Worst condition?

From the requirements: "Verify performance of the smoking rooms’ differential air pressures by conducting 15 minutes of measurement, with a minimum of 1 measurement every 10 seconds, of the differential pressure in the smoking room with respect to each adjacent area and in each adjacent vertical chase with the doors to the smoking room closed. Conduct the testing with each space configured for worst-case conditions of transport of air from the smoking rooms (with closed doors) to adjacent spaces." It seems to me that having doors open is the worst case, not doors closed. Any opinions on that?