Air Pollution, Climate, and Health: An Integrated Perspective on Their Interactions

Air Pollution, Climate and Health integrates the current understanding of the issues of air pollution, climate change and human health. The book provides a comprehensive overview of these issues to help readers gain a better understanding of how they interact and impact air quality and public health. Regional examples from across the globe include issues related to PM 2.5, haze, winter pollution, heat related mortality and aerosols. These issues are addressed utilizing current research and laboratory-based, observation-based, and modeling-based analysis. This is an essential resource for all professionals investigating the impacts of climate change or air pollution on human health.

• Provides a comprehensive understanding of the interactions between climate change, air quality and human health
• Includes evidence-based findings to help clarify the mechanisms on how air pollution impacts climate and how a changing climate is impacting those pollutants
• Covers a number of pollution sources and products impacting climate change, including energy, haze, particulate matter, aerosols, PM 2.5 and transport

• Language: English
• Publisher: Elsevier Science
• Release date: Apr 14, 2021
• ISBN: 9780128203958

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States

Part 1

General perspective

Chapter 1: Overview of climate change, air pollution, and human health

Xiang Xiao; Meng Gao    Department of Geography, Hong Kong Baptist University, Hong Kong SAR, China

Abstract

Climate change and air pollution are the two biggest challenges in the twenty-first century. The health impacts of air pollution have long been recognized, followed by the emerging climate change topic, which have aroused massive debate among both scientists and common residents. Accumulating evidence has shown that climate change and air pollution pose multiple health threats to human through complex and interacting pathways. This chapter briefly summarizes the documented health effects of climate change and air pollution, and the underlying linkage and interaction, as well as some issues that need to be addressed in future research and policy-making practice.

Keywords

Air pollution; Climate change; Health

1: Introduction

As early as the year of 1979, by the First World Climate Conference (FWCC), alerts were initially brought to international attention about long-term global climate change caused by anthropogenic activities. With the development of atmosphere modeling and improved monitoring and detection techniques, the evidence of global warming, on the one hand, grew in scientific communities, and on the other hand, the concept of greenhouse effect had reached every villager of the Earth village. The effects of climate change are more pronounced today, with increased frequency of extreme weather events, heat stress, floods, drought, as well as other indirect health consequences, for example, food shortage, under-nutrition, and increased vector-mediated diseases. In fact, from the birth of the earth, the climate system has been going through a constant natural variability which was associated with changes in the earth’s orbit and the onset and recession of the great ice ages. However, the ongoing trend of global warming, which was mainly due to anthropogenic emission of greenhouse gases (CO2, CH4, N2O, HO2, etc.), has shown and will continue to pose even more catastrophic risk to human health. Not only economic activities, but also human health and wellbeing are vulnerable to climate change, with no region being immune from the negative consequences (Smith et al., 2014).

Greenhouse gases emissions have been rising steadily since the industrial revolution (Petroleum, 2014). The main source of greenhouse gas (GHG) emissions is burning of fossil fuel (Watts et al., 2015). At the same time, notable combustion byproducts are the particulate matter with high specific surface area, which trigger a series of physical and biochemical reactions to form the well-known particle pollutants. As the climate-modifying pollutants (for instance, black carbon or carbon dioxide) and air pollutants (e.g., PM2.5) share similar sources, air pollution is used as a marker of sustainable development. In addition, studies show that meteorological factors, (i.e., temperature, humidity, and wind speed and direction), play essential roles in determining patterns of air pollutants over multiple scales in time and space (Kinney, 2008).

There was debate about whether human-induced climate change was real, and whether recently observed global warming could be causally attributed to human activity. With evidence accumulating and technology of meteorology advancing, this debate is largely over. Earth's surface temperature in the last 30 years has increased more than in the last decade since 1850 (IPCC, 2014). It is projected that between 2030 and 2050, approximately additional 250,000 lives will be lost each year due to malnutrition, malaria, diarrhea, and heat stress alone because of climate change (WHO). The direct costs to health impacts are estimated to be between USD 2 and 4 billion per year by 2030. The health impacts of air pollution had long been recognized and ambient air pollution in both urban, suburban and rural areas was estimated to cause approximately four million premature global deaths per year in 2016, according to WHO. Nowadays, we cannot be more confident that we are now faced with the unprecedented challenge and opportunity in the twenty-first century.

This chapter will briefly introduce what impact the climate change and air pollution could pose to public health, outline the benefits of tackling these problems, and discuss possible difficulties and needs in future scientific research and policy-making practice.

2: Dramatically growing evidence

The number of literatures concerning the health-related aspects of climate change and air pollution impacts has grown significantly over the past four decades (Fig. 1). The number of publications on air pollution and health is far more (over ten-fold) than its climate change and health counterpart before the year of 2007. The research history of air pollution and health is reasonably longer than that of climate change, while just in recent years, some new insights started to reveal the complex and interacting ways in which both climate change and air pollution affect public health. This brief chronicle neither differentiates across the various subcategories of the climate change and air pollution literature, nor claims to be comprehensive in terms of literature produced in languages other than English.

Fig. 1

Fig. 1 Number of climate change and air pollution publications listed in the PubMed database for the years 1979–2019.

3: Health effects of climate change and air pollution

Climate change poses direct risks to human health (e.g., extreme weather events such as storms and wildfires), indirect impacts on ecosystems (e.g., loss of agriculture and tendency to disease), and impacts on economic and social structures (e.g., migration and conflict). The multiple and interacting pathways form a complex network (Fig. 2). Studies have demonstrated some physiological effects caused by climate change, for example, due to exposure to heat, and increasing incidences of noncommunicable diseases, for example, respiratory and cardiovascular disease and health loses due to extreme weather events. Indirect health effects include food insecurity, the spread of water- and vector-borne infectious diseases, limited access to health services and even population displacement.

Fig. 2

Fig. 2 An overview of the links between greenhouse gas emissions, climate change, and health. The causal links are explained in greater detail in the section about climate change and exposure to health risks ( Watts et al., 2015).

3.1: Increased temperature

Overall, human activities are estimated to have caused 1.0°C on average (range: 0.8°C to 1.2°C) of global warming above pre-industrial levels (Masson-Delmotte et al., 2018), which means heatwaves and prevailing warmth for annual conditions are likely to become more frequent and annual cold days are shortening. There is well-established association between hot days and increased mortality (Åström et al., 2013), and evidence is also accumulating that heat-related death is likely to be related to climate change (Smith et al., 2014). Taking the 2003 heatwave in Europe as an example, Stott et al. (2004) estimated that it was very likely (confidence level >   90%) that human influence has at least doubled the risk of heatwave events in 2003. Increased minimum temperatures may have contributed to a decrease in deaths associated with cold spells; however, studies have shown that the health effects of more frequent extreme heat far outweigh the benefits of fewer cold days (Kinney et al., 2015; Martinez et al., 2018).

3.2: Frequent droughts, floods, and storms

Floods and droughts are projected to increase (Patz et al., 2005). Together with storms, these natural disasters threatened health through drowning, injuries, hypothermia, and infectious diseases, and harm food crops, thus causing multiple social and economic losses. Mortality rates and increased risks of disease such as hepatitis E, gastrointestinal, and diarrheal diseases, leptospirosis, as well as higher level of psychological stress, were associated with floods (Alderman et al., 2012; Levy et al., 2016).

3.3: Malnutrition and infectious diseases rising

Malnutrition and infectious diseases are the secondary health threats derived from climate change-induced disasters. Extreme weather events have profound effects on the living condition (e.g., temperature, precipitation, and humidity) of infectious disease vectors (such as mosquitoes, ticks, and sandflies). For example, reproduction and survival rates of mosquitos are thus strongly affected by variability in temperature and humidity (Gubler et al., 2001), particularly the density of water-bearing containers. Malaria transmission has also been reported to be associated with maximum temperature (Laneri et al., 2019). Dengue fever, another serious vector-borne infectious disease, could be reduced by mitigation of greenhouse gas emissions in a model projection (Li et al., 2017).

Temperature has also been found associated with food- and water-borne infections. For example, an estimated 30% of reported cases of salmonellosis across much of continental Europe could attribute to higher-than-average temperatures. Changing weather patterns are another important factor which may affect the incidence of water-borne diseases, for example, the contamination of drinking water, or providing the conditions needed for bacterial growth (Lipp et al., 2002).

3.4: Air quality

Almost all nonclimatic pollutants (such as ozone) are harmful to health, either directly or by contributing secondary pollutants to the atmosphere. Heat waves and drought pose higher risk of wildfires breakout, which releases particulate matter, ozone, and other toxic substances that may affect large group of people for a considerable long period of time. Reid et al. (2019) found that PM2.5 levels during an intense wildfire in California in 2008 reached levels up to more than six times the NAAQS of 35 μg/m³, and ozone occasionally exceeded the NAAQS of 70 ppb.

The independent and combine effects of these climate-altering pollutants can cause a wide range of health issues, including respiratory, cardiovascular problems, and issues of mental health and psychosocial well-being. It is projected that climate change will continue to affect air quality, including ozone and fine particles (PM2.5). More serious health consequences in the absence of emission control are expected. Asthma, for instance, is one of the diseases associated with air pollutants exposure. Nassikas et al. (2020) anticipated an annual average of more than 3000 averted ozone-related asthma emergency department visits during the 2045–2055 period, which translates to USD $1.7 million costs annually. Increases in ambient ozone concentrations under high global warming and emissions scenarios are projected to result in 1476 (95% eCI: 898-2977) nonaccidental deaths per year in 2053–2055 compared to 2013–2015 (Chen et al., 2018b).

Air pollution, a long-recognized health risk factor, poses detrimental influence on human in more direct ways. Respiratory system, due to direct contact with pollutants, is a well-established effect target of air pollution, which not only affects lung function growth in children (Gauderman et al., 2004) but also leads to inflammation in airways and possibly contributes to lung aging, such as chronic obstructive pulmonary disease (COPD) (Berend, 2016). In addition, air pollution also accounts for 19% of all cardiovascular deaths and 21% of all stroke deaths (Hadley et al., 2018). The effects on cardiovascular diseases of long-term exposure to air pollution are well documented (Newby et al., 2015), and studies showed that even a relatively low PM levels could contribute to decreased life expectancy (Pope III et al., 2004). Immune system has also been found involved. Air pollution plays a role in both the development and the exacerbation of allergic diseases, such as allergic rhinitis (Deng et al., 2016) and even autoimmune diseases (Bernatsky et al., 2016). Nevertheless, there is accumulating evidence on cognitive function and neurologic diseases (Chen et al., 2017; Fordyce et al., 2018), diabetes (Eze et al., 2015), obesity, and endocrine changes (Calderón-Garcidueñas et al., 2015).

According to WHO, over 90% of the global population live in places where air pollution levels exceed WHO guideline limits. And many studies have found that air pollution, even below the safe levels considered by those standards, could be harmful to health. The good news, however, is that this is more of a regional problem and the solutions will have almost immediate benefits compared to climate change, which will affect nature, economic activity and the health and well-being of people around the world.

4: Linkage and interaction between climate change and air pollution

The sources of climate change and air pollution are broadly the same: polluting energy systems (Fig. 3). The sectors that produce most GHGs—energy, transport, industry, agriculture—are also the main sources of PM2.5 and other important air pollutants (black carbon, methane, ozone, etc.).

Fig. 3

Fig. 3 Main sources of greenhouse gas emissions and urban ambient air pollution ( World Health Organization, 2018).

In addition to the main causes of anthropogenic activities, the mechanism basics of climate change and air pollution are also closely linked. For instance, recent studies have found that weather and meteorology patterns have strong influences on the spatial and temporal distribution of air pollution concentrations through multiple pathways that alter the extent to which air pollutants are emitted and transported, are chemically transformed, are dispersed and diluted, and are eventually deposited (Fiore et al., 2015; Kinney, 2008).

Climate change may affect air quality in the future, including levels of photochemical oxidants (e.g., ozone) and fine particulate matter (e.g., PM2.5). In contrast to their anthropogenic counterparts, there are also naturally occurring air pollutants, such as pollen, VOCs from trees, smoke from wildfires, and windblown dust, which are closely linked with and driven by climate change (Kinney, 2018).

Now that climate change and air pollution problems share similar main causes and sources, and they may enhance the effect of each other, thus causing much higher synergy effect, taking measures to mitigate climate change or air pollution could bring enormous co-benefits for human health.

5: Co-benefits of tackling climate change and air pollution

Co-benefits are defined as additional benefits related to the reduction of greenhouse gas emissions that are not directly related to climate change, such as air quality improvement, technological innovation, or employment creation (Markandya et al., 2018). Emission control could, on the one hand, reduce air pollution and respiratory incidence, on the other hand, safer active transportation reduces traffic crashes and lowers the incidence of obesity, diabetes, coronary heart disease, and stroke. Additional health benefits often result from a variety of causal factors across social and environmental determinants of health. For example, renewable energy, clean fuel for cookstoves will not only mitigate climate change, (e.g., reduce black carbon, carbon monoxide), but also protect residents from household air pollution, especially the vulnerable subpopulation groups, including the poor, women, children, and the disabled. Mitigation measures can help to reduce existing health inequities. Other co-benefits include injury prevention or enabling physical activity with the development of sustainable cities with fewer fossil-fuel driven vehicles.

6: Future research and policy needs

6.1: Exposure assessment

PM2.5 measurements can be directly related to health risk assessment and are therefore of particular interest. Reliable estimates of exposure to air pollutants are critical to better inform policy makers. These data are needed to track progress in improving air quality and to evaluate the effectiveness of policies to reduce air pollution, as well as the extent to which they contribute to health protection. Monitoring air quality is the first but crucial step in assessing health risks and developing policy. Ground-based monitoring stations are the main source of air quality data, and the number of ground-based measurements available in high-income countries has doubled. However, a major limitation is the huge gaps in monitoring and reporting between high-income and low- and middle-income countries, as well as the availability of data. Another limitation of these data is that air pollutant concentrations may be too high to provide accurate estimates of exposure risk in relatively small study areas. To address these limitations, researchers and scientists have been devoted to developing comprehensive and reliable models to predict the exposure to PM or other air pollutants (Chen et al., 2018a; Wang et al., 2015).

6.2: Nonlinearities and interactions between effect

The magnitude and nature of health impacts are hard to predict with precision; and the statistical models used to yield results could be limited to the study’s specific context, for example, the range of exposure levels is, in most cases, varied dramatically in different study regions. Health consequences and exposure in global scale are relatively scarce. In addition, nonlinear relationship of exposure and response is likely to exist and, however, be ignored in some of our analysis. Furthermore, single risks can interact with one another to produce unexpected higher or lower effect, such as the aforementioned air pollution and climate/weather condition interaction and vulnerable population due to health inequities. Future research should continue to focus on possible underlying interaction and work with other related sectors to gain more all-rounded conclusions.

6.3: For policy makers

Raise awareness: Public awareness of the health losses associated with air pollution may be a powerful catalyst for collective ambition to mitigate climate change. Better cooperation: Both domestical and international coordination among the health, energy, transport, agriculture, urban planning and other sectors will be necessary to set priorities that ensure maximum benefits for both health and climate regionally and globally. All-rounded perspective: perspective from public health has the potential to unite all actors involved to work for a common aim—the health and well-being of our families, communities, and countries.

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