Radon is found to be the second most common reason for lung cancer (after smoking). Since radon can easily be trapped inside buildings, indoor radon concentrations can increase to many times that of outdoor levels. When radon gas decays, it emits radioactive radiation in the form of an alpha particle/waves.
To address worsen outdoor air quality, frequency of filter cleaning in 5-star hotels has been increased in the past from bi-weekly/monthly to almost daily/weekly. Think about the cost implication and solid waste generation on the amount of filters needed to be treated or replaced more frequently.