 investigated whether some or all of the spike in cardiac mortality that occurs during December and January could be ascribed to the Christmas/New Year's holidays rather than to climatic factors.They concluded that the Christmas and holiday season is "a risk factor for cardiac and noncardiac mortality", stating that there are "multiple explanations for this association, including the possibility that holiday-induced delays in seeking treatment play a role in producing the twin holiday spikes".The Asthma Society of Canada states that the Christmas and holiday season increases exposure to irritants because people spend 90% of their time indoors, and that seasonal decorations in the home introduce additional, further, irritants beyond the ones that exist all year around.