A POLLUTED WORLD: Atmospheric chemist Joseph Prospero has a satellite image of the globe's aerosols -- which he calls deadly.

Air pollution may have caused the plane crash that killed John F. Kennedy Jr. and his two passengers on July 16, a University of Miami scientist said Tuesday.

Pollutants that drifted from smokestacks and exhaust pipes from as far away as Ohio caused the ``haze'' that reportedly obscured Kennedy's visibility a half mile above Martha's Vineyard on the night of the crash, according to Joseph Prospero, director of UM's Institute for Marine and Atmospheric Studies.

``All the news reports talked about the haze that night and how it was caused by heat and humidity, Prospero said in an interview. ``But haze is always caused by very high concentrations of pollution particles.

``I believe that high concentrations of visibility-reducing aerosols were the cause of the crash that killed Kennedy and his passengers.

Kennedy, his wife, Carolyn Bessette Kennedy, and her sister, Lauren Bessette, were killed when the plane Kennedy was piloting from Fairfield, N.J., plunged into the ocean off Martha's Vineyard.

Prospero, an atmospheric chemist, studies the long-distance movements of airborne pollutants and dust on the trade winds. He is best known for his studies of the trans-Atlantic movement of large amounts of dust each summer from northern Africa to the southeastern United States, a phenomenon he has been tracking for more than 30 years.

He said he decided to prepare an analysis of the Kennedy crash to help people understand problems caused by air pollution worldwide.

An analysis of weather information and computer models of the transport of pollutants that evening showed maximum concentrations of tiny particles of pollution known as aerosols were directly over the waters around Martha's Vineyard, Prospero said. And federal satellite data also showed a sharply defined band of very high particle concentrations in the same area, he said.

The pulsing of large amounts of airborne pollutants off the East Coast at the end of the week is a well-documented phenomenon. Last year, researchers at Arizona State University reported findings that showed that smog and soot belched into the air by power plants, factories and cars during the long week of work wafted offshore by late Friday and was responsible for an increased likelihood of weekend rain showers.

``We know from models that there's a path that transports pollutants that runs across the New England states, Prospero said. ``It just so happens that a good heavy pulse that came out that weekend of July 16.

Prospero's analysis showed that concentrations were greatest the night of the crash at about 3,000 feet and decreased above that.

According to Prospero's analysis: At Kennedy's cruising altitude of about 5,600 feet, he would have been above the pollution. And as the plane flew east over land, he would have seen a relatively clear sky overhead and could have seen lights and other details through the pollution haze.

``The situation would have changed drastically as he approached his destination and started his descent, Prospero said in his written analysis.

At 9.26 p.m., Kennedy was off Westerly, R.I., as he began to head over the water to Martha's Vineyard. He was 34 miles out and at 5,600 feet when he began to descend at 700 feet a minute.

The descent continued for about five minutes to 2,300 feet when the plane was about 20 miles from the airport. This would have put him in the middle of the pollution layer, Prospero said.

Because of his altitude and distance from the airport, he would have had to look down at a slight angle through the densest part of the pollution layer. Under those conditions, the airport and the horizon were most likely completely invisible, Prospero said.

With his view of the airport obscured, Kennedy apparently decided to climb to a higher altitude, Prospero said. Radar showed he climbed to 2,600 and then vanished.

``Kennedy was unwise when he decided to fly at that late hour. Nonetheless, he seemed to have been doing all the right things until very late in his flight when he started his descent.

``I suggest the ultimate cause of the crash was a low-lying layer of pollution that disoriented him in the final moments of his flight, so close to his destination, invisible in the haze, Prospero wrote.

If pollution indeed was a contributing factor to the Kennedy crash, it wouldn't be the first time. In September 1997, an Indonesian airliner crashed in haze caused by forest fires on Sumatra, killing 234 people.

``We have come to accept pollution haze and poor visibility as a normal feature of our environment, Prospero said. ``All over the world, visibility is being degraded because of increased concentrations of pollutants.