50 Firefighters remain at the scene of a large fire in Woolson.

Fire crews were called to the fire at National Steel on Garlands Rd in Woolston at about 8pm.

Scrap metal including cars remains on fire. A Fire Command Unit is also at the scene.

Large explosions could be heard coming from the yard, with enough force to shake the ground.

Fire Assistant Commander Mike Bowden said 15 fire trucks were at the scene fighting the blaze as of 11.45PM Wednesday.

“We are making progress and knockdowns have proved effective, but this will be a long-duration incident that will continue into Thursday.”

Cordons will remain in place in the immediate area near Cumnor Terrace on Thursday morning, including on Garlands Road and Marshall Street.

The public is being asked to avoid the area and allow firefighters to work safely. People should stay out of the smoke.

Any properties in the vicinity of this area should keep all windows and doors closed.

“We would like to thank the public and surrounding businesses for their co-operation during this time while we fight the fire.

We are working closely with our partners, including Police, Environment Canterbury and Health New Zealand. We’ve also received assistance from the Christchurch Airport Fire Service and we thank them for that.

We have put booms in place on the Heathcote River to attempt to prevent water contamination.

Public health warnings issued

A public health warning has been issued by Christchurch Public Health over the smoke from the fire located at 100 Cumnor Terrace, Woolston.

Medical Officer of Health Dr Matt Reid says exposure to smoke can worsen pre-existing health conditions such as asthma and heart disease.

“Air around this location is smoky and there is potential that people who are sensitive to smoke – such as those with heart or lung conditions, pregnant women, young children and the elderly ­– may experience symptoms like coughing, shortness of breath or eye, nose and throat irritation.

Anyone with health concerns can call Healthline 24/7 on 0800 611 116 for free health advice, or their own family doctor.

People affected by the smoke should close windows and doors, and reduce outdoor exercise.

Industrial sites may store a range of chemicals, as well as produce a range of products. Therefore, if an industrial site has a fire, there can be a large range of pollutants released from the site that may end up in the local environment.

What to do when it’s smoky outside

If you see or smell smoke outside, you should stay inside if it’s safe to do so.

Remember to:

• Keep your windows and doors shut

• Switch your air conditioning to ‘recirculate’

• Air out your house when the smoke clears

• Look out for children, older people, and others at risk

• Keep pets inside with clean water and food. Keep pets’ bedding inside if possible.