$keys = array_keys($data[1]);

// The key array needs 1 level deeper to access keyNames
     foreach($keys as $k=>$v) {
        $keys[$k] =$data[1][$v];
  echo $keys[$k];

  if(($keys[$k]=='dob')){
 foreach($keys[$k] as &$dobs){
    $date= new DateTime($dobs);
    $dobs= $date->format('Y-m-d');
}

}