients receiving fluindione according to the same initial scheme. The predicted dose was compared to the effective dose soon after having reached the equilibrium, then 30 and 90 days after. To within 5 mg (one quarter of a tablet), the predicted dose was the effective dose in 98%, 86% and 81% of the patients at the 3 times respectively. The mean time needed to reach the therapeutic equilibrium was reduced from 13 days in the first study to 6 days in the second study. No hemorrhagic complication occurred. Thus the strategy formerly developed to predict the daily maintenance dose of warfarin from the prothrombin time ratio or the thrombotest performed 3 days after starting the treatment may also be applied to fluindione and the INR measurement.

Impact of changing rainfall conditions on surface and groundwater resources in an experimental watershed in Greece

2013 ◽  
Vol 12 (2) ◽  
pp. 119-125
Keyword(s):  
Groundwater Resources ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Regime ◽  
Winter Rainfall ◽  
Rainfall Depth ◽  
Rainfall Volume ◽  
The Mean ◽  
Groundwater Reserves ◽  
The Impact

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.

Radiation exposure of the staff at the therapeutic and diagnostic nuclear medicine department

2008 ◽  
Vol 47 (04) ◽  
pp. 175-177 ◽  
Author(s):  
J. Dolezal
Keyword(s):  
Nuclear Medicine ◽  
Radiation Exposure ◽  
Effective Dose ◽  
Radiation Protection ◽  
Annual Effective Dose ◽  
Protection Measures ◽  
Professional Groups ◽  
Personal Dosimetry ◽  
The Mean ◽  
Administered Activity

SummaryAim: To assess a radiation exposure and the quality of radiation protection concerning a nuclear medicine staff at our department as a six-year retrospective study. Therapeutic radionuclides such as 131I, 153Sm, 186Re, 32P, 90Y and diagnostic ones as a 99mTc, 201Tl, 67Ga, 111In were used. Material, method: The effective dose was evaluated in the period of 2001–2006 for nuclear medicine physicians (n = 5), technologists (n = 9) and radiopharmacists (n = 2). A personnel film dosimeter and thermoluminescent ring dosimeter for measuring (1-month periods) the personal dose equivalent Hp(10) and Hp(0,07) were used by nuclear medicine workers. The wearing of dosimeters was obligatory within the framework of a nationwide service for personal dosimetry. The total administered activity of all radionuclides during these six years at our department was 17,779 GBq (99mTc 14 708 GBq, 131I 2490 GBq, others 581 GBq). The administered activity of 99mTc was similar, but the administered activity of 131I in 2006 increased by 200%, as compared with the year 2001. Results: The mean and one standard deviation (SD) of the personal annual effective dose (mSv) for nuclear medicine physicians was 1.9 ± 0.6, 1.8 ± 0.8, 1.2 ± 0.8, 1.4 ± 0.8, 1.3 ± 0.6, 0.8 ± 0.4 and for nuclear medicine technologists was 1.9 ± 0.8, 1.7 ± 1.4, 1.0 ± 1.0, 1.1 ± 1.2, 0.9 ± 0.4 and 0.7 ± 0.2 in 2001, 2002, 2003, 2004, 2005 and 2006, respectively. The mean (n = 2, estimate of SD makes little sense) of the personal annual effective dose (mSv) for radiopharmacists was 3.2, 1.8, 0.6, 1.3, 0.6 and 0.3. Although the administered activity of 131I increased, the mean personal effective dose per year decreased during the six years. Conclusion: In all three professional groups of nuclear medicine workers a decreasing radiation exposure was found, although the administered activity of 131I increased during this six-year period. Our observations suggest successful radiation protection measures at our department.

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