Radon is a naturally occurring radioactive gas that we can find in our homes and indoor workplaces (schools, offices, etc.). Although we have heard only sometimes the word ‘radon’  it is present everywhere in the air.

It is produced by the decay of uranium, which is present in rocks and soils. Radon is harmlessly dispersed in outdoor air, but when trapped in buildings (homes, schools, workplaces) can reach in some cases high concentrations. Some building materials and water represent a secondary sources of radon. If radon is inhaled the radiation produced can damage the lung tissues generating carcinogenic processes.  The risk of contracting lung cancer is proportional to the concentration of radon. Radon is considered the second leading cause of lung cancer after smoking.
In Italy it is estimated that more than 3,000 of 30,000 annual cases of lung cancer are radon related, most of them among smokers and ex-smokers. Radon concentrations are highly variable in time and space; close buildings can have very different concentrations. However, there are areas in Italy with more chances of high concentrations. This fact  doesn’t mean that all the houses in these areas are at risk but at the same time is wrong to think that the houses outside of these areas are all in security.
In Italy, regulations about protection from radon exposure is currently only in force for workplaces, including schools (Legislative Decree no. 230/95). This legislation commits  employers to measure the annual average concentration of radon for certain types of workplaces (underground places) and set a level of action of 500 Bq m-3. Above this value, employers must implement measures to reduce radon exposure of workers. Concerning the houses, in Italy still doesn’t exist a legislation, but there are specific requirements in the new European directive on radiation protection (2013/59/Euratom), which also contains stricter instructions for the workplace safety.
The directive, which has to be implemented in the Italian legislation by the begin of 2018, assumes  that each EU Member State must establish the reference levels for the annual average concentration of radon, for both homes and for workplaces, that do not exceed 300 Bq m-3. In this frame the only way to know the radon concentration is the direct measurement and make a radon test in the houses, in schools or in the workplace.
This operation is simple and cheap, using some appropriate detectors (small size like a clock) in the daily environments for a long period (more than a year). It is also possible to ask the support to ISPRA, ARPA (Regional Agencies for Environmental Protection) or to private companies, making sure that those can guarantee the measurement system quality.  Once you know the value of indoor radon concentration you can make decisions on possible remedial actions, particularly in cases of high concentrations.
There are several ways to reduce the presence of radon depending on the level of concentration and the type of house, with costs  from few to thousands of euros. Radon is a serious health problem but we have solutions to protect our health, that is why it is important to be informed and to measure the concentration within the places in which we live.