Knowledge

What is radon

A natural radioactive gas from the decay of uranium in soil and rock. Colourless, odourless and tasteless: hard to detect without specialised equipment.

Introduction

The gas you cannot see

Radon can seep through the ground and build up in enclosed spaces such as homes, offices and workplaces, posing a health risk.

Health

Why is it dangerous?

Prolonged exposure to radon can cause serious health problems and is the leading cause of lung cancer in non-smokers.

According to the WHO, the proportion of lung cancer cases linked to radon ranges from 3% to 14% of the total.

As it is an invisible gas, the only way to know whether it is present at dangerous levels is through proper measurement. There is no known threshold below which there is no risk: even very low concentrations imply a small increase.

Location

Where is it most common?

Radon is most often found in buildings located in areas with high concentrations of the gas in the ground.

In Spain, the regulations identify “priority-action zones” where it is more likely to exceed the limits. These include the ground and basement floors of certain municipalities, and it is especially common in regions with radium-rich, highly fractured soils.

Check the risk in your area→

Limits

Regulations and established limits

The reference level in Spain is 300 Bq/m³ of annual average radon concentration in indoor air, in line with the recommendations of the European Union and the World Health Organization.

Current regulations are based on European directives and national laws governing both measurement and protective actions.

Applicable regulations
  • Royal Decree 1029/2022, of 20 December, approving the Regulation on health protection against the risks arising from exposure to ionising radiation.
  • Royal Decree 732/2019, of 20 December, amending the Spanish Building Code (Annex II, Section HS06, protection against radon exposure).
  • CSN Safety Guide 11.4 (December 2012): methodology for assessing radon exposure in workplaces.
  • ISO 11665-4:2012: measurement of radioactivity in the environment (air, radon-222; integrated measurement method using passive sampling).
  • CTE DB-HS6: Basic Document HS Healthiness, section HS 6, protection against radon exposure.

Measurement

How is radon measured?

Measurement is carried out with specialised devices that measure the concentration of the gas in the air. For accurate results, a long-term measurement (at least 3 months) is recommended.

In underground workplaces such as tunnels or mines, 4 measurements of 3 months each are taken to cover a full year.

Action

What to do if levels are high?

If high radon levels are detected, the concentration must be reduced. Common solutions include improving building ventilation, sealing cracks and gaps in floors and walls, or installing depressurisation systems that prevent radon from entering.

For companies, it is crucial to have a prevention plan to protect employees' health.

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