Section 563. Declaration of imminent peril

In the presence of great and
  imminent peril to the public health, the board of health,  having  first
  taken and filed among its records what it regards as sufficient proof to
  authorize  a  declaration  of  such peril, shall take such measures, and
  order the department to do such acts beyond those duly provided for  the
  preservation   of  the  public  health,  including  the  power  to  take
  possession of and occupy as a hospital any building or buildings in  the
  city,  as  the  board,  in  good faith may declare the public safety and
  health  to  demand,  and  the  mayor  shall  in  writing  approve.    No
  expenditure  shall  be  incurred  in  the exercise of such extraordinary
  power, however, unless provision is  made  therefor  in  the  budget  or
  unless  such  expenditures are financed pursuant to sections one hundred
  seven or section 29.00 of the local finance law.  Such peril shall exist
  when and for such period of time  as  the  board  of  health  and  mayor
  declare.