Debug Bar getting in the way

I have a controller that among other things downloads a csv file. But my downloaded file contains my data plus the debug bar html code! How do I get rid of this?

PHP Code:

public function download_names($rcseq)
    {
        $db = new \App\Libraries\NcrsEbnDb();
        $rows = $db->getRCNames($rcseq);
        header("Content-type: text/csv");
        header("Content-Disposition: attachment; filename=names-$rcseq.csv");
        ob_clean();
        flush();
        foreach ($rows as $row)
            print $row['NAME'] . "\r\n";
    } 


Simpler is always better