This reflects the high share of heavy industry and electricity generation in Wales (e.g. emissions from power stations, refineries and integrated iron and steelworks).
Adlewyrcha hyn lefel uchel y diwydiannau trwm yng Nghymru a'r ffaith y cynhyrchir cymaint o drydan (ee allyriadau o orsafoedd pŵer, purfeydd a gweithfeydd haearn a dur).