Date of Award


Document Type



Santa Clara : Santa Clara University, 2018.


Computer Engineering; Electrical Engineering

First Advisor

Shoba Krishnan

Second Advisor

Behnam Dezfouli


Urban air pollution leads to widespread respiratory illness and millions of deaths annually. PM2.5, particulate matter with a diameter less than 2.5 micrometers, is the product of many common combustion reactions and poses a particularly serious health risk. Its small size allows it to penetrate deep into the lungs and enter the bloodstream. Existing air quality monitors are aimed at scientific research, di↵erentiating between pollutants and providing high accuracy in measurement. These devices are prohibitively expensive and cannot easily be carried around. Due to the highly localized nature of air pollution, and in order to allow individuals and institutions to easily monitor their real-time exposure to PM2.5, we propose Halo, an air quality monitor costing less than $100. Halo is powered by a 500 mW solar panel and equipped with a 1500 mAh Lithium-Ion battery in order to handle 150 mW peak power consumption and operate continuously for over 24 hours without power input. The device is small enough to be clipped to a backpack or bag for easy portability, and it can be used in personal or public settings. Using an IR emitter and detector, Halo measures reflected IR light to determine the particulate concentration in the air with an error less than 10%. It uses Bluetooth Low Energy (BLE) to communicate these values to a user’s phone. From the phone, air data can be time-stamped, stored in a cloud database, and visualized in an app for easy monitoring of pollution trends and pollution exposure. Additionally, the cloud database allows for the aggregation of data from multiple devices to create crowdsourced pollution maps. These maps can be used to pinpoint areas with particularly bad air quality in order to try to make changes to these areas or to help users to know to avoid these areas in possible.