A substance or material that causes pollution is called a pollutant. Pollutants can be categorised into three types: air pollutants, water pollutants and land pollutants. Air pollutants can be gases or particles that can cause health problems when inhaled, such as smoke from factories, fumes from vehicles, and dust from construction sites. Water pollutants are substances that can contaminate water sources, such as sewage, fertilisers, and chemicals from industrial processes. Land pollutants can be solid wastes, such as plastics, metals, and electronic waste, that can accumulate and harm the environment.