Sir: We all agree there is too much plastic waste around, so charging for plastic bags seems at first sight sensible (‘Campaigners press England to join rest of UK on bag charge,’ 13 April). However, plastic bags are immensely useful. They are used and re-used many times and have better environmental and health credentials than paper bags or thick durable bags. We should charge only for those that are not degradable.

The case for oxo-biodegradable plastic is compelling. Although, like ordinary plastics, it can be recycled or incinerated for energy recovery, it was developed to address the problem of plastic that escapes into the environment and lies or floats around for decades.

It is manufactured with a pre-set lifespan (from as little as six months). It is thus the only plastic you can “tell” when to degrade and won’t exist for long enough to form an environmental hazard or eyesore. It degrades automatically as long as it has access to oxygen and is not toxic. This doubtless explains why oxo-biodegradable bags are growing in popularity and are compulsory in some countries.

Michael Stephen, director, Symphony Environmental Technologies