Asset quality took a turn for the worse at Bank of Queensland over the three months to May 2009.The bank's quarterly disclosure shows that impaired loans increased to $97.4 million at May 2009, up from $38.3 million at February 2009.Loans 90 days or more past due increased to $192 million at May and up from $161 million three months earlier.Most of the growth in impaired loans at BOQ is in the category of "other retail": bad loans in this segment increased to $86.5 million from $34.3 million over three months.Impaired residential loans increased to $10.9 million from $4.0 million over three months.Bank of Queensland's problem loans presumably arise chiefly from two areas: home equity loans made to clients of Storm Financial; and loans made to investors in the bank's underperforming franchises in New South Wales.