Port Hills' residents affected by this week's wildfires - now under police investigation - are being reassured the smell of smoke in their properties poses no serious threat to health.
Canterbury Medical Officer of Health, Dr Alistair Humphrey, said those returning to their homes will notice a strong smoky smell.
"While [they] ... may find the smell distressing, it presents no immediate harm to health."
Health effects from smoke usually occurred at the time of exposure, Humphrey said.
"Most people are very unlikely to have any long-term health effects from short-term exposure to smoke but people with pre-existing respiratory (lung) illness or heart disease may experience and exacerbation (recurrence) of their condition."
Two people had sought help at Christchurch Hospital's emergency department for breathing problems exacerbated from smoke during the fires.
Anyone with health issues following the fires should contact their GP team for #carearoundtheclock 24/7, he said.
Canterbury had faced its share of disasters this decade and many people would understandably be feeling overwhelmed and in shock.
"We all need to remember to look out for one another and take care of each other."
All Right? manager Sue Turner said it was normal to feel shaky, queasy or on-edge, have trouble concentrating, or cry or get angry after a disaster.
Distress could be eased with light physical activity, taking up a small chore or task and by focusing on calm breathing for 10 seconds. It was also important to ask for help when needed.
Meanwhile, Detective Inspector Greg Murton said no definitive cause for either of the Port Hills' fires had been established.
The fire service is investigating the cause of the fires, and while there had been speculation about the cause, it remained unknown.
