Welcome Salma
I think you need to be more specific.
- an Arduino device that samples air pollution; is it something like this DIY Air Quality Monitor - PM2.5, CO2, VOC, Ozone, Temp & Hum Arduino Meter
When your phone goes to sleep it will not be able to automatically make a call unless you use a background extension.
Possible if you have excellent Arduino and App Inventor coding skills. You might use Open Source • Background Tasks: Itoo and need to send an sms (text0 message instead of an actual phone call.
A simple App Inventor air pollution monitor not using Arduino might be useful.