Fair use etc http://www.chron.com/cs/CDA/story.hts/metropolitan/597754 July 7, 2000, 10:12PM 'Very unhealthy' smog recorded The metropolitan area's first "very unhealthy" smog reading of the year was recorded Friday at a central Houston location. State officials also issued an "ozone watch" for today, meaning weather conditions were expected to be conducive to more high ozone levels. The measurement of ground-level ozone, smog's main ingredient, triggered the first purple-level alert since a color-coded warning system was introduced this spring. The ozone reading of 206 parts per billion (ppb) was at a state monitoring site at 2425 Polk, near U.S. 59. The national health standard for ozone, a respiratory irritant that forms when other pollutants mix, is 125 ppb. In government officials' color-keyed system of alerts, orange warnings indicate readings of 125 to 164 ppb, deemed "unhealthy for sensitive groups." Red is for measurements of 165 to 204 ppb, "unhealthy" for all. Purple is for levels 205 ppb and higher, meaning "very unhealthy." Besides the 206 ppb reading, ozone measurements ranging from 131 to 201 ppb were recorded at six other Houston-area sites Friday. The area's highest ozone reading last year -- also the nation's highest -- was 251 ppb. -- BILL DAWSON

-- mike in houston (mmorris67@hotmail.com), July 08, 2000