Hong Kong 's natural background radiation comes from local granite . Rock is used in construction for local buildings . Radiation was monitored by community - based environmental monitoring group . `` What Safecast is doing provides a context for people to understand radiation , '' said Franken , producing two photos he planned to contribute to an online photography magazine . Levels of radiation in air are not harmful .
Hong Kong 's natural background radiation comes from local granite . Rock is used in construction for local buildings . Radiation was monitored by community - based environmental monitoring group . Levels of radiation in air are not harmful .