In the year 1783 a fissure eruption from Laki in the southern part of Iceland produced a large amount of volcanic gases during a period of eight months. The volcanic gases and aerosols spread across the northern hem sphere due to ideal weather conditions and had a substantial impact on the environment, human health and also climate effects. This, so called dry fog, caused severe health problems, which led to death casualties, killing animals, crops and other vegetation. The consequence was a widespread famine which was aggravated by a hard and long winter in 1783/84. Analysis shows that the Icelandic volcanoes are the primary risk to produce dry fog that can affect Sweden. The fog will most likely cause severe health effects, such as respiratory and cardiovascular problems. It will also cause damage to the vegetation, especially coniferous trees, and it may affect the water by acid chock. The fog may have great impact on the critical infrastructure in Sweden, depending on magnitude and duration. These types of volcanic hazards are difficult to predict and evaluate due to their sporadic nature and the sparse amount of data that is available. It is therefore important to focus on the consequences and develop the Swedish community preparedness on a general basis to handle this type of event.