"We've had this discussion so many times I think it should be banned until management bring us some plan about what should happen," he told the advisory committee meeting this week.
Waiting times at Dunedin Hospital and Southland Hospital EDs frequently exceed national targets.
Part of the problem is seen as too many patients turning up in the first place.
The topic comes up month after month and some members have pushed for more action to address the problem of attendances.
At their meeting on Wednesday, members discussed the system for rural patients to be dealt with through city EDs, and whether ED staff were ordering unnecessary procedures.
New chief executive Carole Heatly indicated to Mr Thomson the topic was still new to her, and one she wants to address.
Ms Heatly, a Scot who until last year ran a university hospital trust in northern England, said the fact only a third of patients were admitted to hospital indicated they should not be coming to ED.
The DHB would work with the GP and community health sector to treat less serious ailments in primary care, she said.
It was possible new facilities needed to be established.
This week's implementation of free doctors' appointments for under-6s showed the DHB could work with primary care, she said.
Patient services executive director Lexie O'Shea said surveys of Southern patients indicated they attended ED unnecessarily not to avoid the cost of a GP, but because "that's what you do".
The committee was advised that in May Dunedin Hospital had 3413 ED attendances, of which 29% were admitted. At Dunedin, 88.3% of patients were treated or transferred from the department within six hours, against a target of 95%.
In Southland, 93.5% of patients met the target.
The 6 Hours - It Matters! initiative under way at both Southland and Dunedin hospitals is addressing the efficiency of their EDs, and how patients move through the hospital system.
