Longer Flights and Winter Tied to Increased Blood Clot Riskhttp://articles.mercola.com/sites/articles/archive/2001/09/22/blood-clot-risks.aspxBlood clot formation in the leg veins, a condition known as deep vein thrombosis (DVT), is much more likely to develop during winter months than in the summer . Similar seasonal variation in a related, potentially fatal condition known as pulmonary embolismenCommunityServer 2008.5 SP1 (Build: 31106.3070)