American tourists and downtown Washington office workers disproved once again yesterday the song that only mad dogs and Englishmen go out in the noonday sun.

As the metropolitan area's temperature hit 90 degrees or above for the sixth consecutive day, hundreds of music lovers and curious onlookers braved yesterday's heat and humidity to enjoy the sounds of a bluegrass music festival in Farragut Square NW.

Marrie Sciorino, for one, wasn't deterred by the heat from eating her lunch in the noonday sun and enjoying the music of the Bluegrass Cardinals.

"The air seems clearer today," said Sciorino, who works as a program planner for Action, "but I wish it weren't so hot. I feel like dancing.

"I've been having a hard time breathing this summer," Sciorino said, "mainly because of the smog. As a matter of fact, I was afraid to come outside today because the air has been so bad lately, and my eyes have been burning."

In fact, however, the air quality index rating of 60 recorded yesterday was slightly lower than that of Monday, but theair was still polluted enough to be rated "unhealthy" by Environmental Protection Agency analyst Dennis Bates.

To Bluegrass Cardinals singer Randy Granham, though, the pollution wasn't as bothersome as the humidity in the air.

"It makes the strings on our musical instruments sticky," said Graham, whose popular bluegrass group was invited to perform at a recent White House picnic. "But the weather really isn't all that bad. We were in Raleigh last week and we all lost quite a bit of weight playing in the sun down there. Here I'm not sweating all that much."

In the shade beneath a tree next to the Farragut Square bandstand, Debo rah Goodrick, a legal secretary who works nearby, said she often eats lunch in the square, especially when the weather is nice.

"I grew up in rural Maryland," she said above rhythmic clapping to a Cardinal tune. "Eating outdoors makes me feel like I'm in the country again. There's never enough of a breeze in the city."

Ed Cooper, an IBM employee who is visiting Washington for a few weeks from his home in North Carolina, thought the weather here would be cooler than it has been.

"It's really grim down there," he said, speaking f the weather in Winston-Salem, "but this is almost worse, with the smog and all."

Commonwealth Insurance legal secretary Dele Riley agreed. "The heat's terrible today.If it weren't for the fact that I enjoy bluegrass music I wouldn't be out in the sun today.

"I really hope it cools off soon," she said, fanning her face with her hands.

According to the National Weather Service, it won't cool off much at least until next week. The Weather Service's etxended forecast calls for very warm and humid weather through Sunday, with temperatures between the mid 80s and 90s, and a chance of thunderstorms each day in the afternoon.

Some, though, like it hot. Steve Ettridge, a sales representative for Temporarp Staffing, Inc., which along with Executive Staffing, Inc., and the National Park Service sponsored the Farragut Square bluegrass festival, said he was pleased with the weather as well as the turnout.

"Everything is just super," he said, passing out free balloons to passersby. "It's a beautiful day."