Definition: Sibilance is a sound characterized by pronouncing words with the letter 's'. In audio reproduction the letter 's' should sound clear and distinct, not smeared or distorted as in 'sh'.
High air pollution levels can cause immediate health problems including: Aggravated cardiovascular and respiratory illness; Added stress to heart and lungs, which must work harder to supply the body with oxygen; Damaged cells in the respiratory system
Air pollution is the pollution of air by smoke and harmful gases, mainly oxides of carbon, sulfur, and nitrogen. Many of the world's large cities today have bad air quality. Even 2,000 years ago, the Romans were complaining about the bad air in their cities. At that time, the air was thick with smoke from fires and the smell of sewers.