How Can Cleaner Air Lead to a Cleaner, Healthier, and Safer Planet?

According to the World Health Organisation (WHO), nearly 9 out of 10 people are exposed to air pollution levels that put them at an increased risk for diseases including heart disease, stroke, chronic obstructive pulmonary disease (COPD), cancer and pneumonia. However, cleaner air is not just about outdoor air quality; it is also important to recognise that household air pollution caused by the use of solid fuels for cooking accounts for an estimated 3.8million premature deaths each year.

This year on Clean Air Day it is great to see a focus on protecting children’s health from air pollution and we are grateful for the research of Global Action Plan and EarthSense to show how much work still needs to be done when we see that 27% of UK schools are located in areas above WHO air pollution limits.

Many of the drivers of air pollution (for example, the combustion of fossil fuels) are also sources of CO₂ emissions and short-lived climate pollutants, such as ozone, methane and black carbon that greatly contribute to climate change and affect human health.  Most policies to provide cleaner air or reduce air pollution offer a “win-win” strategy for both health and climate. Lower levels of air pollution result in better cardiovascular and respiratory health of populations in both the long- and short-term. Reducing ambient and household air pollution can also contribute to the near- and long-term mitigation of climate change.

Many of the sources of outdoor air pollution are also sources of high CO₂ emissions. For example, the use of fossil fuels for power generation, industry and polluting transport are all major sources of both particulate matter and CO₂. However, although short-lived climate pollutants (SLCPs) persist in the atmosphere for short lifetimes, their global warming potential is often much greater than carbon dioxide (CO₂).  For example, black carbon, a component of fine particulate matter (PM), is one of the largest contributors to global warming after CO₂. Black carbon warms the earth’s atmosphere by absorbing sunlight, thereby accelerating the melting of snow and ice.  Methane, another SLCP, is a potent greenhouse gas that is 84 times more powerful than CO₂ and is a precursor to the air pollutant ozone. Ozone and black carbon affect weather processes and decrease agricultural yields, thus threatening food security.

Air pollution is the presence of one or more contaminants in the atmosphere, such as dust, fumes, gas, mist, odour, smoke or vapor, in quantities and duration that can be injurious to human health as well as to our planet. The main pathway of exposure from air pollution is through the respiratory tract. Breathing in these pollutants leads to inflammation, oxidative stress, immunosuppression, and mutagenicity in cells throughout our body, impacting the lungs, heart, brain among other organs and ultimately leading to disease.  Air pollution is a risk for all-cause mortality as well as specific diseases. The specific disease outcomes most strongly linked with exposure to air pollution include stroke, ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, pneumonia, and cataract (household air pollution only).  There is suggestive evidence also linking air pollution exposure with increased risk for adverse pregnancy outcomes (for example, low-birth weight, small for gestational age), other cancers, diabetes, cognitive impairment, and neurological diseases.

Although there are many toxins that have adverse impacts on health, pollutants with the strongest evidence for public health concern include particulate matter (PM), carbon monoxide (CO), ozone (O₃), nitrogen dioxide (NO₂) and sulphur dioxide (SO₂). Fine particulate matter is an especially important source of health risks, as these very small particles can penetrate deep into the lungs, enter the bloodstream, and travel to organs causing systemic damages to tissues and cells. The health impacts from exposure to ambient air pollution or household air pollution are dependent on the types and concentrations of the pollutants in the air pollution mixture to which an individual is exposed. However, the health risks and disease pathways between ambient and household air pollution exposure are often similar, due to their similar composition. Fine particulate matter for example is a common and critical pollutant of both ambient and household air pollution leading to negative health impacts.

Unfortunately, much like climate change at large and the current SARS-COV-2 pandemic, air pollution does not affect everyone equally. The level of health risk varies between populations. People living in low and middle-income countries are typically more vulnerable to air pollution due to the higher levels of air pollution they are exposed to each day, and the higher prevalence of diseases that are negatively affected by air pollution exposure, like asthma. Populations living in slums or near busy highways or roads, lacking access to clean cooking equipment, or in certain occupations are other examples of populations more vulnerable to the adverse impacts of air pollution. The health risks of household air pollution are strongly correlated with poverty (or sometimes referred to as energy or fuel poverty). These risks are not distributed evenly across countries, or even within countries.

People in sub-Saharan Africa, South-East Asia, and the Western Pacific experience the highest rates of health problems from exposure to indoor pollutants related to household energy use. Within these regions, the burden of disease falls most heavily on rural households. Because they lack the resources to obtain cleaner fuels and devices, people in lower-income households rely mostly on fuels that they can freely gather, such as wood and dung and more traditional inefficient cooking stoves.  Within poorer households, women, children, and the elderly bear the brunt of health and other impacts of household air pollution.

In most low- and middle-countries, women and children perform the domestic tasks related to household energy provision including gathering and processing fuel, tending the hearth, and cooking meals; all of which led to chronic strain and injury. As they spend the most time in the kitchen or in polluted living spaces, women and children have higher rates of exposure to particulate matter and other pollutants emitted by stoves and open fires. Additionally, reliance on inefficient household fuels and devices limits the time available, especially to women, for income generation, schooling, and other opportunities for economic development. Similarly, households with limited or no access to a clean and reliable source of lighting can lose opportunities for educational and income-generating activities outside of daylight hours. Energy poverty thus locks people in a vicious cycle, sapping them of time, damaging their health, and limiting their access to better livelihoods, education, and other paths out of poverty.

To understand the impact of the problem of air pollution we first have to be able to monitor, model and forecast before we start considering mitigation plans for citizens, corporations, and governments. A new generation of monitoring and modelling tools is now available to assess and forecast air pollution trends, and to help in designing the most effective strategies to improve air quality. These monitoring tools (in-situ networks, Earth observations, low-cost sensors, emission inventories, and air pollution models) enable better analyses of air quality and its driving factors in various parts of the world. The rapid development of new technologies is lowering the cost and advancing the field of air quality monitoring. Stationary and dynamic networks of low-cost sensors (LCS) for air pollution monitoring are being established. Sensors for air pollution monitoring are being deployed on mobile phones, drones and retrofitted cars that serve as mobile monitoring stations. New, lower-cost sensors are becoming more widely available as commercial products, presenting new opportunities for innovative applications and broader participation in air quality monitoring and management by communities, citizens, and companies.

This should lead to more dense monitoring networks that complement regulatory monitoring, and to better identification of pollution hot spots and specific sources. In recent years, advances in satellite data retrieval and analysis have also contributed to important progress in air quality assessment. Information gathered by satellites is essential to generating estimates of air pollution exposures around the world. Ground monitoring of fine particulate air pollution is supplemented with information from remote-sensing satellites and other sources to produce high-resolution estimates of concentrations for every country. These estimates form the basis of the calculations of country-level, regional and global, burden of disease.

It is encouraging to see the WHO is leading a Global Platform on Air Quality and Health in partnership with international and national organizations, to address the rising health toll of air pollution. The Global Platform brings together international and national experts, scientists, and policy actors to strengthen ways to track and report progress on air pollution. A key element of the platform’s work is developing a data clearinghouse to help countries and cities reduce exposure to air pollution, its associated burden of disease and more effectively tackle the sources of health-damaging air pollution. One of the Global Platform’s current areas of focus is improving methods to integrate air pollution data from satellite, ground monitoring and chemical models, and to better characterize air pollution sources (such as transport, industry, and agriculture). But it is also encouraging that products like MappAir are being developed by companies like @EarthSenseAQ are also being used to integrate data and products from the Copernicus Atmosphere Monitoring Service (CAMS) and Sentinel-5P and will also welcome data from future sources too such as NASA’s Multi-Angle Imager for Aerosols (MAIA) mission scheduled for launch in 2022.

The Secretary General of the UN recently highlighted a number of key steps for climate action such as: putting a price on carbon, ending fossil fuel subsidies, shifting the tax burden from taxpayers to polluters, phasing out coal and investing in renewable energy and green infrastructure. These are all essential global policies that we need to unite around but it is also worthwhile considering what we can do as citizens: switch to more fuel-efficient vehicles or ideally zero emissions but if lower-emission transport options are not accessible. One of the biggest changes we can all make is to find ways to include active travel as part of your day. As part of decommissioning of pollutant practices and plants, instead of removing these sites entirely some could be repurposed as solar plants and or museums to educate the next generation as to why we must move forward and not go back to these fossil fuels.

Greater investment and collaboration are needed to characterise air pollution sources and to understand the linkages between human, animal, plant, and the planet’s health as a consequence of exposure to air pollution. Understanding is the first step, but action must be taken to address the sources and provide mechanisms to support individuals in all countries reduce their exposure to poor air quality, whether through subsidies of energy efficient vehicles or subsidies for renewable home energy or increased tax burden on polluters that would naturally trickle down to citizens making these products and services less attractive to the consumers.