New
environmental analysis has revealed that visibility on clear days has declined since the 1970s due to a rise in pollutants in the air.
This 'global dimming' is most prominent over south and east Asia, South America, Australia and Africa, researchers from the Universities of Maryland and Texas have stated.
Meanwhile, visibility in the air above North America remained stable while it has improved over Europe.
The dimming is being caused by increasing numbers of aerosols which are tiny particles or liquid droplets being pumped into the air by the burning of fossil fuels and other resources.
One of the researchers, Robert Dickinson from the University of Texas, said: "Aerosols are going up over a lot of the world, especially Asia."
Kenneth Mukamal, a managing director at Beth Israel Deaconess Medical Centre and Harvard Medical School in Boston, recently explained that a recent investigation failed to show an association between
air quality and an increased risk of headaches.