rizgard, qobâr-e nâzok
Fr.: poussière fine
Meteorology: An → inhomogeneous → mixture of tiny, part → solid, part → liquid or → gaseous → particles that are, in average, smaller than ten → microns. The constituents are soot, heavy metals, organic substances, and dioxins. The smaller these dust particles, the deeper they penetrate into the lung. Larger particles are intercepted by mucous membrane in nose, mouth, and throat but smaller particles can penetrate the smallest lung bronchioles and may cause severe damage (various respiratory disorders, lung cancer) → particulate matter.