“VULNERABLE” Darwin residents are being urged to stay indoors with their windows closed and to avoid excessive exercise and unnecessary activity over the long weekend because of deteriorating air quality.

NT chief health officer Dr Hugh Heggie said a lack of wind, high humidity and fog was influencing the air condition.

Dr Heggie said the particles in the air was caused by biomass burning as vegetation was set alight for land clearing.

“It’s the size of the particles that can irritate your nose and throat,” he said.

“If you are feeling distressed with your breathlessness, you should call 000.”

The current hazy conditions in and around Darwin are expected to continue over the next few days and are a combination of fog and smoke particles in the air.

Dr Heggie said the smog may not clear until early next week.

“That’s when we expect some drier air in the north, and the humidity to drop,” he said.

As there are no significant winds forecast for this weekend, the Top End can expect the same combination of moisture and smoke particles to persist for the next few days.

The young, elderly and those with known lung diseasees, including asthma, are particularly vulnerable, Dr Heggie said.

However people with underlying conditions, including heart disease, cancer and chronic conditions, should also take take.