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
11 U.S. Cities With the Worst Air Pollution. The good news: Air has gotten cleaner in recent years. Now the bad: More than half of people in the U.S. still breathe air dirty enough to cause health problems, according to the American Lung Association.1 U.S. Cities With the Worst Air Pollution. The good news: Air has gotten cleaner in recent years. Now the bad: More than half of people in the U.S. still breathe air dirty enough to cause health problems, according to the American Lung Association.