Yng Nghymru, mae ansawdd aer gwael yn cael effaith arbennig o amlwg ar iechyd y rhai mwyaf agored i niwed – fel yr ifanc iawn neu'r hen iawn, neu bobl â chlefydau cardiofasgwlaidd a chyflyrau anadlol fel asthma a Chlefyd Rhwystrol Cronig yr Ysgyfaint (COPD).
In Wales, poor air quality has an especially pronounced impact on the health of the most vulnerable – such as the very young or very old, or people with cardiovascular diseases and respiratory conditions like asthma and Chronic Obstructive Pulmonary Disease (COPD).