Residence halls receiving interventions (i) and (ii) will receive face masks and will be asked to comply with their use at least while in the residence hall when it is known that influenza virus is transmitting on campus. A week's supply of face masks and plastic bags for disposal will be bundled along with instructions for use. They will be requested to wear the masks when out of the halls, but this may be more difficult to implement. As indicated below, we will ask what proportion of time the masks are worn. The choice of the specific face masks will be carried out in conjunction with the CDC project officers. The face mask intervention would require a once a day change during use to ensure proper protection and a hygienic barrier. It is clear from the recent Institute of Medicine report that little is known about long term use or reuse of face masks, so variations in the number of times in which a face mask is changed is a variable that could be assessed in this study.