28 Nov 2022
Air pollution is a global challenge; needs global solutions
Air pollution travels around the globe and crosses national borders in various forms that are both unseen and seen. Vehicular emissions, air pollution from coal-fired power plants and from factories circle the earth together with vaporised mercury, methane and sulphate aerosols and other airborne toxic chemicals and pesticides. From a health perspective, deaths from toxins […]

Air pollution travels around the globe and crosses national borders in various forms that are both unseen and seen. Vehicular emissions, air pollution from coal-fired power plants and from factories circle the earth together with vaporised mercury, methane and sulphate aerosols and other airborne toxic chemicals and pesticides.

From a health perspective, deaths from toxins in the air, water and soil outstrips malaria, HIV, TB and Covid19. Indeed it can be said that in many developing countries, particularly those in Southeast Asia, which is known to be the most polluted region in the world with an estimated 3.7 million deaths attributed to outdoor air pollution, few risks have a greater impact on global health than the air we all breathe. Indeed it would not be an exaggeration to state that in many high risk countries the very act of breathing in some of its worst polluted cities could kill its citizens.

Air pollution is an environmental health concern that has no boundaries; what one country emits has a direct impact on countries that are halfway around the world. That is why it is in the interest of safeguarding global health that pollution is addressed at the very source it is emitted wherever it is around the world.

Critical global problem

  • There are four critical aspects that are related to the notion that “pollution knows no borders”.
    Pollution moves globally: Air particulates, heavy metals and some pesticides can move in the air and water, through the food and product chains globally. These toxins cannot be considered local phenomena because the very nature of ecosystems and the global economy spread them far and wide.
  • The young are most vulnerable: Children are most at risk. Low doses of toxicants such as air pollution and lead are known to contribute to a development that medical experts are calling a “silent epidemic” of non-communicable diseases among children such as birth defects, diabetes, leukaemia, autism and more.
  • Air pollution and climate change are inextricably linked: Climate change is intertwined with the air pollution problem. Fossil fuel combustion in power plants, vehicles, factories and homes generate toxic air pollutants and carbon dioxide , the latter the leading cause of global warming. The twin impacts of toxic pollutants and climate change have become the world’s most significant threat to human health. Recent studies show that children of pregnant women who breathe polluted air are at elevated risk of worse birth outcomes, developmental disorders and respiratory diseases.
  • Global pollution problem demands global solution: Air pollution links all of us like an invisible toxic thread. It connects societies that pollute while producing products to consumers in other countries exposed to air, water and soil borne poisons while consuming these products. Solutions are well known and in many cases are cost effective. These solutions such as energy efficiency, cleaner fuels, renewable energy, effluent treatment, enforcement of pollution regulations, etc. have been shown to work successfully and need to be encouraged and brought to scale in low and middle-income countries.

In conclusion, since air pollution has no boundaries and can spread from one region to another it is critical to identify the problem at the source and prevent that pollution from occurring in the first place. This is perhaps the most reasonable and effective strategy for success.

We know that some air pollutants are also climate forcers and climate change drives further air pollution, for example as we are seeing in the case of wildfires or higher ozone levels during heatwaves. One cannot be resolved without addressing the other.

Breaking the vicious spiral

Short-lived climate forcers (SLCFs) can either warm or cool the earth’s climate over short time scales—from days to a few years— when compared to greenhouse gases like carbon dioxide whose warming effect lasts for centuries or more. Examples of SLCFs are methane and sulphate/nitrate/organic aerosols which do not remain in the atmosphere for more than a few days or in the case of methane for a few years.

Because of their short life their effects on the climate differ from region to region and can change rapidly in response to changes in SLCF emissions. SCLFs can have a warming or cooling effect on the climate. Warming SLCFs are either greenhouse gases (e.g. ozone or methane) or black carbon (soot) which warm the climate by absorbing energy. Soot for instance absorbs more than a million times more energy than carbon dioxide. Cooling SLCFs, on the other hand, are made of aerosol particles that cool the climate by reflecting away more incoming sunlight. Emissions have increased since the start of industrialisation and today humans are now the source for several SLCFs such as sulphur dioxide ( which produces sulphate aerosols) and nitrogen oxides ( which produce nitrate aerosols and ozone).

From the above it can be concluded that there is a vicious cycle between SLCFs and climate change impact. With acute warming of the atmosphere the possibility of wildfires increase due to spontaneous combustion of trees and woody biomass that causes formation of black carbon which deposits itself on snow and darkens its surface. This in turn subsequently absorbs more solar energy, leading to more melting and more warming and the vicious spiral continues. Because they possess high radiative efficiencies ( defined as how effective SLCFs are at cooling or warming the climate), SLCFs can have a strong effect on the climate at a regional level even though they have relatively short lifetimes as earlier mentioned. Today, there is a balance between warming and cooling from SLCFs, but according to the opinion of climate scientists, this could change in the future.

Solutions on offer

Improvement in air quality through a variety of measures ranging from improved combustion efficiency, use of less polluting fuels, air pollution regulatory compliance, etc., can result in sharp reductions in emissions and concentrations of SLCFs and result in helping to sever the link between climate impact and SCLFs.

Hitherto policies to limit climate change primarily focused on carbon dioxide but this is now undergoing a change with the important understanding that SLCFs can significantly affect regional temperature changes. Work is underway on how SLCFs work and to quantify their effects. Because reducing some of the SLCF emissions, such as methane or black carbon, can simultaneously improve air quality and reduce warming effects, mitigation of SLCFs is viewed as a favourable “win-win” policy option.

Some countries, particularly the developed countries like US, Canada and Western Europe have done reasonably well in tackling air pollution through mutual agreements between themselves to address trans-boundary air pollution. For instance the reduction of PM2.5 air pollution from 1999 to 2016 in the US and Canada has been dramatic. It would be interesting to briefly review how this was achieved.

In 1991, the U.S and Canada entered into an agreement to address trans-boundary air pollution. The 1991 Air Quality Agreement (AQA) included two annexes. Annex 1 – the Acid Rain Annex focuses on the commitments of both nations to reduce emissions of sulphur dioxide and nitrogen oxides, the primary precursors of acid rain. Under Annex 2, the Scientific and Technical Activities and Economic Research Annex, the two nations agree to coordinate their respective air pollution monitoring networks and exchange information. In 2000, a third annex was added to the AQA, namely the Ozone Annex. This annex commits the two nations to reducing nitrogen oxides (NOx) and volatile organic compounds (VOCs) the precursor pollutants to ground-level ozone which is the major component of smog.

The AQA established a formal and flexible method of addressing trans-boundary air pollution and paved the way for cooperation on a variety of air quality issues including acid rain, ozone and particulate matter. Ever since the Air Quality Agreement between the US and Canada there has been a dramatic reduction in air pollutants in both countries as a result of an integrated collaborative effort.

  • Some of the highlights of the progress made under the AQA are:
    Both the US and Canada have been successful in reducing SO2 and NOx emissions and thus, mitigating the impact of acid rain on each side of the border. In 2006 Canada’s total SO2 emissions were 2 million tonnes or about 38 percent below the national cap of 3.2 million tonnes. This represented a 35 percent decrease from the 1991 emission level – the year when the AQA agreement between the two nations came into effect.
  • The USA succeeded in meeting its commitment to reduce annual SO2 emissions by 10 million tons from 1980 levels by 2000. National SO2 emissions from all sources have fallen from nearly 26 million tons in 1980 to less than 13 million tons in 2007 ( www.epa.gov/ttn/chief/trends>). Most of the reduction in SO2 emissions are due to the Acid Rain Program.
  • In the case of NOx, Canada surpassed its reduction target at power plants, major combustion sources, and metal smelting operations by 100,000 tonnes below the forecasted levels of 970,000 tonnes between 1990 and 2007. Similar figures for the US was 3.3 million tons in 2007 compared to a level of 6.7 million tons in 1990 when the acid rain program was initiated.
  • Under the Ozone Annex, the US and Canada are required to report on the amount of Ozone, NOx and VOCs in the air we breathe (i.e., ambient concentrations) from all relevant monitors within 500 km of the border. Both countries have extensive networks to monitor ground-level ozone and its precursors, and both countries prepare routine reports summarising measurement levels and trends.

(Canadian Source: www.etc-cte.ec.gc.ca/naps/index_e.html; US Source: www.epa.gov/air/data/index.html)

The views expressed in this article are of the author and do not necessarily reflect the views of the organisation