Study type	Target population	Main purpose of the study	Method of radon dosimetry	Major finding/conclusions
Cohort studies	Miners/occupational exposure	Determine the risk of lung cancer morality in exposed miners	Radiation exposure was estimated using job-exposure matrix (JEM) which provides exposure values for potential alpha energy from radon and its progeny in working level months (WLM)	High levels of radon exposure were associated with increased cancer risk.
Case control studies	The public/residential exposure	Determine the risk of lung cancer in residential setting	Year-long residential radon levels were measured by a-track detectors and were used to estimate exposure in the 25 years prior to the index date.	Most studies reported small insignificant association between residential radon exposure and lung cancer, some studies found negative association.
Pooled analysis of the cohort studies on miners	Obtain summary estimates of the risk of lung cancer in radon-exposed miners using large sample size.	A summary of the WLM exposure was obtained for the total subjects using reported exposure levels in the individual studies.	A summary of the WLM exposure was obtained for the total subjects using reported exposure levels in the individual studies.	A consistent linear relationship for cumulative radon progeny and lung cancer was observed in the range of miner exposures
Combined analysis of case-control studies	The general public/residential exposure in Europe and North America	Obtain accurate estimates of lung cancer risk from residential radon exposure by reducing incertainity in radon dosimetry	Available radon measurements form individual studies were used to estimate radon exposure for the total individuals in all homes occupied over the past 5 - 30 years.	A significant increase in risk of lung cancer was associated with increased radon exposures with seemingly linear dose-response relationship.