Canberrans are being warned of a potential thunderstorm asthma event in the region on Saturday.
ACT Health said there were elevated pollen levels and the possibility of severe thunderstorms.
"There is also a possibility that raised dust may impact the ACT on Sunday 29 November due to strong and gusty winds," it said in a statement.
"Thunderstorm asthma can be triggered by a combination of high grass pollen levels and a particular type of thunderstorm, which causes some people to develop severe asthma symptoms over a short period of time."
Wetter than usual conditions encouraging grass growth and increased stormy weather have increased the chances of the events this season.
"Not all thunderstorms produce an asthma event, and thunderstorm asthma is a rare event," it said.
"However, people who suffer from hay fever and/or asthma are encouraged to be vigilant over the weekend for any worsening of their condition. People who have been diagnosed with asthma in the past should also be prepared for a thunderstorm asthma event, particularly if they have suffered or continue to suffer from hay fever. Carry a reliever (blue puffer) with you."
It said people should avoid being outside immediately before or during a thunderstorm.
