This is somewhat similar to the hunt I've seen few days ago

Pros:

• Perfect for people who are experiencing respiratory issues. This could help them stay away from polluted places
• This may also be helpful to enviromentalists who asses the quality of air in several areas in order to apply some corrective measures
• Very handy and can be brought anywhere. Data could also be readily availble in our smartphones thru an app

Cons:

• I assume it will need some data connecitivity in order to assess the air quality using the app. In cases like connectivity is very low, this device will also be useless.