Smog will remain a problem for at least another five years despite expenditure of $31.45 billion on anti-pollution programmes over the past decade, the public has been warned. Secretary for Environment and Food Lily Yam Kwan Pui-ying also said residents should prepare for high-pollution days in the coming weeks, similar to 12 months ago when they reached near record levels. Mrs Yam, who was briefing the environmental affairs panel on the Government's actions on environmental protection, said it would take time for its measures to take effect. 'On air quality, we have to consider external factors like climate. It takes a long time to reverse the situation. We are aiming at five more years,' said Mrs Yam. The Government's target is to reduce respirable particulates and nitrogen oxide emissions from vehicles by 80 per cent and 30 per cent respectively from 1999 levels by the end of 2005. Mrs Yam said: 'Last March, there were several days with very high readings of air pollution. I cannot rule that out in the coming few weeks; we shall still see very high readings because of changes in air current and climate. I hope people can appreciate it takes time to improve air quality.' She added that major anti-air pollution measures were only introduced about six months ago. Last March, smog blanketed Hong Kong as the air pollution index hovered at the 100 mark, the point at which people with breathing difficulties are asked to take precautions. It reached 162 in Central - only five points off the highest recording of 167 in September 1998. When the index reaches the 100 level - meaning the very young, very old and frail should stay inside - there are 150 micrograms of nitrogen dioxide per cubic metre of air. Panellist Emily Lau Wai-hing of The Frontier said she was disappointed so little improvement had been made, and urged more money to speed up measures. Recurrent spending on environmental protection programmes rose from $1.48 billion in 1990-91 to $5.08 billion in 1999-2000, with a total of $31.45 billion spent over the past 10 years.