Firefighters want their blood as well as all training sites urgently tested for toxic chemicals from firefighting foam.
The union is accusing Fire and Emergency (FENZ) of not doing enough to investigate or monitor staff health.
It "took issue with the prioritisation methods FENZ was relying upon, the delay, that few if any sites might be tested, and the lack of any investigation or monitoring of firefighters' health," a union statement said.
The group of chemicals known as PFAS has been linked to cancer, and two of them - PFOS and PFOA - have been banned from use in firefighting foam since 2006.
The Professional Firefighters Union said FENZ was not testing enough sites and was taking too long to get started.
The union also did not accept the agency's advice that the risk to health from PFAS exposure was 'very low' - and demanded that advice be extensively reviewed.
"All of our members should be offered voluntary blood testing ... all training grounds should be tested," the union said.
It wants all its members to be offered voluntary blood tests and get proper advice on what the results mean.
Union secretary Wattie Watson said members were hopeful FENZ would fund the blood tests after it agreed to meet with experts this week.
"One of the best things we've heard this week is that FENZ is now going to go and talk to the experts that we've pointed them to and in particular in Australia where fire-fighters are being [given access to] voluntary bloodtests."
"I think once they've spoken to them they will understand the need for the blood tests and get that done relatively quickly."
The union wants the tests available to all professional firefighters, as well as help made available for when the results come back.
Firefighters would need support if they had high levels, and advice on whether there was some action they could be taking, he said.
Ms Watson said firefighters at training centres who had used the foam over many years would have higher exposure than others and would welcome the tests.
A year ago Fire and Emergency said it would carry out a nationwide investigation into fire brigade training locations at Mt Wellington in Auckland, Rotorua, Kilbirnie in Wellington, and Woolston in Christchurch.
It said at the time it was not moving fully to fluorine-free foams as it could not find one that was effective enough - even though Australia brigades went fluorine-free several years ago.