add_filter('wpseo_breadcrumb_single_link', 'filter_breadcrumbs_for_h1', 10, 2);
function filter_breadcrumbs_for_h1($link_output, $link) {
if ( is_category() ) {
$link_output = preg_replace("/<span\s(.+?)>(.+?)<\/span>/is", "<span $1>Category: ''$2''</span>", $link_output);
return $link_output;
}
else if ( is_tag() ) {
$link_output = preg_replace("/<span\s(.+?)>(.+?)<\/span>/is", "<span $1>Tag: ''$2''</span>", $link_output);
return $link_output;
}
else {
$link_output = preg_replace("/<span\s(.+?)>(.+?)<\/span>/is", "<span $1>$2</span>", $link_output);
return $link_output;
}
}