Indoor Air Radon Concentration in Premises of Public Companies and Workplaces in Latvia.

Considering the multitudes of people who spend their time working indoors in public premises and workplaces, it is worth knowing what their level of exposure is to natural radioactive radon gas, the second most widespread and dangerous carcinogen for lung cancer development after cigarette smoking. This state-level study covered most of the territory of Latvia and conducted 941 radon measurements with Radtrack2, placed for 4-6 months in the premises of public companies, educational institutions, medical care institutions, etc. The study found that 94.7% of samples did not exceed the national permissible limit (200 Bq/m 3 ), the level at which preventive measures should be initiated. The median value of average specific radioactivity of radon in these premises was 48 Bq/m 3 (Q1 and Q3 being 27 and 85 Bq/m 3 ), which is below the average of the European region. Slightly higher concentrations were observed in well-insulated premises with plastic windows and poorer air exchange, mostly in schools (59 (36, 109) Bq/m 3 ) and kindergartens (48 (32, 79) Bq/m 3 ). Industrial workplaces had surprisingly low radon levels (28 (16, 55) Bq/m 3 ) due to strict requirements for air quality and proper ventilation. Public premises and workplaces in Latvia mostly have low radon concentrations in the air, but more attention should be paid to adequate ventilation and air exchange.