Build Your Sensor :: The Sensor Project

Build your sensor

Why build your own air quality sensor?

Air pollution poses a great concern to human health and the health of the environment. Air pollutants most commonly impact the respiratory and cardiovascular systems and can, for example, increase the risk of developing lung cancer or experiencing a heart attack. Individuals with existing conditions are particularly sensitive to the adverse effects of air pollution.

To protect human and environmental health, international and national health agencies have published set safe limits for air pollutant levels. In order to ensure these limits are maintained, governments sometimes establish stations with high-grade air quality sensors that monitor pollutant levels in cities. However, this method of monitoring cannot account for localized fluctuations in air pollutant levels throughout a city. As a result, the air pollutant levels measured by governmental monitoring stations may not be representative of the air quality a citizen experiences in daily life.

This project will provide you with the knowledge to use portable, low-cost sensors to monitor your own air quality. All citizens, regardless of training, should be able to access and be able to understand important air quality data. The pollutants targeted by this project are particulate matter (PM_2.5) and nitrogen oxides (NO_x). The levels of each of these pollutants can be monitored by building a simple sensor. Necessary materials for each sensor can be easily ordered online, and then put together using the instructions found here.

Particulate matter (PM_2.5)

Particular matter refers to a complex mix of tiny solid and liquid particles in the air, such as dust, dirt, soot, and smoke. Since the chemical composition can vary, particulate matter is classified by size (PM_2.5 consists of particles with a diameter of 2.5µm or less). These particles are so fine that they can get deeply embedded in the lungs and pass into the bloodstream. Together, many particles can be visualized as smoke or soot. Sources include vehicle exhaust, forest fires and coal-burning power plants.

Nitrogen oxides (NOx)

Nitrogen oxides are part of the characteristic brown smog that can form a covering over cities. Nitrogen oxides can form when nitrogen and oxygen react at high temperatures. Naturally, this can occur in lightning storms; however, most nitrogen oxides form in vehicle engines and industrial furnaces. Nitrogen dioxide can dissolve in moisture in the lungs to form an acid, which can cause various types of respiratory and cardiovascular complications.

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