When a structure burns, factors like hallways, windows and room size can create unpredictable ventilation and wind conditions that can trap occupants and make firefighting more difficult. Last year, the National Institute of Standards and Technology and New York City Fire Department experimented with positive pressure ventilation, a process using portable fans to direct a fire's heat and ventilation through a desired point. When heat and smoke controllably exit a structure, the rescue and suppression teams are more effective. In this image, fire is forced out of an upper window to help prevent or delay structural collapse.

Chad Vander Veen  |  Associate Editor