SINGAPORE - When Mr Dustin Onghanseng, 35, was pursuing a masters of business administration at the Hong Kong University of Science and Technology from 2013 to 2015, he often went to class sneezing or with a runny nose.

The Singapore permanent resident, who was born in the Philippines, had hay fever allergies that were triggered by cleaning agents or mould along the corridors and in his dormitory. Meanwhile, his coursemate, Mr Brian Lin, suffered from asthma attacks.