Pollution scientists who developed a new air quality alert system for the government that was never adopted plan to launch it themselves. The experts say their air quality health index (AQHI), to be provided on a website as early as next month, will offer the public better, clearer and more timely advice on health risks than the present government system. Modelled on a Canadian approach, the new index will be calculated on the risks of hospital admissions for respiratory and cardiovascular diseases from the sum of four air pollutants - sulphur dioxide, nitrogen dioxide, ozone and particulate matter. The current air pollution index (API), introduced in 1995 and never revised, does not take health risks into account and is based on the highest level of concentration on a given day of just one of the four pollutants. Friends of the Earth welcomed the new index but said the government should replace its own system. "The public is numb to the severity of the air pollution levels as the numbers are always high," senior environmental affairs officer Melonie Chau Yuet-cheung said. "They do not know how to interpret API figures." The scientists, who work for local universities, were commissioned to develop the system for the Environmental Protection Department in 2009 but it was never adopted. They plan to launch their unofficial system as soon as they can secure a supply of raw data from the department's roadside and general monitoring stations. A spokesman said the department was still studying the proposal but pledged to revamp the alert system in parallel with an upgrade of the government's air quality objectives - the targets it sets itself for the levels of various pollutants - which is expected to be complete by 2014. He said it had taken time to assess the scientists' proposals. A member of the scientific team, Professor Wong Tze-wai, from Chinese University's School of Public Health, said the new index would have seven bands, ranging from low to serious health risk categories. The website will give specific advice to groups most at risk, including outdoor workers and people with illnesses, on what to do and when to restrict or reduce outdoor activities. "The daily index will bring short-term effects, such as changing an individual's day-to-day activities, but the year-long average will serve as a guideline for the government to take necessary measures in the long run," he said. Another developer of the system, Professor Alexis Lau Kai-hon, an atmospheric scientist from University of Science and Technology, said a direct and comprehensive supply of raw data was crucial for the launch. "As long as the EPD publishes the necessary data for all four pollutants, the website is good to go. But we are still trying to figure out what to do if one or two figures are missing," Lau said. Friends of the Earth's Chau said the new index would offer an alternative online from which to take reference, "but the sooner the government can replace the API system, the better".