Mohammed Nihal's Acid Rain Forecasting System Uses Local Sensors to Deliver a Risk Rating
Gas sensors for hydrogen sulfide and nitrogen dioxide combine with temperature and humidity readings for a "risk score."
Maker Mohammed Nihal has built a desktop environmental monitor that aims to use locally-gathered sensor data to predict the likelihood of acid rainfall.
"Acid rain forms when harmful air pollutants like Sulfur Dioxide (SO₂) and Nitrogen Dioxide (NO₂) combine with moisture in the atmosphere," Nihal explains. "This project predicts the chances of acid rain before it occurs by monitoring SO₂, NO₂, humidity, and temperature in real time."
Rather than relying on remote monitoring stations which may be too sparsely spread for accurate local forecasting, Nihal's acid rain alert is based on data from on-board sensors: an MQ-136 gas sensor tracks hydrogen sulfide concentration, a second sensor tracks nitrogen dioxide concentration, and a classic DHT11 is used to monitor temperature and humidity.
Data from each of the sensors, installed in a 3D-printed chassis designed to resemble a cloud, is processed by an Arduino Nano microcontroller board and an "Acid Rain Risk Score" is derived. A 16×2 LCD panel on the front provides at-a-glance readouts of this score — and lets you know if the washing you just hung out to dry is likely to dissolve.
The project is documented in full, including source code, on Instructables. "Let the MQ-136 sensor warm up for 2–5 minutes," Nihal advises anyone interested in building their own, "for stable readings."