Dust

Dust (also called dust particles or fine dust) consists of tiny solid particles made up of soil, sand, water-free particles, and other natural or human-made substances. Their small size allows them to be carried by air and remain suspended in the atmosphere for a period before settling on the ground or surfaces inside buildings.

Dust can originate from any degradable solid material: barren soil, ploughed fields, unpaved roads, demolished structures, as well as shed skin, animal hair, and human dander. For this reason, indoor dust differs from outdoor dust.

Types and sizes

Atmospheric dust science is defined by examining the size of particles. Particles smaller than 10 microns (known as PM10) can reach the respiratory passages, while those smaller than 2.5 microns (PM2.5) penetrate the lower sections of the lungs. Large particles fall quickly, while small particles can remain in the air for days and travel hundreds of kilometres.

Dust storms

When strong winds arise from barren, unvegetated soil, large amounts of dust are lifted into the air to form dust storms. This type typically originates from desert areas and semi-arid regions, such as the Sahara Desert and East Africa. Saharan dust travels through the air across the Atlantic Ocean. Dust storms reduce visibility, disrupt travel, and can bury crops.

Health and climate

Inhaling large amounts of dust can worsen respiratory diseases such as asthma and bronchitis, and can aggravate heart and cardiovascular conditions. Work involving high dust levels, such as excavation, stone cutting, and construction, presents particular risk when the dust contains silica, which can cause a lung disease called silicosis. Climatically, dust particles reduce solar radiation and affect global temperature, and play a role in cloud formation and water recycling in the atmosphere.

Ecological benefits

Dust is not only harmful. It carries minerals such as iron and phosphorus, which nourish marine and distant land ecosystems. A notable example is Saharan dust that falls on the Amazon rainforest, enriching its soil nutrients.

Reduction

Common methods of reducing dust include watering unpaved roads, planting vegetation to prevent wind carrying soil, covering construction materials, and installing filters in factories. Indoors, regular cleaning and good ventilation reduce dust inhalation.