The lining of the airways becomes inflamed and starts to swell and mucus or phlegm can be produced.

BBC: NEWS | Health | Overweight 'higher asthma risk'

Then comes the staccato sound of Clay Rapada clearing his throat, as he tries to get the phlegm out.

WSJ: The Yanks Need Some Chicken Soup

Mandy made to move past him, and he cleared his throat, for comedic effect, she figured, though she could also hear phlegm swirl.

NEWYORKER: Deniers

Elizabeth Shassere, from Herefordshire Council, said anyone with symptoms of coughing and wheezing, breathlessness, phlegm or chest pain should seek medical advice from their GP.

BBC: Fire on Rotherwas Industrial Estate

Many of the soldiers who went through Balad since the beginning of the war became used to "Iraqi crud, " as they dubbed the symptom of excessive coughing and black phlegm.

CNN: Congressmen want more info on 'burn pit' claims

In a 2003 study, Kelly and her collaborators found that men and women with diets high in vitamins C and E had greater lung capacity and produced less phlegm, respectively.

CNN: Vitamin E may protect lungs

"In On The Road, he talked about 'spitting at stars' at one point, and yeah, I really liked the idea of having phlegm in the air, to see where it lands, " Penate says.

NPR: Jack Penate: South London Pop Flair

Phlegm production and wheezing are also COPD symptoms.

CNN: Vitamin E may protect lungs

Woods, arguably still golf's biggest star despite his fall from grace in the past two years, fell foul of the sport's disfavor for phlegm in February 2011 during a frustrating final day at the Dubai Desert Classic.

CNN: Spitting mad: Golf star's antics spark Twitter campaign

Those who continued to rely solely on their medication scored 33.5 in the St George's Respiratory Syndrome Questionnaire - a survey which asks patients questions such as how often they have coughed, wheezed or brought up phlegm.

BBC: NEWS | Health | Breathing technique 'aids asthma'