Causes, Triggers & Risk Factors
Time of year - Winter seems to be a more troublesome time of year for asthma sufferers as exercise-induced asthma is more likely to develop outdoors in cold weather. Also because viral respiratory infections such as colds are more common in winter.

Smoking - Smoking can tend to trigger asthma especially in children. People are encourage to not smoke around asthma suffers, particularly children.

Exercise - Exercise can trigger asthma especially with children in the pre-school years.

Rees, John, 1949, ABC of ASthma, Chichester, West Sussex, UK ; Hoboken, NJ : Wiley-Blackwell ; [London] : BMJ Books, 2010. 6th ed.

Obesity - conditions linked to obesity may affect airway function and increase the possibility of developing asthma

Gender - Asthma is more common in boys than in girls in childhood years. However, more females develop asthma during and after puberty. This means that more adult females have asthma than adult males.

Diet - Infants who are breast fed generally have lower incidences of asthma-like symptoms compared to infants who are fed formula. The large amount of processed foods consumed particularly in western society and the decrease in the intake of fruits and vegetables has contributed to increases in asthma cases.

Allergens - There is evidence that house dust mites, cat and dog hair and mould can trigger asthma-like symptoms, particularly in children up to three years old. However the severity can depend on the allergen, the dose, the time of exposure, the child’s age, and possibly genetics.

Infections - It is possible for children who experience respiratory infections in early years to develop asthma in later childhood.

Kritikos, Vicky (2007) Innovative Asthma Management by Community Pharmacists in Austrtalia , 2007.