A coroner has ruled that a Christchurch woman died as a result of Legionnaires' disease, which she caught from working with potting mix.
Margaret Velenski died in her sleep on Boxing Day 2011 from bronchopneumonia.
It was initially thought she had a lung infection, but after a post mortem it was found she had contracted a form of Legionella which led to bronchopneumonia.
Coroner RG McElrea says the 63-year-old, who was an avid gardener, contracted the infection while working with potting mix.
Mr McElrea referred to comments from the Medical Officer of Health that health authorities usually see a spike of legionnaires cases in spring.
Some 80% of those cases involve people who have dealt with potting mix or compost prior to infection.
Health warning
The Canterbury Medical Officer of Health is warning people to avoid inhaling dust from potting mix and compost when gardening.
Dr Ramon Pink says legionella thrives in moist, dark and enclosed soils and when bags of them are opened, the dust becomes a vehicle for inhaling it.
He says health authorities see a spike in Legionella cases in spring and summer and most of these are gardening related.
"We love getting out into our gardens and it's important just to beware of this bug that can cause illness and tragically for some people fatality."
Dr Pink says gardeners should open soils outside and wear a face mask and gloves when using them.