Flyash pollution is caused by

Fly ash is a fine, powdery byproduct generated during the combustion of pulverized coal. The primary source of fly ash pollution is thermal power plants. When coal is burned to produce electricity, the non-combustible mineral matter is carried away by flue gases as fly ash.

Fly ash contains various toxic heavy metals such as arsenic, lead, mercury, and cadmium, along with silica and alumina. If not effectively captured by electrostatic precipitators (ESPs) or bag filters, it causes significant air pollution. It can also lead to water and soil contamination when stored in ash ponds. While other industries like cement or steel may use coal, the scale of coal consumption in thermal power generation makes it the dominant contributor to fly ash pollution.