Breathing Hong Kong's toxic cocktail of pollutants makes us stupid
Toxic heavy metals in the air have huge effect on our bodies and characters, even years after we leave highly polluted environments
Everyone knows that in Hong Kong we don't breathe air any more but a chemical soup which is bad for us. But understanding how it harms us requires the multidisciplinary skills of geologists, biologists, chemists and psychologists. Heavy metals, the most dangerously toxic pollutants, have resided undisturbed in the earth's crust since its formation five billion years ago. They came from first-generation exploded star debris.
During the first four billion years of life's evolution, only very small amounts of these elements found their way into the biosphere through volcanic eruption or leaching of rocks. Life emerged in a chemical soup largely lacking heavy metals, so most species failed to develop high levels of tolerance.
However, in the last 200 years, mining of coal and other minerals, together with oil drilling and manufacturing, released large amounts of heavy metals into our biosphere with results which scientists are only now beginning to understand.
Scientists have monitored our air and discovered a cocktail of toxic chemicals, each damaging us in a different way. The most damaging are heavy metals attached to PM2.5 particles of dust which are so small they can float right through our cell walls when we inhale them, lodging in our lungs, brain and other organs.
The most common heavy metal in our environment is lead, which can be found almost everywhere: in our air, water, paint, electric storage batteries, insecticides, car body shops, petrol, toys and seafood. It can have a dizzying number of effects on our bodies, including decreased intelligence and learning difficulties and attention deficit disorder. It can also impair our speech and cause violent behaviour, poor muscle coordination, decreased muscle and bone growth and kidney and hearing damage.
Other common toxic heavy metals include mercury, cadmium and zinc, which can alter our DNA. They are released by coal-burning power stations, ships and factories. The wind can carry them hundreds of kilometres.