A bit grubby

Went off for a walk after lunch, looking for detail as I went. No great photos were taken, but my attention was caught by these 'white' screens by the roundabout. Not sure if they are more about noise, aesthetics, safety or pollution but, judging by the state of them, some exhaust fumes are definitely being fielded by it. Not sure what's causing the lighter marks on it but, if it's slugs or snails then I think they need a better sat nav. Decided to go mono for Mono Monday.