Pollution levels were too high for the staging of the Standard Chartered Marathon last Sunday and runners should have been advised against taking part, international experts say. Organisers of the marathon last week said they may ask runners to submit a sports history following the death of a runner days after taking part in the race. Tsang Kam-yin, 53, died on Tuesday after collapsing on the Tsing Ma Bridge, 13km into the race. Professor Robert McConnell, of the University of Southern California's Keck school of medicine, said that while no benchmarks existed on when an event such as a marathon should be cancelled, he would not have recommended running at the levels of pollution last Sunday. The air pollution index reached a 'very high' 149 in Causeway Bay on the day and 147 in Central. Dr Antonio Miguel of the University of California's Institute of the Environment said he would not recommend exercising outdoors at such high pollution levels. Professor James Sharman, of the University of Queensland's faculty of health sciences, agreed, saying that as a jogger himself, he would not run in such conditions. Annelise Connell, of Hong Kong's Clear The Air, said not enough was done to highlight the risks involved in running in such pollution. 'At the very least, there should have been a general air pollution alert to warn runners that their health was at significant risk,' she said. The Environmental Pollution Department said the marathon route was mostly vehicle-free, and roadside APIs were 'not too relevant'. 'The department maintained close contact with the organiser and provided information on API. It would be at the organiser's discretion whether to cancel the event,' the department said. Professor Wong Chit-ming, of the University of Hong Kong, said organisers could consider moving the race to a less polluted area to minimise the effects of pollution. Chinese University respiratory division head David Hui Shu-cheong agreed, saying the location of the marathon route in the middle of a busy city was less than ideal.