In 2009, Italian scientists (need hyperlink to study) studied the effects of putting a photocatalyst in a pig barn.  As expected the light-activated chemistry worked to break down many airborne pollutants, and the ammonia levels in the air dropped.  The pleasant surprise was that the pigs in the barn were healthier, and produced a higher yield on their feed.  More research is needed about this exciting opportunity to make our food chain healthier by improving the quality of the air.