Poor air quality warning in Melbourne CBD

Pregnant women and people with heart and lung conditions should limit their time outdoors in Melbourne's CBD due to poor air quality.

A warning from the Environment Protection Authority has been in place for most of Thursday, with an afternoon update stating air quality is "unhealthy for sensitive groups".

The elevated level of PM2.5 particles is likely due to wood-heater emissions and other sources of urban pollution not being dispersed because of still atmospheric conditions, the environmental watchdog said.