Magistrate Janine Lacy found Jason Cutmore, 48, guilty of common assault during his hearing at Wollongong Local Court on Wednesday.

Cutmore denied he "aggressively" coughed in the face of Dimitiros Andrikopoulos on April 27 this year, claiming he "meant to turn away".

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During the hearing, Mr Andrikopoulos said Cutmore became upset when he was asked, upon entering the Burelli Street office, to remove his face mask.

Mr Andrikopoulos said the man kept "carrying on" and was asked to leave by staff.

But instead of walking away, Cutmore kept swearing about 10 metres away from the door.

When Mr Andrikopoulos told him to leave again, he said Cutmore became more aggressive and had his hands clenched by his sides.

"He walked over to me, I thought he was going to hit me, but he came nose-to-nose with me and coughed in my face," Mr Andrikopoulos told the court.

He said the cough, which was aimed directly as his face was "course", "loud" and sounded "forced".

"I felt saliva on my face," Mr Andrikopoulos. "I was a bit worried because of coronavirus. I wasn't protected, my mouth wasn't closed."

"I was stressing."

Mr Andrikopoulos put Cutmore in a headlock and lowered him to the floor while police were called.

Under cross examination, Mr Andrikopoulos denied he had threatened Cutmore and rejected the suggestion he had sweat, not saliva, on his face.

Mr Andrikopoulos' evidence was supported another security guard, Nathan Campbell, who worked on a different floor of the building and was getting a coffee from the lobby at the time of the incident.

Mr Campbell told the court he had a good view of the incident and saw Cutmore open his mouth, cough and project it forward.

Taking the stand on Wednesday, Cutmore admitted he was upset and "insulted" by having to take off his mask but denied he directed his cough, which he claimed was caused by smoking, at the security guard and instead meant to cough into his arm.

He also disagreed he was was swearing and being aggressive.

Magistrate Lacy said Mr Andrikopoulos' evidence was "honest" and "accurate" and was consistent with Campbell's account.

"I'm satisfied by the version of the complainant, that Mr Cutmore coughed deliberately in his face and in doing so resulted in saliva on his face," she said.

The case was adjourned for sentencing to November 26.

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