A thick blanket of smoke rolled into Bathurst on Wednesday night and while some cleared overnight, the air quality index in the city at 9am on Thursday still remained hazardous, with a reading of 223.

It was the second time in just four days health professionals have issued warnings regarding the quality of the air.

On Monday, Bathurst was again clouded in smoke from fires burning north of Lithgow, in this instance an air quality alert was issued for residents in Central NSW due to smoke from the Gospers Mountain fire which was burning out of control in the Wollemi National Park.

The Western NSW Local Health District reminded people to be vigilant about their health, amidst concernts about ongoing air quality, as fires continue to burn in t he region.

Public health manager Priscilla Stanley said the fine particles in smoke can irritate the respiratory system and aggravate existing lung and heart conditions.

"For most people, smoke causes mild symptoms like sore eyes, nose and throat. However, people with conditions like asthma, emphysema and angina are more likely to be sensitive to the health effects of smoke," Ms Stanley said.

"People with these conditions should avoid outdoor physical activity when there's smoke around."

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Ms Stanley said those with asthma should follow their Asthma Action Plan and have their relieving medication with them and in case of emergency always remember to dial Triple Zero.

Following the drop in air quality over the last two weeks, pharmacies in the region have also seen a run on Ventolin as well as over the counter remedies to control hay fever.

Steven Yiv, a pharmacist with John Matthews Chemworld Chemist, said they had seen an increase in demand for not only Ventolin, but also over the counter remedies for hay fever, especially when the dust storm hit Bathurst last Tuesday.

"We've had a few people come in and say they were having trouble breathing and their chest was feeling quite constricted," he said.

Mr Yiv said for hay fever there were a number of over the counter medications available.