INVESTIGATION OF INDOOR RADON LEVELS IN SELECTED DWELLINGS OF LAGOS AND OGUN STATES, SOUTHWESTERN NIGERIA

Abstract

In this work, radon level in selected dwellings of Lagos and Ogun states, southwestern Nigeria was investigated using Solid State nuclear Track Detectors, CR-39 (Poly Allyl Di-Glycol). The closed detector technique was employed. Seventy (70) 6.25 cm2 sized detectors (out of which fifty-nine were recovered) purchased from Track Analysis Systems Limited (TASL) were distributed to homes randomly within four Local Government Areas in Lagos and Ogun states for between three to four months after which chemical etching and counting was carried out. Concentration values ranged from 5.06 Bq/m3 to 254.69 Bq/m3. The average radon concentrations measured in Lagos and Ogun states are 43.48 ± 7.70 Bq/m3 and 34.23 ± 9.56 Bq/m3 respectively. About 42% of the detectors measured radon levels below 15 Bq/m3 with the average radon concentration across the selected dwellings being 38.48 ± 6.24 Bq/m3 (1.04 ± 0.17 pCi/L). The range 0-15 Bq/m3 contained the highest number of detectors for all four factors (region, height, apartment type and room type) considered in analyzing the distribution of radon concentration in this study. An annual effective dose rate of 1.10 mSv/y was determined for selected dwellings in Lagos while in Ogun, a similar dose rate of 1.22 mSv/y was determined. Comparing with recommended limits of EPA (148 Bq/m3), WHO (100-300 Bq/m3) and ICRP (200-600 Bq/m3), no potential hazards in the region investigated in this study.