What is the most troublesome kind of pollution that the world faces now?

Dear Tom,
What is the most troublesome kind of pollution that the world faces now?
— Jimmy Callo, Bensenville
Dear Jimmy,
Of the many kinds of pollution that are occurring, the worst is plastic pollution. Pollution of the atmosphere and the world’s land and water is a huge problem, and some of the pollution is being reduced and even eliminated. Discarded plastic, however, presents a situation with no solutions. It is accumulating in landfills, discarded on land and especially in the oceans.
Plastic came into widespread use in the 1950s, and the rate of production has been increasing drastically, and continues to accelerate. In addition, “microplastic,” plastic that has broken down into tiny pieces as small as a millimeter in size, has become pervasive in the world’s oceans.