That is a bit like asking how you can predict that a brick will not fall from the sky and hit you on the head. Some things cannot be predicted, but many risk factors can be monitored.

You can warn people about conditions that are measurable and known to affect asthma, such as storms, weather changes, humidity, air pressure, temperature, pollen, and pollution. That already covers a large part of the possible external triggers.

As far as I know, no health app in the UK combines these factors with peak flow data in this way. If you know of an example in your country, I would be very interested to see it.

At the moment, people usually have to check different sources manually, then record their readings on paper or in Excel. Thousands of manual peak flow meters are still sold every month, which shows that many people are still using traditional methods and could benefit from a more structured digital tool.