Unmanned air vehicles (UAV) could be the future of air pollution measurements

SOURCE: Cárdenas, A.; Rivera, L.; Gómez, B.; Valencia, G.; Acosta, H.; Correa, J. (2018). Short Communication: Pollution-and-greenhouse gases measurement system. Measurement, 129: 565-568. https://doi.org/10.1016/j.measurement.2018.07.039

WHAT IS AIR POLLUTION?

Earth’s atmosphere is quickly becoming polluted due to human activity.  The concentrations of greenhouse gases, pollutant gases, and aerosols have all increased since the Industrial Revolution. Let’s introduce a few of these culprits. Greenhouse gases, such as carbon dioxide, methane, and nitrous oxide, trap heat in the atmosphere, causing a rise in Earth’s temperature.  They are produced by cars and power plants, among other sources. Pollutant gases, including carbon monoxide, sulfur dioxide, and nitrogen dioxide, are produced from burning fossil fuels.  Aerosols, on the other hands, are solids: tiny particles that reduce visibility by scattering and absorbing light in the atmosphere.  Human-made aerosols are produced by burning coal and oil.

Altogether, these gases and solids move through the atmosphere and impact Earth’s climate. And not just the climate:  human health, too.

NEW TECHNOLOGY MIGHT BE ABLE TO HELP

One of the most common methods used to measure the concentrations of gases and pollutants in the atmosphere is a network of towers containing sensors.  These allow scientists to collect local data, but not determine regional and global conditions.

Recent technological advancements have led to the use of unmanned air vehicles (UAV), such as drones, to monitor air pollution.  For example, one team from Australia designed a solar-powered UAV able to measure greenhouse gases from agricultural farms (Rojas et al. 2015).  However, there is a need for a system that can carry more weight, measure more variables, and communicate in real time.

THE NEW SYSTEM

In a recent study, Andrés Cárdenas and his colleagues from the Universidad de San Buenaventura and the Universidad de Medellin in Colombia developed a new device – another UAV – that could be used for air quality monitoring.  The system can measure 17 different variables, including concentrations of several different greenhouse gases (i.e. carbon dioxide and methane), the amount of particulate matter, temperature, and GPS position, among others.

The system itself has three compartments:  a lower compartment containing the atmospheric sensors, a dust sensor, a battery, a data processing board and the communication systems; a middle compartment contains all gas sensors; and a top compartment with a carbon fiber coupling connecting it to the UAV.  Amazingly, T=the system is lightweight and only weighs 2.6 pounds (1.18 kg).

The researchers tested the prototype system in two UAVs.  First, they attached the system to a hexacopter (Figure 1) and flew it over a parking lot at the University of San Buenaventura in Colombia.  The flight lasted 20 minutes and flew at a height of 328 feet (100 meters).  Next, they attached the system to an unmanned airplane in Envigado, Columbia.  The flight lasted about 30 minutes and the UAV traveled 4.3 miles.  The typical battery life of a drone is 20 – 30 minutes, limiting the flight time that can currently be accomplished.

Figure 1. Example of a Hexacopter (not the one used in this study). Image Credit: Alexander Glinz, Wikimedia Commons.
DID IT WORK?

The prototype system designed by the scientists was able to successfully collect measurements during both trial runs.  The system minimized the size and maximized the mobility of the measuring equipment.  Compared to other aerial vehicle proposals, it is smaller in size and weight, can measure multiple variables simultaneously and is, of course, mobile, versatile, and autonomous.

However, there are some limitations with using UAVs for research.  The flight time is limited due to the battery life.  Also, regulations in the U.S. can limit where and how high drones can be flown.

However, the new system offers promise because it can be attached to different types of aircrafts, allowing measurements of larger areas, allowing scientists to determine how polluting gases interact in the atmosphere with different climatic variables and at different heights.

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Elizabeth Brannon

I recently graduated with a Ph.D. in Biology and Environmental Science from the University of Rhode Island where I studied greenhouse gas emissions from wastewater treatment. I am committed to developing a better understanding of the impacts we have as humans on the planet. I'm a hard core New England sports fan and when I'm not cheering on the Patriots you can find me outside on an adventure!

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