This week, South Korea will fly a military plane to Australia to airlift 27,000 litres of urea solution, also known as diesel exhaust fluid (DEF), as the country experiences a shortage crisis of the liquid after China dramatically cut its urea exports. Diesel vehicle drivers, particularly truck drivers, have been waiting in long queues to refill fuel, concerned about the supply crisis. Urea is the main component of DEF, an additive used in diesel vehicles to reduce emissions. In South Korea, DEF is not only mandatory for air quality control purposes and essential for the proper operation of diesel vehicles sold after January 2015. About 4 million diesel vehicles in South Korea need urea to operate. Among them, two million are trucks, which means that the shortage of automotive urea has sent the country’s transport industry into chaos. “I drove about 70 kilometres to a gas station to just get …