What is the yardstick for measuring pollution?
It is called RSPM, or Respirable Suspended Particulate Matter, and is made up of dust, soot or smoke particles. Their tiny size makes it virtually impossible to filter them out. These solid and liquid particles are less than 10 microns in diameter. To put that in perspective, a strand of human hair is between 50 and 70 microns thick. RSPM is generally classified as PM10 (diameter 10-2.5 microns) and PM2.5 (under 2.5 microns).
Where does it come from?
From organic and inorganic sources such as vehicular exhaust and dust from construction, stone-crushing and grinding, and paved roads.
How is RSPM harmful?
The lungs and the air passage are the first organs affected. The smaller the particles, the deeper they enter the lungs. While PM10 affects the upper respiratory tract from the nose and windpipe, the smaller PM2.5 affects the lower respiratory system. RSPM worsens existing respiratory problems such as asthma and bronchial diseases. It is especially harmful for children, the elderly and pregnant women. International research has linked RSPM to almost all organs, including the kidneys and the brain — it contributes significantly to lung cancer, and affects foetal development in pregnant women.
What else pollutes besides RSPM?
Ozone: Ground-level ozone is among the primary components of photochemical smog, with the highest levels likely in summer. Released from vehicular exhaust, industrial emission and chemical solvents, ground-level ozone can cause respiratory problems.
Nitrogen dioxide: It is the main source of nitrate aerosols, which in turn form an important part of PM2.5. This mixture when exposed to ultraviolet light contributes to the release of ozone. Emissions from cars, trucks, power generation plants and off-road equipment are common sources of this gas, which can contribute to acid rain.
Carbon monoxide: Among the more hazardous emissions from internal combustion engines, it is particularly high in areas where slow-moving or stationary traffic is higher. It is part of the cycle that eventually leads to photochemical smog. It reacts with haemoglobin in the blood, reducing its capacity to carry oxygen.
Sulphur dioxide: It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulphur. When combined with water vapour, it forms sulphuric acid, a primary component in acid rain. Corrosive to the skin and eyes, it can also lead to death if inhaled.
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