A man walks atop the crest of the Xilicatzi hill in Totolac, Tlaxcala, Mexico while ash and smoke are spew from the Popocatepetl volcano on July 4, 2012. According to a report by The National Center of Prevention of Disasters (CENAPRED) during the last 24 hours the Volcano has emitted at least 15 breaths and it has been declared a yellow alert. AFP PHOTO/ Guadalupe PEREZ