On May 31, the world observed No Tobacco Day. Seminars and conferences were organized to mark the occasion with full zeal and commitment. Lately, there has been an alarming increase in young smokers, both boys and girls. In universities and colleges, anti-smoking seminars should be organised to alert the young on the ill effects of the habit. Some 4000 known chemicals are present in tobacco smoke and at least 50 of them are known to cause cancer in humans. According to the International Labour Organization, more than 200 000 workers die every year due to exposure to second-hand tobacco smoke at work. WHO estimates that around 700 million children, or almost half of the world's children, breathe air polluted by tobacco smoke. To ensure smoke-free environment and effective protection at workplace, at public places and homes, concerted effort on the part of both smokers and non-smokers is required. -NAZAKAT HUSSAIN, Islamabad, via e-mail, May 21.