### Instruction: Extract the ways the asthma is classified and create a bulleted list.
### Input: Asthma is thought to be caused by a combination of genetic and environmental factors. Environmental factors include exposure to air pollution and allergens. Other potential triggers include medications such as aspirin and beta blockers. Diagnosis is usually based on the pattern of symptoms, response to therapy over time, and spirometry lung function testing. Asthma is classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate. It may also be classified as atopic or non-atopic, where atopy refers to a predisposition toward developing a type 1 hypersensitivity reaction.
https://en.wikipedia.org/wiki/Asthma
### Response: -Frequency of symptoms
-FEV1
-Peak expiratory flow rate
-Atopic
-Non-atopic