The Light Cycle project, though not his biggest, will be the grandest Cai has created in the United States. The four-minute spectacle, which took the artist six months to design, will consume 12,000 shells and cost the sponsor, ice-cream maker Haagen-Dazs, $300,000. More than 150 society dinners have been organised in the Central Park area in conjuction with the display, with celebrity guests including former US president Bill Clinton, New York mayor Michael Bloomberg and actors such as Michael Caine, Sigourney Weaver and Sarah Jessica Parker.

The first phase will involve five 200-metre tall pillars of fire lit one by one. These Signal Towers are meant to remind New York that Central Park, now visited by 25 million people a year, once belonged to native Americans who communicated over long distances using fires and smoke signals.

The second stage will feature four giant halos, three horizontal and one vertical, the latter being 305 metres in diameter and provided it is a clear night viewable for miles around. In the final part, thousands of shells will be shot in the air simultaneously, bathing the park in a giant flash of light. 'The Light Cycle will draw an amulet on Manhattan's chest and protect her from being hurt by evil,' says Cai.

The spectable bears some similarities to the Transient Rainbow, a firework project he staged in June last year to mark the Museum of Modern Art's temporary relocation from Manhattan to the neighbouring New York borough of Queens. The 15-second rainbow display across the East River from Manhattan to Queens impressed New Yorkers not only because it was apt but also due to the splendid colour and for the optimism it represented after September 11.

These more positive works are a change from some of Cai's previous explosive efforts, in which the fire and smoke cleared to reveal debris and destruction. In his 1990s series, Project for Extraterrestrials, Cai built a tent-like home beside the Tama River near Tokyo and exploded it to show how to spiritually leave this world and enter another dimension. The violence continued in the 1996 project called Century with Mushroom Clouds, Cai's first explosive work in the US, in which the artist created small-scale 'mushroom clouds' beside the Hudson River.

But after the destruction of the World Trade Centre, Cai says he wants to 'create something positive and constructive to show people hope'.

Ironically, the artist has found it easier to get permission from the US authorities for his explosive projects after the terror attacks. 'It was not easy to get permits to do explosive work in big cities like New York. But it is much easier after September 11. And I also got more invitations. It seems people could understand and appreciate the art of fire and light, the positive side of explosion, better than ever,' says Cai, who also was invited to do a project across the Thames River in London last January, and is preparing to create a firework pagoda beside the Eiffel Tower in Paris next January.

Rapid developments in explosives technology are providing Cai with increasing possibilities. In Light Cycle, the artist uses microchips in the shells to control the timing and place of explosions, and therefore the display of light and fire. The vertical halo, for example, is created by shooting out shells for the top end of the circle seven seconds earlier than those for the bottom but exploding them simultaneously.

'The microchip technique was originally developed for targeting by the military. Now I am making it constructive rather than destructive,' says Cai, adding that this also reflects the contradictions in the history of gunpowder and even civilisation itself.

Known in Chinese as huo yao, meaning fire medicine, gunpowder was one of the four great inventions of ancient China (the others being the compass, paper making and the art of printing). It was a by-product of the search for eternal life, but was used to destroy lives in military campaigns. 'I think people accept my explosive art universally not only from the artistic perspective, but also because of the collision of civilizations reflected in it, mirroring a common spiritual struggle of mankind,' says Cai.

Cai, 46, was born in Quanzhou in southern Fujian province. The coastal Chinese city closest to Taiwan is known for its firework manufacturing, and he grew up to the sound of fireworks and artillery blasts from military manoeuvres around the Taiwan Strait. Turning to gunpowder in the mid-1980s might have seemed entirely natural, but the artist had little choice.

'At that time, there were few channels in China to learn what mediums were being used in the international art world, but gunpowder was the easiest thing to get in my home town,' says Cai.

The light, fire and smoke he causes through explosions provides the soft-spoken Cai with immediate pleasure and relief, he says.

Looking more like an ordinary worker than a radical artist, Cai nevertheless struggles to free the 'violent artistic passion' within him. In his 1992 work Foetus Movement 2, the artist placed himself in the centre of a 1,300-metre circle of explosives and recited a passage from the ancient philosopher, Lao Zi, on the birth of the universe while blasts went off.

Still, Cai rejects categorisation. 'I don't belong to the vanguard group which takes pleasure from being anti-government. Nor do I belong to the official artists group who frown on the vanguard. I liberate my spirit through my own work,' says Cai, who believes the essence of art is to borrow from the power of nature.

Despite the constant comparisons with Land Art, a western art form characterised by large outdoor works, Cai insists his art is completely rooted in eastern culture, not only because of the medium, but also because of the philosophy that underpins the work. This focus grew more pronounced from 1986 to 1995 when Cai lived in Japan, cultivating his long-time interests in Taoism, Zen philosophy and astrophysics.

But this style was challenged when he immigrated to the United States in 1995. Facing mainly a western audience who appreciated visual impact better than abstract philosophy, Cai has had to adjust his style.

His 1998 project, Borrow Your Enemy's Arrows, perhaps best illustrates Cai's feelings about this cultural conflict. Now part of the New York MOMA collection, it features a wooden boat suspended in mid-air studded with 3,000 arrows. An electric fan keeps a Chinese national flag fluttering at the stern.

While Arrows was criticised in the west as nationalistic, Cai was condemned in his homeland as a banana artist: yellow on the outside but white on the inside. But Cai shrugs off the attacks. 'Cultural conflict is like this. It can make you black and blue, but after you absorb it, it could give you new power, he says.