A scrim will appear entirely opaque if everything behind it is unlit and the scrim itself is grazed by light from the sides or from above. A scrim will appear nearly transparent if a scene behind it is lit, but there is no light on the scrim. A dreamy or foggy look can be achieved by lighting a scene entirely behind a scrim.
Food or small objects can cause choking if they get caught in your throat and block your airway. This keeps oxygen from getting to your lungs and brain. If your brain goes without oxygen for more than four minutes, you could have brain damage or die. Read more on MedlinePlus.gov.
Swallowing problems may be due to gastroesophageal reflux disease in which acid from the stomach moves up to the esophagus. A tumor or trauma to the throat or esophagus can present the symptom of choking on saliva. Excess saliva is also a symptom of some neurological disorders, such as Parkinson's disease and muscular dystrophy, states Mayo Clinic. Stroke sufferers can also have dysphagia and may choke on either food, liquids or saliva.