Smoking not only causes cancer, heart disease, emphysema and other diseases, but also affects the health of secondary smokers, said Udom Vinaruenart, senior product manager of Pfizer Consumer Health Care Ltd, a market leader in nicotine-replacement products.

Udom said children with smoking parents were twice as likely to have health problems, while their lung development and general growth were affected.

"Each year, about 50,000 people die from cigarette smoking, or about six deaths per hour. The age group with the most heavy smokers is 25 to 34," said Worayuth Watcharotayangkoon, general manager of Pfizer.

He said his company's nationwide survey found that nearly 60 per cent of respondents, or about 1.7 million people, wanted to quit smoking but were disheartened and lacked support.

Quitting smoking by oneself took six to eight attempts before the mission was accomplished, said Worayuth, whose company launched a "Welcome Back to Smoke-free Life" campaign at Bangkok's Siam Discovery Centre yesterday for smokers' family members and friends to motivate them to quit smoking.

As part of the campaign, 400 paintings with the theme "life after quitting smoking" were submitted by primary students in a nationwide contest.

The winner was fifth-grader Nattapas Manasilpaphan, of Bangkok's Sarasas Witaed Romklao School, who received Bt15,000 prize-money and a plaque of honour. Runners-up were sixth-graders Ditthakul Yimthanom, of St John's School, Bangkok; and Kittiya Rongkaew, of Siriwittaya School, Samut Prakan.

Worayuth said the winning paintings would be printed on 50,000 postcards to be handed out to the public along with a handbook on quitting smoking.