Shocking conditions at a smoke-blanketed SCG affected the vision and breathing of cricketers from NSW and Queensland on Tuesday, prompting Steve O'Keefe to call on Cricket Australia to ensure the scenes are never repeated.

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O'Keefe helped the Blues extend their unbeaten start to the Sheffield Shield season, grabbing 3-28 as the table-toppers rolled the Bulls for 176 and made light work of their target of 42.

However, bushfire smoke at the iconic venue proved as big a talking point as the on-field action on day four of NSW's nine-wicket victory.

Queensland skipper Usman Khawaja felt like he was batting in New Delhi during a knock of 54, noting it was "hard to breathe" and the haze affected players' vision.

NSW captain Peter Nevill agreed the smoke "significantly altered visibility".

Blues spinner O'Keefe declared he has never played in worse conditions at any cricket ground in the world.

"For someone like me who smokes 40 a day, it's now smoking 80 cigarettes a day," the 35-year-old quipped.

"The one thing they need to look at is the air-quality policy.

"It's not healthy. It's toxic … 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.

Matthew Gilkes (number 99) did well to hold on to this catch as the ball flew through the smoke. ( AAP: Craig Golding )

"I'm sure they'll address it."

NSW Health has urged Sydney residents to cut back on outdoor physical activity because of the smoke.

Air quality regularly affects cricket games in New Delhi, most notably in 2017 when players donned face masks and some left the field to vomit during a Test.

The start of a recent second XI game in Sydney's west was delayed because of smoke but the relevant Air Quality Index (AQI) was more concerning in that case.

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AQI readings were monitored throughout Tuesday but the number was never high enough to stop play.

Khawaja consulted the players' union on Monday and Cricket Australia medico John Orchard, who was at the SCG, on Tuesday morning.

"There were limitations there. If it got really bad … we probably would have come off," Khawaja said.

"I've never played in anything like that in Australia.

"It was bad but it wasn't unplayable … I wasn't going to use that as an excuse to come off and make a fuss about it, or say it's unsafe."

Khawaja added one run to his overnight score, having produced his first half-century of the Shield season.

"I've felt really good … I scored a lot of runs in the white-ball stuff, haven't scored as many runs in the red-ball stuff," the Test discard said.

AAP