[en] Considering that radon and its progeny exposure is proved to be the main cause of lung cancer among nonsmokers and occupation-time at some commercial establishments and workplaces is equal or even bigger then at domiciles and dwelling, present study has been spread to the constructed closed environment and workplaces of commerce and productive sector. The measurements were performed by the Laboratory of Applied Nuclear Physics of UTFPR in 2009 - 2011 when 120 detectors were installed at domiciles and workplaces of Curitiba, Parana St., Brazil. Experimental setup was based at CR-39 detectors that were installed in diffusion chambers protected with filters. In collaboration with CDTN/CNEN it was performed the calibration of CR-39 detectors at the NIRS in Japan. The exposure time was set to be of 100 days. Alpha particle track development was performed using 6.25M sodium hydroxide (NaOH) solution and ethanol (2%) during 14 hours at 70 deg C. The counting was conducted using an optical microscope. Measured ²²²Rn activity levels in dwellings varied between 4.37 Bq/m³ and 320.82 Bq/m³ resulting at an average of 46.94 Bq/m³. Indoor measurements at workplaces presented the variation of radon activity concentration between 3.08 Bq/m³ and 67.50 Bq/m³ resulting at the average of 34.51 Bq/m³. Considering the recommendations of the World Health Organization, UNSCEAR and the International Commission on Radiological Protection (ICRP) concerning the radon-in-air concentration inside the dwellings that can reach 200 Bq/m³ taking into account the occupation-time of 7000 hours/year, obtained results are within normal limits and no mitigation measures have to be performed. (author)