Add category slugs to loop in wordpress - html

Question

I don't know if I've used the best title for this question but I'm not sure exactly how to phrase it. I've successfully setup a filterable portfolio script on my site but I need to apply the appropriate class to each item. Right now I've got this.
<?php $loop = new WP_Query( array( 'post_type' => 'productions', 'posts_per_page' => -1 ) ); ?>
<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
<div class="tile web all"> <?php the_post_thumbnail ( 'home-page' ); ?>
<h1><?php the_title(); ?></h1>
</div>
<?php endwhile; wp_reset_query(); ?>
The class "web" is just an example, it needs to be replaced by the slug(s) for the categories used for that particular post, as I've setup the filters to automatically show all the categories like this:
<div class="filters">
<p href="" data-rel="all">All</p>
<?php
$args = array(
'type' => 'productions',
'orderby' => 'name',
'order' => 'ASC',
'taxonomy' => 'production_type',
);
$categories = get_categories($args);
foreach($categories as $category) {
echo '<p data-rel="' . $category->slug.'">' . $category->name.'</p> ';
}
?>
Hopefully that is enough info for some help. Thanks.

Answer 1

This worked:
<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
<div class="tile <?php
$terms = get_the_terms( $post->ID , 'production_type' );
foreach ( $terms as $term ) {
echo $term->slug;
echo ' ';
}
?> all"> <?php the_post_thumbnail ( 'home-page' ); ?>
<h1><?php the_title(); ?></h1>
</div>
<?php endwhile; wp_reset_query(); ?>