More smoke from the catastrophic Australian bushfires is expected to hit New Zealand on Wednesday and could have damaging health effects.
The fires in rural New South Wales and Queensland are so large that smoke and dust is travelling 4000km across the Tasman to cover our country.
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Fire scientist Grant Pearce says it's causing red skies, amazing sunsets and eerie daytime light conditions. But there're also warnings vulnerable people need to protect themselves.
When will it hit us?
"The next plume is due into New Zealand late Wednesday or Wednesday night, this time generally across the North Island," says NIWA meteorologist Ben Noll.
"The trajectory of any smoke plume depends on the weather features and air flows in the Tasman Sea at the time. It takes approximately 36-48 hours from the time a plume of dust or smoke leaves Australia to reach New Zealand."
An animation from NIWA shows the first of the smoke reaching the South Island early on Wednesday morning before the bulk of it hits the North Island around 7pm.
What are the dangers?
Most of of the smoke to reach to New Zealand will be very high and dilute, however people should still be cautious about their exposure.
"Particulate matter smaller than 2.5 micrometres can make it past our body's natural defences that filter out particles (ie the hairs in our nose) and go deep into our lung tissue and potentially into our bloodstream," says Dr Tara Strand, rural fire research leader at Scion Rural Fire Research Group.
"Long exposure to smoke is not recommended for healthy individuals and sensitive individuals (ie asthmatics) need to monitor their exposure closely even in light smoke."
Noll says people sensitive to fine particulates will want to take extra care by closing windows and not running their air conditioner.
How long will the smoke last?
"As the Australian bushfires continue to burn, plumes of smoke and dust will be continuously dispersed into the atmosphere. This will happen until the fires are put out," Noll says.
"Given the strong winds in the New Zealand region over the next week, no dust or smoke is expected to sit over the country for a prolonged period - each plume generally takes about 12 hours to pass across a given island."