A wnaiff Ysgrifennydd y Cabinet gadarnhau pryd ydd y data o dreial Llywodraeth Cymru i ymestyn y parth 50mya heibio Port Talbot ac Abertawe ar draffordd yr M4 yn cael eu cyhoeddi?
Wedi'i ateb gan Ysgrifennydd y Cabinet dros yr Economi a Thrafnidiaeth | Wedi'i ateb ar 14/11/2018
The effect of the measures on NO2 concentrations at the five trial 50mph locations is currently being monitored by diffusion tubes. This will be supplemented with continuous monitoring using reference method analysers by the New Year.
The earliest date that a full set of validated annual data will be available is September 2019 and the information will be published thereafter.