Complex sentence: During hot summer weather passengers are warned against using the emergency alarms if feeling unwell, since it can delay trains and increase the problem; they are instead instructed to leave the train at the next station and get some fresh air or a cold drink.
Split into simpler sentences: During hot summers passengers are warned against using the emergency alarms if feeling unwell, since it can delay trains and increase the problem. Passengers are instead instructed to leave the train at the next station and get fresh air or a cold drink.