Saeed Ur Rahman

Indoor radon concentration measurement in the dwellings of district Poonch (Azad Kashmir), Pakistan

The present study deals with measurement of indoor radon concentrations in dwellings of the district Poonch of the state of Azad Jammu and Kashmir, Pakistan. In this context, CR-39-based box-type radon detectors were installed in drawing rooms and bedrooms of 80 selected houses and were exposed to indoor radon for 3 months. After exposure, the CR-39 detectors were etched for 9 h in 6 mol NaOH at 70 degrees C and the observed track densities were related to radon concentrations. Measured indoor radon concentrations in the studied area ranged from 27 +/- 6 to 169 +/- 4, 29 +/- 6 to 196 +/- 4 and 31 +/- 5 to 142 +/- 2 Bq m(-3) in the drawing rooms and 74 +/- 5 to 172 +/- 3, 32 +/- 6 to 191 +/- 4 and 27 +/- 5 to 155 +/- 2 Bq m(-3) in bedrooms of the Abbaspur, Hajira and Rawalakot regions of the district Poonch, respectively; whereas weighted average radon concentration ranged from 93 +/- 6 to 159 +/- 4, 33 +/- 5 to 118 +/- 3 and 31 +/- 6 to 155 +/- 5 Bq m(-3) in the dwellings of Abbaspur, Hajira and Rawalakot, respectively. Estimated doses due to the indoor radon ranged from 2.35 +/- 0.15 to 4.00 +/- 0.10, 0.83 +/- 0.08 to 2.98 +/- 0.08 and 0.78 +/- 0.15 to 3.91 +/- 0.13 mSv y(-1) for Abbaspur, Rawalakot and Hajira, respectively. Comparing the current indoor radon results with those of the Health Protection Agency UK and US EPA (i.e. 200 and 148 Bq m(-3)) limits, majority of the houses surveyed in the present study are within the safe limits.

Indoor Radon Survey in 120 Schools Situated in Four Districts of the Punjab Province — Pakistan

An indoor radon survey has been carried in 120 schools situated in four districts of the Punjab province, namely Attock, Chakwal, Jhelum, and Rawalpindi. In each season, a total of 360 CR-39-based radon detectors were installed in the selected schools. After exposure the detectors were etched in 6M NaOH at 80°C solution for 16 h and tracks densities, which are related to the radon concentration, were measured. Indoor radon concentration varied from 18 ± 7 to 168 ± 5 Bq·m-3 with an average value of 52 ± 9 Bq·m-3. High indoor radon concentration values were found in the summer season, whereas lower values were recorded in autumn season. The mean annual radon effective dose equivalent was estimated to be 0.49 mSv per year. Present indoor radon concentration values are higher than that of the world average value of 40 Bq·m-3, but lower than the action level recommended by the ICRP.

Evaluation of excess life time cancer risk from gamma dose rates in Jhelum valley

Abstract Human beings are continuously exposed to the radiations coming from outside and inside their bodies. Outside and inside radiations are coming from ground, building materials, food, air, the universe and even elements within human own bodies. According to UNSCEAR 2000 report, background radiations deliver an average effective dose of 2.4mSv per person worldwide. Sustained exposure from high background radiation levels may pose substantial health threats to general public. In the current study we are presenting the results of ambient outdoor gamma dose rates measured for Jhelum valley of the state of Azad Kashmir. This study has been carried out by using Ludlum micrometer-19 which is an active and portable detector. Effects of different parameters of interest on the measured values of gamma dose rates have been investigated. For the region under investigation, minimum and maximum indoor gamma dose rates were found as 610±4.05μGy·y−1 and 1372±2.7μGy·y−1, respectively, whilst minimum and maximum outdoor gamma dose rates were found as 495±4.49μGy·y−1 and 1296±2.78μGy·y−1, respectively. Overall arithmetic mean (A.M) and geometric mean (G.M) values of gamma dose rates for indoor and outdoor measurements were found as 940±3.26μGy·y−1, 892±3.35μGy·y−1 and 928±3.28μGy·y−1, 880±3.37μGy·y−1 respectively. Excess life time cancer risk (ELCR) for indoor exposure ranges from 1.057×10−3 to 2.377×10−3 with an average value of 1.629×10−3. For outdoor exposure, ELCR varies from 0.352×10−3 to 0.792×10−3 with mean value of 0.543×10−3. Average values of indoor gamma doses were found to be greater than the world population-weighted average for indoor gamma dose rates (780μGy·y−1 or 89nGy h−1).

External dose assessment from the measured radioactivity in soil samples collected from the Islamabad capital territory, Pakistan

It is a well known fact that natural radionuclides are the major contributors towards the gamma ray exposure received by the general public. In this context, soil samples were collected from the Islamabad capital territory and activities due to (226)Ra, (232)Th, (40)K and (137)Cs were measured using gamma ray spectrometry: activities ranged from 41.5-106.2 Bq kg(-1), 4.0-193.8 Bq kg(-1), 325.3-657.4 Bq kg(-1) and 1.6-9.45 Bq kg(-1), respectively. From the measured activities, the external hazard index, internal hazard index, absorbed dose rate and mean annual effective dose were calculated. External and internal hazard indices were calculated as 0.76 and 0.95, respectively. The mean absorbed dose rate was found to be 130.97 nGy h(-1). The mean effective dose was estimated as 0.16 mSv y(-1), which is less than the maximum permissible dose of 1 mSv y(-1).

Monitoring of Indoor Radon Levels Around an Oil Refinery Using CR-39-Based Radon Detectors

Contribution of radon and its decay products towards the total effective dose has been reported to be more than 50% and is a second leading cause of the lung cancer after cigarette smoking. It is an established fact that besides soil and rocks, naturally occurring radio nuclides are also associated with the petroleum extracted from the sedimentary deposits. Therefore, radon measurement around oil refineries is desirable. In this regard, an indoor radon measurement study was carried out in 40 dwellings which were situated in the vicinity of an oil refinery in the Rawalpindi district using CR-39-based radon detectors. For comparison, indoor radon levels were also measured in 40 dwellings situated at a greater distance (>2 km) from the refinery. The maximum measured indoor radon concentration was found to be 190 ± 6 Bq·m−3 whilst the minimum recorded concentration was 12 ± 7 Bq·m−3. The mean radon concentration in the dwellings surveyed was 57 ± 29 Bq·m−3. No significant difference was observed in the average indoor radon levels in the dwellings situated near the oil refinery premises when compared with those further away. From the measured radon concentrations, an annual effective dose was calculated to be 0.9 ± 0.1 mSv which is below the ICRP recommended value.

Assessment of Lung Cancer Risk Using Weighted Average Indoor Radon Levels in Six Districts of the Punjab Province in Pakistan

Year-long measurements of indoor radon concentrations were taken in six districts of the Punjab province, Pakistan, using CR-39-based NRPB radon dosimeters. From the measured indoor radon concentrations, excess lung cancer risk was calculated using the risk model reported in the Biological Effects of Ionising Radiation (BEIR VI) report for the 35—54 and 55—64 year age groups. Using a local occupancy factor, average excess lung cancer risk for the 35—54 y age group residents was found to be 0.66, 0.52 and 0.37 for Gujranwala, Gujrat and Hafizabad districts, respectively. For the Sialkot, Mandibahauddin and Narowal districts it was 0.49, 0.57 and 0.59, respectively. Similarly, for the residents in the 55—64 year age group it was 0.5, 0.40, 0.47, 0.39, 0.46 and 0.46 for Gujranwala, Gujrat, Hafizabad, Sialkot, Mandibahauddin and Narowal districts, respectively. The overall average excess lung cancer risk for the area studied was 0.53.

The Influence of Geology on Indoor Radon Concentrations in Neelum Valley Azad Kashmir, Pakistan

Geology of parent rock controls strongly the soil properties which in turn effect the generation and transportation of radon from its point of production to the surface of earth’s crust. Indoor radon concentrations mainly depend upon uranium and thorium content beneath the earth surface and diffusion of radon from rock and soil fractures, stoma and fissures. This paper presents the results of a survey of indoor radon concentrations in Neelum Valley District. CR-39 detectors were installed in 210 houses covering the entire study area. The detectors were retrieved after exposing to indoor radon for a period of 90 days and then etched in 6 M NaOH at 80°C for 16 h. The observed track densities were converted into the indoor radon concentrations using calibration factor of 2.7 tracks cm−2·h−1 per kBq·m−3. Mean annual effective doses were calculated for each measured value of radon concentration using UNSCEAR 2000 model. Effects of geology, fissures, crevice and cracks on radon levels have also been discussed. Results obtained from this study have been compared with radon concentration action levels given by the World Health Organisation and US Environmental Protection Agency and UK Health Protection Agency.

Classification of rocks radionuclide data using machine learning techniques

The aim of this study is to assess the performance of linear discriminate analysis, support vector machines (SVMs) with linear and radial basis, classification and regression trees and random forest (RF) in the classification of radionuclide data obtained from three different types of rocks. Radionuclide data were obtained for metamorphic, sedimentary and igneous rocks using gamma spectroscopic method. A P-type high-purity germanium detector was used for the radiometric study. For analysis purpose, we have determined activity concentrations of 232Th, 226Ra and 40K radionuclides, published elsewhere (Rafique et al. in Russ Geol Geophys 55:1073–1082, 2014), in different rock samples and built the classification model after pre-processing the data using three times tenfold cross-validation. Using this model, we have classified the new samples into known categories of sedimentary, igneous and metamorphic. The statistics depicts that RF and SVM with radial kernel outperform as compared to other classification methods in terms of error rate, area under the curve and with respect to other performance measures.

A review of radon measurement studies with nuclear track detectors (NTDs) in Azad Kashmir

Inhalation of radon and its progeny are the most important component of public exposure to natural radiations. Many epidemiological studies have established the fact that radon and radon progeny are associated with increased incidence of lung cancer. Beside health concerns, radon is an important consideration in other fields, e.g. hydrological research, detection of geological fault lines, prediction of earthquake, uranium deposits and oil exploration. The importance of the subject compelled many scientists to develop methods for measurement and mitigation of radon. During last decade many studies for measurement of radon and thoron have been conducted in Azad Kashmir. In most studies, the techniques used involve the usage of solid state nuclear track detectors. Building materials, including granite, marbles, gravel aggregates, bricks, sand and soil have been characterized through radon exhalation rate studies. Several research articles have been published, reporting indoor radon measurements in dwellings and at workplaces. Though these studies have provided preliminary information about radon levels in the area, however, data obtained are still unable to convey clear information to readers. This review paper attempts to organize the radon data to provide a clearer understanding and roadmap for radon measurements in Azad Kashmir.

Intercomparison of environmental gamma doses measured with A NaI (Tl) survey meter and thermoluminescent dosimeters (TLDs) in the Poonch division of Azad Kashmir, Pakistan.

This study presents the intercomparison of the outdoor environmental gamma dose rates measured using a NaI (Tl) based survey meter along with thermoluminescent dosimeters (TLDs) and estimation of excess lifetime cancer risk (ELCR), for the inhabitants of Poonch division of the Azad Kashmir, Pakistan. CaF2: Dy (TLD-200) card dosimeters were installed at height of 1 m from ground at fifteen different locations covering the entire Poonch division comprising of three districts. During three distinct two month time periods within the six month study period, all the installed dosimeters were exposed to outdoor environmental gamma radiations, retrieved and read out at Radiation Dosimetry Laboratory, Health Physics Division, PINSTECH laboratory, Islamabad. The ambient outdoor gamma dose rate measurements were also taken with NaI (Tl) based portable radiometric instrument at 1 m above the ground. To estimate the annual gamma doses, NaI (Tl) based survey data were used for one complete year following the deployment of the dosimeters. The mean annual gamma dose rates measured by TLDs and survey meter were found as 1.47±0.10 and 0.862±0.003 mGy/y respectively. Taking into account a 29% outdoor occupancy factor, the annual average effective dose rate for individuals was estimated as 0.298±0.04 and 0.175±0.03 mSv/y by TLDs and survey meter, respectively. For outdoor exposure, the ELCR was calculated from the TLD and survey meter measurements. The environmental outdoor average annual effective dose obtained in present study are less than the estimated world average terrestrial and cosmic gamma ray dose rate of 0.9 mSv/y reported in UNSCEAR 2000. The possible origins of gamma doses in the area and incompatibilities of results obtained from the two different measurement techniques are also discussed.