This means (for those with a chronic illness or damaged lungs) stay in the warm, or if you do have to go out, wrap up warm and don't stay out in the weather for too long. Further reading about this warning, view web address as below (you may have to copy paste it into your browser).
www.metoffice.gov.uk/public/weather/cold-weather-alert/#?tab=coldWeatherAlert
Warning issued 10 March 2013
Some parts are experiencing 0 degrees and feels like -7C !
Take care and keep warm.
Soon be spring the flowers are popping up all around the garden. Patience Vee2 nature will be here in her own good time after waiting all winter awhile longer is easy done.
Keep positive this will pass soon enough we all have plenty of time on our hands with a lung condition nothing works by hurrying
Hi Vee,
Temperatures here are minus at night and morning. If I go out in the mornings I make sure I have a mask on to avoid the cold air going into my lungs.
Regards,
Robert.
Good thinking Robert. 
The flowers are up already Limpet. Soon be Easter, keep smiling :D
Keep warm and have a great weekend.