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Several epidemiological studies conducted on thousands of underground miners suggest that long- term exposure to high radon concentration can increase the risk of lung cancer. Keeping in view the importance of the subject, numerous studies throughout the world have been carried out to measure indoor radon concentration and its resulting doses at occupational and non-occupational sites. The purpose of the current study was to measure indoor radon concentration and its resulting doses received by the students of Azad Kashmir government schools. For this purpose, CR-39 radon detectors were installed in 80 carefully selected schools. The detectors were placed at a height of 3-5 ft. (depending upon average height of students in particular class) from the ground. After exposure of 90 d detectors were etched for 9 h in 6 M NaOH at 70°C and the observed track densities were related to radon concentrations. The measured indoor radon concentration ranged from 22 ± 9 to 228 ± 3 Bq m(-3) with a mean value of 78 ± 5 Bq m(-3). Based on the measured indoor radon data, the annual effective doses were found to vary from 0.55 ± 0.04 to 0.71 ± 0.03 mSv y(-1). The overall mean effective dose for the studied area was found to be 0.63 ± 0.04 mSv y(-1). Reported values for radon concentrations and corresponding doses are lower than ICRP recommended limits for workplaces.

We present results of Multifractal Detrended Fluctuation Analysis (MF-DFA) of soil radon (222Rn) and thoron (220Rn) time series to examine the scaling and multifractal features. Data consists of 15,692 measurements taken each over forty-minute interval. RTM 1688–2, 222Rn/220Rn electronic device has been used for measurement purposes. Seasonal periodicities have been removed from the data and MF-DFA was employed on de-seasonalized data. Original 222Rn and 220Rn time series have been converted into surrogated and shuffled time series. MF-DFA has also been applied to the surrogated and shuffled series to examine the multifractality nature. Results of the study show that Orig 222 Rn , Surr 222 Rn and Orig 220 Rn , Surr 220 Rn time series are long-range positively correlated and an increase or decrease in either of radionuclide concentrations will be followed by another increase or decrease of concentrations in future measurements. The Shuff 220 Rn time series has an independent or short-range dependent structure called white noise and the shuffled time series exhibit a very weak multifractality. [ABSTRACT FROM AUTHOR]

Owing to the potential health threats due to sustained exposure from the radioactivity born radon and thoron gases and their applications, especially radon as earthquake precursor, the complex dynamic relationship between either of the radioactive gas with meteorological parameters has become the focus of research area. Several studies have reported that meteorological factors greatly influence the radon and thoron radioactive gases. In present study we investigated the scaling behavior of cross-correlations between simultaneously observed Radon and Thoron time series with temperature, pressure, and humidity time series. Data for radon, thoron and other meteorological parameters were obtained using RTM 1688-2 active detector from March 2017 to April 2018, with the total number of data points in each time series greater then fifteen thousands. Data obtained was investigated by Multi-fractal Detrended Cross-correlation Analysis (MFDXA) method through detrended covariance function. The computed cross-correlations were also investigated for multifractal or monofractal nature as well as for the degree of multifractality. Results of the study show that all correlations exhibit long range power law behavior. A nonlinear variation of scaling exponent ′ h x y (q) ′ vs 'q' (order of fluctuation) shows multifractal nature of cross-correlations with h x y (q) > 0. 5 for all correlations. Which means that all correlations are persistently positive correlated. The degree of multifractality was estimated by the width of singularity spectrum Δ α. The results show that for each of the correlations width of singularity spectrum is nonzero confirming the multifractal nature of computed correlations. Finally, for Radon/Thoron correlation with temperature and humidity the width of singularity spectrum i.e., Δ α > 0. 5 shows high multifractality when compared with Radon/Thoron vs pressure correlation with Δ α < 0. 5 showing low multifractality. [ABSTRACT FROM AUTHOR]

This paper investigates the complexity of soil radon time series (RTS) recorded from March 2017 to April 2018 in Pakistan via RTM 1688-2 monitor, in direct linkage to parallel series of temperature, relative humidity, and pressure. Several complexity measures are employed. The normalized Lempel Ziv Complexity (LZC) of the complete RTS is 0.30 and 0.14, 0.22, and 0.14 for the complete time series of temperature, relative humidity and pressure respectively. LZC ranges between 0.3 and 0.5 for RTS and between 0.1 and 0.3 for temperature (T), relative humidity (RH) and pressure (P). Hurst exponent (HE) values via rescaled range (R/S) analysis show an inverse relationship with LZC. HE ranges between 0.60 ≤ HE ≤ 0.98 for RTS, 0.60 ≤ HE ≤ 0.92 for T series, 0.61 ≤ HE ≤ 0.93 for RH series, and 0.87 ≤ HE ≤ 0.98 for P series. Permutation Entropy (PE) is 1.7809 for complete RTS with a minimum of 1.7668 in August 2018. Highest value of Sample Entropy (SE) is 1.3716 for February 2018. The highest symbolic Normalized Corrected Shannon Entropy (NCSE) value is found in January 2018 with a value of 0.7864. Finally, the Fractal Dimensions varied significantly for calculation with the Sevcik's, Higuchi's and Katz's methods. Common dates of below threshold areas are reported. The different aspects of the derived results are discussed. [Display omitted] • Complexity, Hurst exponents and fractal dimensions of soil radon (RTS) in Pakistan. • Normalized LZC are between 0.3 and 0.5 and Hurst exponents between 0.60 ≤ HE ≤ 0.9. HE show inverse relationship with LZC. • Minimum Permutation Entropy was 1.7668 on August 2018, maximum Sample Entropy was 1.3716 on February 2018. • Common dates of minimum fractal dimensions via Sevcik's, Higuchi's and Katz's methods are reported. [ABSTRACT FROM AUTHOR]