new study by CareerCast, an Internet job board, ranks fire fighter as the most stressful job of 2010, followed by senior corporate executive, taxi driver, surgeon, commercial pilot, public relations executive, advertising account executive and real estate agent. The study assessed more than 200 professions using five core criteria: environment, income, outlook, stress and physical demands to identify the most and least stressful jobs. According to researchers, the economy, having to work harder for less money and less job security, and new technologies that keep us connected 24/7 combine to make for the highest levels of job stress in history. Interestingly, the study found that these high-stress jobs tend to have the lowest unemployment.