Fireworks will be the crowning glory of the Olympic Games' opening and closing ceremonies.

But their importance will not end there, for they will be used throughout the ceremonies to enhance the dramatic effects and highlight the theme of Games, officials in charge of the visual effects have said.

At the beginning of the opening ceremony, 29 spots on the central axis of Beijing, from Yongding Gate to Tian'anmen Square and all the way to the Bird's Nest, will launch special sparklers underlining the theme of the Beijing Olympics.

Fireworks explode over the National Stadium, also know as the Bird's Nest, during a rehearsal for the opening ceremony of the 2008 Beijing Olympic Games at the Olympic Green in Beijing, July 16, 2008. [Agencies]

Cai Guoqiang, the Games' general designer for special effects, said 29 signifies the number of the modern Olympics (Beijing is hosting the 29th Summer Games).

Immediately after the national flag is hoisted and the national anthem sung, 22 spots in the National Stadium with launch fireworks that will explode into dragon-shaped fountains of red peonies and yellow dragons.

The lighting up of the sacred flame will be accompanied by pyrotechnical display at the Juyong Pass section of the Great Wall and the Bird's Nest, giving a past-to-present message. Cai, however, did not say what shapes these fireworks will take.

The climax will have thousands of smiling faces from all over the world.

The sky will be lit up with 2,008 smiling faces emerging from firecrackers.

"The fireworks are not just for people who have tickets to the opening ceremonies," said Cai, a famous artist.

"We want the Olympic spirit to be seen and felt throughout the entire city on the evening of the opening ceremonies."

A trial display on July 16 has already given some people in Beijing a taste of what the fireworks can produce, including one that formed the five Olympic rings.

The real show of fireworks will last a combined 17-20 minutes for the opening ceremony.

Green concerns have not gone unnoticed because the pyrotechnics made by two factories in Hunan province and one in Jiangxi province have special qualities to minimize their impact on the environment.

They are fire-retardant, pose no threat to even the "bubble-covered" swimming center - the Water Cube - and will not leave any residue after burning. To top it all, air pressure, instead of rockets, will be used to launch them.

Combined with digital technology, they will delight the eye as well as add a thematic flourish to China's biggest party.