Fine smoke particles are known to affect the human breathing system. The smaller or finer the particles, the deeper they go into the lungs.

These particles can cause a variety of health problems, such as itchy or burning eyes, throat irritation, runny nose and illnesses such as bronchitis, according to acting director of the North Coast Public Health Unit, Greg Bell.

The smoke particles can also aggravate existing lung conditions, such as chronic bronchitis, emphysema and asthma.

Smoke particle levels are likely to be higher outdoors than indoors, so people sensitive to fine particles should limit the time they spend outside.

"People with asthma and other lung conditions should not engage in vigorous exercise and, if possible, they should stay in air-conditioned premises where filtration systems can help to reduce smoke particles in the air," Mr Bell said.

"Symptoms can occur for several days after smoke is inhaled, so people with the chronic respiratory conditions need to be vigilant with their treatment programs.

"If you have asthma or a lung condition and you develop symptoms such as shortness of breath, coughing or wheezing, follow your Asthma or Chronic Obstructive Pulmonary Disease (COPD) Action Plan.

"If symptoms do not settle, seek medical advice. If you are on home oxygen treatment, continue as prescribed and if breathlessness worsens, contact your doctor."

Healthy adults may also feel the effects of fine particles that can irritate the lungs, so it's wise to reschedule or cut back on prolonged or strenuous outdoor activities when smoke levels are high.

Healthy adults generally find that symptoms will clear after the smoke disappears.

With nearly 1,500 hectares of hazard reduction completed and more underway in state forests of the mid north coast, Forestry Corporation of NSW has closed the areas most recently burnt for public safety.

Mick Wilson, Protection Forester for the mid north coast said trees and branches can fall after fire and particular care should be taken in forests where hazard reduction burning has taken place.

"Hazard reduction burning is an important tool in reducing the risk of wildfires in the warmer months," Mr Wilson said.

"Over the last week, trees have fallen over roads and trails.

"This is part of the life-cycle of a forest and fallen trees turn into habitat on the forest floor but we want the public to be careful and stay safe."

Hazard reduction burns are visible on the Fires Near Me app as planned events.