In this case study exercise, students are asked to research on the followings
1.The nature and working principles of air ionizers
2.The applications of air ionizers in indoor environment and protection for human exposure
3.The effectiveness of air ionizers and corresponding evaluation methodologies
4.The side effect of air ionizers
5.The performance of ionizers comparing to traditional filter type air purifiers
6.Comment on how commercial ionizers shall be applied and claimed upon their performance.