Exposure to cold or high-pressure weather may trigger heart failure risk in elderly patients, says a study. Researchers at University Laval and University de Sherbrooke in Canada suggest that elderly patients with heart failure should avoid fog and low cloud in the winter as a preventive measure. Previous research has shown that changes in the weather can affect the health of vulnerable people – for example, heat waves and cold spells have been shown to increase disease and even lead to death in people from low-income neighborhoods. Researchers studied the impact of changes in temperature and air pressure on heart failure patients. The team assessed 112,793 people aged 65 years and older who had been diagnosed with heart failure in Quebec between 2001 and 2011. The participants were followed for an average of 635 days. During this time, the researchers measured the mean temperature, relative humidity, atmospheric pressure and air pollutants in the surrounding environment and studied the data to see if there was an association. The study, published in the journal Environment International, showed a higher risk of hospitalisation or death in the winter period of the year (October to April) compared to the summer period (May to September). Researchers noticed that the risk to experience hospitalisation or death of heart failure cause was increased of 0.7 per cent for every one degree Celsius decrease in the mean temperature of the previous seven days.