Close to a million people attending hospital emergency departments each year agree they could have been treated elsewhere, a new report suggests.

The survey of NSW emergency department visitors found two-in-seven thought their condition "definitely" or "to some extent" could have been treated by a GP or other health professional.

However, most also said their preferred GP or health service was closed or had no suitable appointments at the time.

The NSW Bureau of Health Information survey was released on Wednesday alongside data showing doctors and nurses remained under pressure in the September quarter.

The number of emergency department patients waiting longer than recommended rose to a record high of 38.7 per cent, the bureau found.

Medical unions used the data to demand better funding and staffing, with one highlighting a disconnect between what doctors wanted to do for their patients, and what limited resources and staffing allowed them to do.