Conditional for product attribute page

This is the answer:

function active_woocommerce_filters() {

    // for older WC versions
    // global $_chosen_attributes;

    $_chosen_attributes = WC_Query::get_layered_nav_chosen_attributes();

    return count( $_chosen_attributes );

}

https://stackoverflow.com/questions/33229238/woocommerce-check-if-filtering-products