Water samples taken by the Health Board late last week showed that a toxic algae bloom has reached Kakumäe beach in suburban western Tallinn, bringing the number of affected beaches to five.
In the Tallinn area, the other areas are Haabneeme, Stroomi and the freshwater Lake Harku; and on Hiiumaa Island, Kärdla.
The samples taken in Haabneeme and Kakumäe on August 1 showed the water was cloudy, which in turn signaled the presence of cyanobacteria, often called blue-green algae.
The Health Board cautioned people with allergies as well as small children and older people against swimming in "blooming" water. The cyanobacteria can cause skin irritation and rashes and if ingested, gastrointestinal symptoms; special care should be taken not to inadvertently swallow water.
Conditions are highly variable, and a change in wind direction can often flush the irritant out of a given beach area in a matter of hours.
The latest data showed that Pirita and Pikakari beaches are currently the cleanest in Tallinn.