Measurement of indoor radon concentration levels in Islamabad, Pakistan

Radiological risk estimation from indoor radon, thoron, and their progeny concentrations using nuclear track detectors

In this paper, we report the results of seasonal variations of indoor radon and thoron concentrations, equilibrium factors for gas progeny, and radiological risks to dwellers in the hilly area of Guwahati City, Assam, India. Twin-cup dosemeters with LR-115 (II) nuclear track detectors were used in this study. The findings show that values vary significantly, with winter having the highest values and summer having the lowest, with spring and autumn having moderate values. In winter, radon concentrations range from 61.6 ± 11.2 Bq m^-3 (Mud) to 115.3 ± 34.3 Bq m^-3 (AT), with geometric mean values of 69.2 ± 13.8 Bq m^-3 and 109.4 ± 27.9 Bq m^-3, and in summer, they range from 21.1 ± 5.9 Bq m^-3 (Mud) to 28.4 ± 8.3 Bq m^-3 (AT), with geometric mean values of 22.7 ± 6.3 Bq m^-3 and 26.1 ± 7.1 Bq m^-3, whereas thoron concentrations range from 13.1 ± 5.1 Bq m^-3 (Mud) to 58.8 ± 12.6 Bq m^-3 (AT), with geometric mean values of 27.6 ± 7.0 Bq m^-3 and 52.9 ± 10.1 Bq m^-3 in winter, respectively, and in summer, from 8.8 ± 2.3 Bq m^-3 (Mud) to 13.0 ± 5.5 Bq m^-3 (Mud), with a geometric mean value of 1.87 ± 1.29 Bq m^-3. Radon and thoron progeny levels are reported to vary from 4.1 ± 0.3 mWL (Mud) to 15.1 ± 4.3 mWL (AT) and 2.6 ± 0.9 mWL (Mud) to 14.3 ± 4.2 mWL (AT) in winter and from 1.5 ± 0.7 mWL (AT) to 3.0 ± 2.5 mWL (Mud) and 0.9 ± 0.3 mWL (AT) to 2.7 ± 0.5 mWL (Mud) in summer, respectively. The equilibrium factors for radon and its progeny have been reported to range from 0.23 ± 0.1 (Mud) to 0.51 ± 0.3 (AT) in winter, whereas from 0.23 ± 0.1 (AT) to 0.48 ± 0.4 (Mud) in summer, respectively. The equilibrium factors for thoron and its progeny have been estimated in the range of 0.02 ± 0.01 (Mud) to 0.09 ± 0.06 (AT) in winter, whereas 0.02 ± 0.02 (AT) to 0.07 ± 0.05 (Mud) in summer, respectively. The inhalation dose rates differed from house to house, having values in the range of 1.2 ± 0.2 mSv year^-1 (Mud) to 4.6 ± 1.3 mSv year^-1 (AT) in winter, whereas 0.5 ± 0.3 mSv year^-1 (AT) to 0.9 ± 0.5 mSv year^-1 (Mud) in summer, respectively. The effective doses (EDs) due to the exposure of radon and thoron in the study area have been found to range from 2.5 ± 0.3 mSv (Mud) to 9.1 ± 2.7 mSv (AT) in winter and 0.9 ± 0.4 mSv (AT) to 1.8 ± 1.3 mSv (Mud) in summer, respectively. The levels of radon and thoron in similar types of construction were found to be significantly different from one house to another. The estimated radon and thoron concentrations in the houses of that region during winter are found to be substantially higher than the global averages as reported by UNSCEAR.

Radiation Health Hazard and Risks Assessment Among Greenhouse Farmers in Egypt, seasonal Study

OBJECTIVES

Greenhouses have been rapidly developing in Egypt in the recent years so as to overcome the problem of water shortage required for agriculture because agriculture in protected houses provides about 20-40% of the water consumption from agriculture in open lands. Greenhouses are widely used to cultivate different kinds of plants. Greenhouses are considered spacious, enclosed areas, in close contact with airtight and soil. They have been the main radon source for a long time. Radon and its progeny are released and trapped in the vacant space of greenhouses, causing health hazards for the farmers who work in them. Taking this into consideration, seasonal radon concentration levels have been monitored and measured in 8 greenhouses located at the city of Alexandria and Rosetta, Egypt.

MATERIALS AND METHODS

Passive closed-and-open can techniques are mainly used to calculate these concentrations. Each can has an attached CR-39 polymeric nuclear track detector as a detector material. For a period of one year inside the chosen greenhouses, the dosimeter has been exposed to the local for four seasons, 3 months each.

RESULTS

The average annual radon concentration in those greenhouses varies between the lowest radon concentration value of 310 ± 86 Bqm^-3 in the glass greenhouse in Alexandria, and the highest concentration value of 543 ± 88 Bqm^-3in the plastic greenhouses in Rosetta, with a total average annual value of 476 ± 68 Bqm^-3 . A remarkable variation in the seasonal radon concentrations in the greenhouses is observed. Also, in the research at hand, the radon radiation dose received by a farmer working in the greenhouses is calculated according to the ICRP (ICRP, 1993).The occupants' greenhouse exposure rate varies from 1.38 mJ h m^-3 (0.39 WLM) in the plastic greenhouses to 2.42 mJ h m^-3 (0.683 WLM) in the glass ones, with an average value of 1.68 mJ h m^-3 (0.55 WLM) during that year. The workers' estimated effective dose per annum ranges between 1.94 mSv and 3.39 mSv with an average dose of 2.73 mSv.

CONCLUSION

In all the examined greenhouses in the Egyptian cities of Alexandria and Rosetta, the estimated effective dose per year is in the lower limit range of the action level (3-10 mSv) recommended for greenhouse workers by the ICRP (ICRP,1993), and it does not exceed the ICRP's upper limit. If the farmers work for a long number of years in the greenhouses, the occupational exposure to radiation doses due to radon concentration must be taken into consideration.

Short-Term Measurement of Indoor Radon Concentration in Northern Croatia

(1) Background: Radon concentrations in the environment are generally very low. However, radon concentrations can be high indoors and can cause some serious health issues. The main source of indoor radon (homes, buildings and other residential objects) can be soil under the house, while other sources can be construction materials, groundwater and natural gas. Radon accumulates mainly in the lower levels of the buildings (especially low-ventilated underground levels and basements). (2) Methods: in this paper, we have measured the indoor radon concentrations at 15 locations in various objects (basements and ground floor/1st floor rooms) in the area of northern Croatia. (3) Results: the results show a higher concentration of radon in the basement area in comparison to values measured in the ground floor and first-floor rooms. The arithmetic mean (AM) and geometric mean (GM) of basement rooms were 70.9 ± 38.8 Bq/m3 and 61.2 ± 2.2 Bq/m3 compared to ground floor and first-floor rooms 42.5 ± 30.8 Bq/m3 and 32.8 ± 2.9 Bq/m3, respectively. (4) Conclusions: results obtained (AM and GM values) are within the maximal allowed values (300 Bq/m3) according to the Euroatom Directive. However, there are periods when maximum radon concentration exceeds 300 Bq/m3. Indoor radon concentrations vary with the occupancy of the rooms and it is evident that the ventilation has significant effect on the reduction of concentration.

Simultaneous measurements of radon and thoron, and their progeny levels in dwellings on anticlinal structures of Assam, India

Radon and thoron, and their progeny concentrations along with equilibrium factors for gas progeny and radiological risks to the residents have been measured in dwellings of Digboi and Mashimpur areas located on anticlines during the winter season. In this present investigation, twin-cup dosemeters fitted with LR-115 (II) nuclear detectors have been employed. The present work has shown that there exist considerable house-to-house variations in values with maximum values in mud houses and minimum values in assam type (AT) houses. It has been found that mean (and geometric standard deviations (GSD)) radon concentrations are 83.8 (1.3), 113.5 (1.1) and 157.2 (1.2) Bq m(-3) in AT, reinforced cement concrete (RCC) and mud houses in Digboi area and 63.0 (1.1), 87.1 (1.4) and 182.1 (1.2) Bq m(-3) in AT, RCC and mud houses in Mashimpur area, respectively. The overall mean radon concentrations in Digboi and Mashimpur are estimated to be 114.4 (1.4) and 100.0 (1.7) Bq m(-3). The mean radon concentrations are found to be less than the lower reference level of 200 Bq m(-3) of the International Commission on Radiological Protection (ICRP 2007). The thoron concentrations in Digboi area are estimated to be 31.1 (1.3), 50.8 (1.4) and 67.0 (1.6) Bq m(-3) in AT, RCC and mud houses, respectively, whereas in Mashimpur area, the thoron concentrations are estimated to be 26.4 (1.3), 44.4 (1.3) and 77.7 (1.3) Bq m(-3) in AT, RCC and mud houses, respectively. The mean annual effective doses in Digboi area are found to be 1.9 (1.3), 2.7 (1.2) and 4.1 (1.4) mSv y(-1) in AT, RCC and mud houses, respectively, while in the case of Mashimpur area, the mean annual effective doses are found to be 1.5 (1.4), 2.2 (1.2) and 4.9 (1.3) mSv y(-1) in AT, RCC and mud houses, respectively. Nevertheless, the obtained results are much lower than the upper reference level of 10 mSv (ICRP 2007).

Radioactivity in the indoor building environment in Serbia

Measurement of activity concentrations of radionuclides in building materials and radon in indoor space is important in the assessment of population exposures, as most individuals spend 80 % of their time indoors. This paper presents the results of activity concentration measurements of: radon emanated from the soil, radionuclides (226)Ra, (232)Th and (40)K in the soil, indoor radon in the city of Novi Sad (the capital city of Vojvodina) using charcoal canisters and indoor radon in the Vojvodina region using alpha-track detectors and the radioactivity of some building materials. Influences of floor level, space under the rooms, boarding, and the heating system on indoor radon accumulation in the Vojvodina province, situated in the northern part of Serbia, are also presented in this paper. The total effective dose and the activity concentration index are calculated applying the dose criteria recommended by the European Union for building materials.

Measurement of indoor radon concentration and assessment of doses in different districts of Alexandria city, Egypt

The main objective of this study is to assess the health hazard due to the indoor radon. Measurement studies have been carried out in 56 dwellings belonging to 14 residential areas in Alexandria city, Egypt. Results are obtained using the LR-115 (Type II) alpha track detector in "closed-can" geometry. The dosimeters were installed in bedroom, living room, and the kitchens of each house. For intercomparison purpose, dosimeters are installed in basements, ground floor, and first floor. Measured indoor radon concentrations were found to vary from 15 to 132 Bq m(-3). The average radon concentrations in living room, bedrooms, and kitchen in basements were found to vary from to be 39 ± 10, 63 ± 15 and 81 ± 25 Bq m(-3), respectively. In living room, bedrooms, and kitchen, on ground floor, the average radon concentrations were found to be 35 ± 9, 44 ± 6 and 56 ± 10 Bq m(-3), whereas on first floor, the average values are 29 ± 8, 34 ± 7 and 45 ± 8 Bq m(-3), respectively. The overall mean radon concentration in all surveyed districts has been found to be 44 ± 16 Bq m(-3). The mean annual estimated effective dose received by the residents of the studied area is estimated to be 0.75 mSv. The obtained results are compared with the indoor radon levels prescribed by the International Commission on Radiation Protection and are found to be less than the action level recommended.

Health assessment of natural radioactivity and radon exhalation rate in granites used as building materials in Lebanon

Measurements of specific activities (Bq kg(-1)) of gamma-emissions from radioactive nuclides, (238)U, (226)Ra, (214)Bi, (232)Th, (212)Pb and (40)K, contained in 28 granite types, used as building materials in indoors in Lebanon, were performed on the powdered granites. The concentration of the nuclides, (226)Ra, (232)Th and (40)K, in the granites varied from below detection level (BDL) to 494 Bq kg(-1), BDL to 157.2 Bq kg(-1) and BDL to 1776 Bq kg(-1), respectively. (226)Ra concentration equivalents, C(Raeq), were obtained and ranged between 37 and 591 Bq kg(-1), with certain values above the allowed limit of 370 Bq kg(-1). Calculated annual gamma-absorbed dose in air, D(aR), varied from 17.7 to 274.5 (nGy h(-1)). Annual effective dose, E (mSv y(-1)), of gamma radiations related to the studied granites and absorbed by the inhabitants was evaluated. E (mSv y(-1)) ranged from 0.09 to 1.35 mSv y(-1). Some granite types produced E above the allowed limit of 1 mSv y(-1) set by ICRP. Values of (222)Rn mass exhalation rate, E(M) (mBq kg(-1)h(-1))(,) in granite powder were obtained using the CR-39 detector technique. Diffusion factors, f, in 23 granite types were calculated with f ranging between (0.1 ± 0.02)×10(-2) and (6.6 ± 1.01)×10(-2).

Assessment of the dose received by students and staff in schools in the Rawalpindi region of Pakistan due to indoor radon

Studies concerning measurements of indoor radon levels were carried out in 60 schools in the Rawalpindi region of Pakistan. In each school, six CR-39 based NRPB type radon detectors were installed and exposed to the indoor radon in two cycles (each of six months' duration). After exposure, the detectors were removed, etched in 6 M NaOH for 16 h at 80 degrees C, and the tracks were counted under an optical microscope. The measured track densities were then related to radon concentrations, from which the radiation doses were calculated. The observed radon concentrations varied from 15 to 140 Bq m(-3), with an average activity concentration of 42.75 +/- 9.28 Bq m(-3). The mean annual radon effective dose equivalent was found to be 0.40 +/- 0.09 mSv using an occupancy factor of 8 h day(-1). Our results show that the indoor radon concentrations in the schools surveyed are within the permissible limits.