The layer of gases surrounding the Earth: it filters out most of the sun's UV rays and it serves as a storehouse for gases that comprise air.

A colourless, odourless gas, one of the most important of the greenhouse gases and essential to plant life on Earth.

Human-made chemicals that create holes in the atmospheric ozone layer.

Results from the greenhouse effect and will cause major disruptions in various ecosystems around the world.

An increase in the average temperature of the Earth's surface in response to an increase in emission and greenhouse gases.

The insulating effect produced by gases in the Earth's atmosphere. It traps radiant heat and warms the planet.

Formed by a reaction between nitrogen oxides and volatile organic compounds in the presence of sunlight. Levels have been greatly increased by human activities such as the burning of fossil fuels.

A deadly gas byproduct of the breakdown of organic material - high concentrations found in garbage dumps. It contributes to the erosion of the ozone layer.

A gas layer in the upper atmosphere that acts as a natural filter blocking UV rays from the sun.

Fine dust and soot particles from natural and human-made sources such as industrial activity, fossil fuel combustion, agriculture, fires etc.

A discoloured haze that is a combination of airborne particles, gases, and chemicals (ground-level ozone) that together affect our health and our natural environment.

VOCs are a major cause of ground-level ozone as a result of their chemical reaction with sunlight. They come mainly from fuel combustion and from the evaporation of liquid fuels and solvents.