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
Toxic air pollution persists in hundreds of U.S. communities. Breathing Easier: How Houston Is Working To Clean Up Its Air Breathing Easier: How Houston Is Working To Clean Up Its Air Intensely smoggy days are striking less often thanks to better technology that pinpoints problems, and laws that have prompted fixes. Still, scientists say they haven't yet tracked down all the sources of the pollution fouling the region's air.