Industrial agriculture is the problem. Pesticides are supposed to destroy undesirable bugs, but this is far from a precise process. Pesticides kill all life in the soil. Industrial farmers then need to use chemical fertilizers to replace the lost nutrients. This further depletes the soil, and shatters its ability to hold water.
Rainfall soon washes it away.
100 million acres of U.S. cropland have thus been degraded by soil erosion. This cannot go on. Sprayed from planes, or blown in the wind, the poisons are airborne, and we breathe them. The problem gets worse every year, as bugs become immune. They require more poison for the same result.