Linking Today into Tomorrow
The effects of air pollution can be immediate or be slow to emerge, be short-term or last for generations, be local or be found long distances from pollution sources.
Unfortunately, this diversity can complicate and confuse our ability to recognize the linkages between our actions, the current environmental conditions, and what may happen in the future.
If we don't recognize and appreciate these linkages, it is difficult to balance the importance of making everyday choices to take action to reduce air pollution with daily life activities such as getting to work.
Smog and acid rain
Pollutants that degrade local and regional air quality, such as those that contribute to smog and acid rain, generally cycle out of the local atmosphere in less than a week depending on weather conditions. This means that air quality concerns persist, repeat and often get worse because our emission-causing activities also persist and repeat. As a result, there is an opportunity to see relatively immediate improvements in air quality by changing our activities.
Still, quick improvements may not always be possible as a history of exposure to air pollution, or even short-term exposure at high concentrations, can have lingering and potentially permanent effects on human health, the environment and the economy.
Persistent organic pollutants (POPs), heavy metals and toxics
Other pollutants such as persistent organic pollutants (POPs), heavy metals and many toxics have long-term impacts on the environment and can travel great distances.
For example, POPs move northwards in a process called the grasshopper effect, from the warmer parts of North America to the colder regions of the Arctic where they collect.
These pollutants are slow to chemically breakdown, and so our exposure to these pollutants can last for long periods of time (i.e. potentially hundreds of years).
The impacts of these pollutants can be immediate and severe because they are toxic and can enter the food supply through other animals, as well as fruits and vegetables. Once they're in the food supply, they can collect in animal fat, bones and tissues, and get passed on to whoever consumes these animals. This is known as bioaccumulation and a particular concern for top-level predators.
Climate change
Climate change presents a number of challenges to linking our actions to their impact on human health, the environment and the economy.
The first challenge is that greenhouse gases have their most immediate impact within the global atmosphere – they are well mixed in the atmosphere, so that it does not matter where they are emitted.
These gases can remain in the atmosphere for decades to hundreds, or in some cases, thousands of years. So, even if we reduce or eliminate emissions today, climate change concerns will persist for many years to come.
Finally, the impacts of climate change on the environment may be so subtle that they are difficult to recognize and point to its impact. For example, we expect more extreme weather events due to climate change but it’s not possible to point to one storm and say that it was caused by climate change.
Stratospheric ozone depletion
Depletion of the ozone layer in the earth's upper atmosphere is a global issue. Scientists first raised concerns about the ozone layer in the early 1970s. However, it was the discovery of the Antarctic ozone "hole" in 1985, which brought the issue international attention. The ozone "hole", which appears regularly each spring over the South Pole, is actually a large depleted area, where up to 70% of the ozone is lost. In recent years the hole has covered most of the Antarctic continent and has extended over populated areas at the tip of South America. Over the Arctic, ozone depletion is not as severe. In some years, ozone loss over the Arctic can be quite extensive, with up depletions of up to 40% in the late winter and early spring. Yet in other years, Arctic ozone can be close to normal. Over southern Canada, the ozone layer is an about four percent thinner than normal, with greater losses of about six to eight percent in the early spring.
Despite considerable action to protect the ozone layer, scientists have yet to see any clear evidence of recovery. Industrial chemicals, such as CFC's, are the major cause of ozone thinning, and the build-up of the most significant CFCs in the lower atmosphere has now ended. One of the key chemicals (CFC-11) is even decreasing. However, these chemicals account for only about half of the ozone loss in the Arctic. Scientists suspect that climate change may be responsible for the cooling of the upper atmosphere, leading to increased depletion in the ozone layer.
