Radon in workplaces and commercial premises — who is liable

The reference level of 200 Bq/m³ applies to workplaces too, but both the method and the responsible party differ from a dwelling. In a workplace it is the employer who is responsible for keeping employees' exposure below the reference level, and the Swedish Radiation Safety Authority (Strålsäkerhetsmyndigheten, SSM) is the supervisory authority — not the municipal environmental committee, which supervises the dwellings.

In a mixed portfolio with shops or offices on the ground floor, that means the same building falls under two regimes with two responsible parties.

The differences that matter

	Dwelling	Workplace
Responsible	The property owner	The employer
Supervision	Municipal environmental committee	Swedish Radiation Safety Authority
Basis of assessment	Annual average for the space	Radon level during working hours
Method	SSM's method description for dwellings	SSM's method description for workplaces

The third row is what produces different answers for the same room. Premises used on weekdays during the day can have an annual average above 200 Bq/m³ and still an exposure below the reference level during working hours, because the ventilation runs in the daytime — or the reverse, if the ventilation stops at night and the level builds up before morning.

The notification duty that does not exist for dwellings

Here the workplace rules diverge on a point that is often missed. If the annual average during working hours exceeds 200 Bq/m³, the employer must take measures to reduce it. If those measures do not bring the level below the reference level, the operation must be notified to the Swedish Radiation Safety Authority, under Section 4 of the authority's regulations on radon in workplaces (SSMFS 2018:10).

No equivalent notification duty exists for dwellings. There, the obligation is to remediate, not to notify.

SSM can request measurement reports to check whether the notification duty applies, which in practice makes the measurement report the document the whole question hangs on.

Who pays for the measurement in premises we let out?

The law does not answer that, which is exactly why it needs to be in the lease. Responsibility for employees' exposure lies with the employer — the tenant — while the ability to remediate generally lies with you as building owner. A tenant can rarely install a radon sump beneath the slab.

The practical solution is to split it: you as owner take building-related measures, the tenant takes the measurement under the workplace methodology in its premises, and both receive the results. If it is not settled before the measuring season starts, the usual outcome is that nobody measures at all.

Two measurements in the same building

The consequence in a mixed portfolio is concrete: one building may need measuring twice — once under the dwelling methodology for the flats and once under the workplace methodology for the premises, by two different clients.

It is worth co-ordinating even though the responsibility is split. The measuring season is the same, the measurement provider can be the same, and ground-floor premises are by definition in the part of the building with ground contact and therefore the highest likelihood of elevated levels. See radon measurement for measuring season and sampling rules.

When co-ordination is missed, the usual thing happens: the flats are measured, the premises are not, and the building's most exposed space is the only one without a value.

Premises open to the public

A third category worth keeping separate: the 200 Bq/m³ reference level also applies to premises to which the public has access — schools, preschools, libraries, care facilities. There, responsibility for avoiding detriment to health lies with the operator of the activity and with the property owner, with the municipal environmental committee as supervisory authority under the Environmental Code.

For a municipal housing company with preschool premises in its portfolio, that means one and the same portfolio can be hit by all three tracks at once. See the annual calendar for how radon relates to the other inspections, and radon above the reference level for what happens when a measurement comes back high.