![]() The most recent evidence from the Government’s Committee on the Medical Effects of Air Pollution (COMEAP) suggests that some 29,000 deaths per year (4,000 in London alone) are brought forward by exposure to man-made particulate air pollution at current levels.īoth the size and composition of the particles, and length of time of exposure, determine any potential health effect. Particle pollution <2.5µm diameter comes mainly from vehicles, and is responsible for elevated levels during pollution episodes, and is therefore associated with health effects. Those between 4µm and 10µm diameter are trapped by mucus in the airways, and those less than 4µm can reach deep into the air sacs in the lungs. However, the very tiny particles that reach deep into the lung may be absorbed into the blood stream or cause lung problems. Larger particles reaching the nose or throat will be filtered out by the body’s natural defence system. Particles can cause irritation to the eyes, nose and throat. Assessing the exact makeup of particles in air is complex, however, as they are monitored either by size or composition. Along with size, the composition of particles in air will determine any health effects they have. In urban air, particles come from many sources. Large size means the atmospheric lifetime is short.
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