You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allfileusages gafcontinue="הראל_וייס.jpg|17" />
  </query-continue>
  <query>
    <pages>
      <page pageid="3" ns="0" title="מחלת אסטמה" />
      <page pageid="4" ns="0" title="זיהום אויר" />
      <page pageid="5" ns="0" title="זיהום אויר ובריאות האדם" />
      <page pageid="7" ns="0" title="בירוא יערות ואפקט החממה" />
      <page pageid="17" ns="2" title="משתמש:Mehg" />
      <page pageid="38" ns="0" title="מחלות ריאה" />
    </pages>
  </query>
</api>