from the ineffective combustion of fossil and solid fuels have been well‐documented and yet remain as unprecedented environmental health risks. As early as 2005, the WHO issued air quality guideline limits on PM pollutants that measured 2.5 μm or less – PM2.5‐ and 10 μm or less – PM10,‐ based ‘on the close, quantitative relationship between exposure to high concentrations of small particulates (PM10 and PM2.5) and increased mortality or morbidity, both daily and over time’ (WHO (2005)) Box 1.1 specifies the WHO guidelines. In doing so, WHO made clear that: ‘Small particulate pollution has health impacts even at very low concentrations – indeed no threshold has been identified below which no damage to health is observed. Therefore, the WHO 2005 guideline limits aimed to achieve the lowest concentrations of PM possible’ (emphasis added, WHO 2005).
Box 1.1 WHO air quality guideline values issued in 2005.
| Particulate matter (PM): WHO air quality guideline values* Fine particulate matter (PM2.5) 10 μg/m3 annual mean25 μg/m3 24‐hour meanCoarse particulate matter (PM10)20 μg/m3 annual mean50 μg/m3 24‐hour mean |
* According to the WHO, PM pollutants such as nitrates and black carbon penetrate deep into the lungs and into the cardiovascular system, posing the greatest risks to human health. PM2.5 was identified as one of the principal air pollutants directly linked with causing strokes, ischaemic heart disease; chronic obstructive pulmonary disease and lung cancer.
Source: WHO (2005) Air Quality Guidelines.
A decade later, in 2015, in response to air pollution being identified as a major global public health threat, the 194 WHO member states adopted the first World Health Assembly resolution to ‘address the adverse health effects of air pollution’. Member states agreed on a Road Map aimed at providing an enhanced global response to the adverse health effects of air pollution. Amongst the main elements of this road map were the monitoring and reporting of air pollution and enhanced systems, structures and processes for monitoring and reporting health trends associated with air pollution (WHO 2015). The WHO’s Secretariat resolution was grounded in a report which was stark and succinct as to the extensive and yet inequitable morbidity burden of air pollution:
‘Air pollution is one of the main avoidable causes of disease and death globally. About 4.3 million deaths each year, most in developing countries, are associated with exposure to household (indoor) air pollution. A further 3.7 million deaths a year are attributed to ambient (outdoor) air pollution.
Even at relatively low levels air pollution poses risks to health, and because of the large number of people exposed it causes significant morbidity and mortality in all countries. However, although all populations are affected by air pollution, the distribution and burden of consequent ill‐health are inequitable. The poor and disempowered, including slum dwellers and those living near busy roads or industrial sites, are often exposed to high levels of ambient air pollution, levels that appear to be worsening in many cities. Women and children in households that have to use polluting fuels and technologies for basic cooking, heating and lighting bear the brunt of exposure to indoor air pollution.
Most air pollutants are emitted as by‐products of human activity, including heat and electricity production, energy‐inefficient transport systems and poor urban development, industry, and burning waste and brush or forests’ (emphasis added, WHO 2015, pp. 1–2).
Figure 1.5 excerpted from the WHO’s 2018 special report on climate and health provides global contributions of different sectors to the GHG emissions and shows that the sources of climate change and air pollution are broadly the same. It outlines why measures to curb the grave public health impacts of urban PM ambient pollution matter for millions of lives.
PM air pollution has been identified as a risk factor for many of the leading causes of death including heart disease, stroke, lower respiratory illnesses, lung cancer, diabetes and COPD (WHO 2016a; Cohen et al. 2017). WHO’s 2018 report included a critical finding as to why addressing air pollution matters so much for the lives of so many across the globe: ‘The most direct link between climate change and ill health is air pollution’ (p. 16). A significant finding by the WHO was that if climate change is not mitigated, global income inequality could increase grossly especially since the health impacts of climate change are unevenly distributed (WHO 2018, p. 25). But more recently, a cross‐national collaborative study spanning the world’s leading medical research and scientific institutions has found that exposure to ambient PM pollution is ‘several fold larger’ than previously estimated, ‘suggesting that outdoor particulate air pollution is an even more important population health risk factor’. The study based on data from 41 cohort studies of outdoor air pollution from 16 countries – the Global Exposure Mortality Model (GEMM) estimated 8.9 million deaths in 2015, a figure 120% larger than the risk function used in the more established Global Burden of Disease (GBD) metrics. The researchers conclude that: ‘The results suggest that PM2.5 exposure may be related to additional causes of death than the five considered by the GBD and that incorporation of risk information from other, non‐outdoor, particle sources leads to underestimation of disease burden, especially at higher concentrations’ (Burnett et al. 2018, abstract).
Figure 1.5 Main sources of GHG emissions and urban ambient air pollution.
Source: WHO (2018, p. 17).
The disconcerting human development reality is that the layering of climatic adversities, poverty, and marginalization, combined with the health impacts of exposure to air pollution, and the lack of access to non‐polluting energy sources puts millions of lives at stake. There is irrefutable evidence that climate change cannot be ameliorated without massive reductions of CO2 and other GHGs. But, a central argument advanced is that the global community as a whole has not done enough to address the linkages between climate change and air pollution and, in particular, that global policy silos on clean energy access and climate change have relegated the curbing on SLCPs associated with toxic levels of PM pollution to the margins. As evidenced by their name, and unlike CO2 emissions which are longer lived in the atmosphere, SLCPs are pollutants that persist for a short duration/time span in the atmosphere. But, SLCPs have been found to be extremely potent in terms of their global warming potential compared to longer lasting GHGs such as CO2. Reducing SLCPs like black carbon (BC), methane (CH4 – which is also a recognized GHG) and tropospheric ozone (O3) offers multiple benefits – short‐term climate mitigation and public health.
A 2011 scientific assessment released by UNEP and the World Meteorological Organization (WMO) found that measures targeting SLCPs could achieve ‘win–win’ results for the climate, air quality and human well‐being over a relatively short timeframe (UNEP/WMO 2011). This 2011 joint report entitled ‘Integrated Assessment of Black Carbon and Tropospheric Ozone’ found that reducing SCLPs ‘now will slow the rate of climate change within the first half of the century’ and that a small number of focused emission reduction strategies targeting BC and O3 could immediately ‘slow the rate of climate change within the first half of the century’ (UNEP/WMO 2011, p. 1). BC is a major component of soot and exists as particles in the atmosphere. Emissions that result from the incomplete/inefficient combustion of solid fuels and traditional biomass are released as a mixture of health‐damaging indoor
