Bush fires on the outskirts of Sydney are expected to affect the third cricket test between New Zealand and Australia today.
After a relatively clear first day during which air quality never dropped below a "fair" rating, the weather is expected to bring smoke from fires into the city which will negatively affect that rating.
New South Wales' Department of Planning, Industry and Environment has predicted an air quality rating of "poor" for today's play as the city deals with sweltering 45C heat and blustery winds.
The Black Caps have said they are happy to follow advice from Cricket Australia and match officials when it comes to how this could affect play.
"We're comfortable with them (the guidelines)," Black Caps coach Gary Stead said after day one.
"We will be ready to go in the morning to the best of our ability and if it gets taken out of our hands, then that is the umpires' and match officials' call."
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The ICC's guidelines state that in this situation Cricket Australia will report to match officials on air quality and visibility ratings, while team doctors will also pass on any concerns for the respiratory health of players.
If the air quality within the Sydney Cricket Ground is judged to be too poor, players will leave the field and wait until conditions improve, much like a rain delay.
Cricket Australia's head of operations Peter Roach has conceded that the umpires might be forced to take the players off the field at some stage.
"What we've seen in Sydney and Canberra is that it comes to a point where it becomes a challenge. Rules are in place, like rain, to add time for suspended play," he said.
"What we are finding is that it can come in quick, but it can also go quick so it's unlikely it will be there for a full day.
"We have concerns when the smoke is around because it is a challenge on those two metrics: visibility and breathing."
NSW spinner Steve O'Keefe said being out on the field during a recent smoke-affected Sheffield Shield game at the SCG was like "smoking 80 cigarettes a day".
"The one thing they need to look at is the air-quality policy," O'Keefe said. "That was shocking. I don't have kids, but if I did they'd be locked up inside, and if I was at home I wouldn't be training or playing in it.
"That air quality was shocking. The doctor was all over it and speaking to us about it, and the fact the game wasn't going to go all day was considered, but in the future they need to look at it because it's not healthy — it's toxic."