So to get into a human's lungs, they have to ride on mold spores or dust particles.
Although this is a small sample, it suggests that man-made dust particles predominate over naturally occurring ones.
So, too, says Sengupta, is silicosis, tuberculosis and bronchitis from inhaling dust particles.
So, too, says Sengupta, are silicosis, tuberculosis and bronchitis from inhaling dust particles.
But Dr Bill Sammons said people living near the plants could be at risk of harm from breathing in dust particles.
Levels of nitrogen dioxide and fine dust particles emitted will be analysed.
The inhalation of these fine dust particles represents a health hazard that was known to the military as long ago as 1974.
Heavy, gritty particles seem to be sitting at around 8, 000ft (2440m) , while lower down in the atmosphere there are sulphurous chemicals and finer dust particles.
BBC: Flight ban 'not over-reacting' say Wiltshire scientists
Matt Loxham, a medical biologist at Southampton University, collected minute dust particles of different sizes from at an underground train system in an unnamed European city.
At the same time, the experiment's clever design makes it possible to distinguish between man-made and naturally occurring dust particles, and so determine their relative proportions.
In all, it recorded 159 impacts, which is broadly in line with the predictions made by the models for the number of dust particles that are 850km up.
The enormous shroud of fine mineral dust particles now stretches from the Arctic Circle in the north to the French Mediterranean coast in the south, and from Spain into Russia.
Before people started making such a mess, the number of dust particles orbiting earth was tiny, since they would have been dragged quickly into the atmosphere by friction and burnt up.
Wear a filtering mask when cleaning to avoid inhaling dust or airborne particles from cleaning products.
The danger from nuclear waste comes mainly from dust-like particles containing radioactive isotopes of iodine, cesium and strontium that could be released if the reactor fuel is allowed to become too hot.
They also conclude that greenhouse warming has partially been offset by the cooling effect of aerosols - tiny particles of dust thrown into the atmosphere that can reflect solar radiation back into space.
Earth is bombarded with more than 100 tons of dust and sand-sized particles every day, much of it falling into the oceans or remote areas, and otherwise going unnoticed.
Collisions between the cosmic rays and the slower-moving protons that exist in the gas and the dust around a supernova should produce subatomic particles called neutral pions.
The lung tissue reacts to the dust by developing nodules and scarring around the trapped silica particles.
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