In most cases phlegm gets accumulated in the chest when the patient is suffering from bronchitis where the mucous membranes that line the bronchial tubes in the lungs get inflamed.
So this inflammation of the bronchi causes a large quantity of mucous to be secreted which is therefore expelled from the body as phlegm.
And foremost, the patient must avoid smoking and be careful with from smokers as well.
Whenever lowering their resistance to disease and allowing harmful bacteria from the atmosphere to attack the body, even passive smoking can irritate the bronchial tubes. Besides, a change in weather conditions can also lead to this condition. Other causes include the use of drugs for other medical conditions, work in a stuffy atmosphere and occasionally hereditary factors. You can consume half a teaspoon of turmeric powder dissolved in warm milk and had on an empty stomach, in order to rid of phlegm in the chest. With that said, this process can be repeated twice or thrice a day for best results. Expectorant properties of onions make them an excellent remedy for this condition as they have the ability to liquefy phlegm and prevent it from reforming. Nevertheless, another good way to consume onions should be to crush them and extract the juice which can therefore be had on an empty stomach almost any morning.
Reference to: http://www.yogawiz.com/