A storm front sweeping across New South Wales could trigger serious breathing problems in some people, health authorities have warned.

Thunderstorms are predicted for parts of the state on Tuesday evening, including the north coast and Hunter regions.

They can cause pollen grains to explode and release fine particles which can be inhaled deeply into the lungs, causing people to wheeze and sneeze.

The warnings come after 3600 people presented to hospitals in Melbourne with breathing problems following storms in 2016.

At least nine deaths were linked to the event.

Sydney has never recorded a thunderstorm asthma event of a similar magnitude but rural NSW has, and the health department is urging sensitive people to be extra vigilant.

NSW Health’s Doctor Richard Broome tells Ross Greenwood “it’s all about pollen”.

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