Organisers of Wales' largest running event took a stand against plastic yesterday, warning participants they would be disqualified if caught littering.
Runners in the Conwy Half Marathon were told ahead of the race that they would be "taken off the results" if seen discarding their rubbish outside of water stops or not with a marshal.
Organisers said consequences had to be introduced as plastic was becoming an "increasing problem".
Of the 3,000 runners who took part, no one was disqualified under the new rule.
Run Wales is one of a number of races implementing new rules to help reduce its environmental impact.
Earlier this year, the London Marathon trialled similar measures in a bid to reduce litter including the use of compostable cups and using bottles made from recycled plastic.
The changes came following the 2018 event when organisers cleared 47,000 plastic bottles from the streets.
The London Marathon also introduced edible water pods made from seaweed extracts.
Meanwhile, this year's Cardiff Half Marathon introduced 100 per cent recyclable bottles and recycled paper for print advertising.