14.1 Understanding Environmental Health

Nightingale’s Environmental Theory

Florence Nightingale was an early advocate for public health and hygiene, her environmental strategy aimed to improve living conditions and prevent the spread of diseases. Nightingale’s Environmental Theory viewed nursing as the process of using the client’s environment to assist them in their recovery (Gilbert, 2020). Observing that many wounded soldiers were dying from preventable diseases during the Crimean War (1853–1856), Nightingale realized that the unsanitary conditions in military hospitals contributed to the high mortality rate. To address this issue, she developed an environmental strategy that focused on fresh air, clean water, sanitation, hygiene, and light (Gilbert, 2020).

Although less well known as a statistician today, Nightingale was the first woman inducted into the renowned Royal Statistical Society. During the Crimean War, she painstakingly collected and analyzed data on the causes of death and mortality rates of soldiers. To effectively communicate her findings, Nightingale developed innovative visualization methods, including the coxcomb, a graphic representation similar to a pie chart, to demonstrate that a substantial proportion of soldier deaths were due to disease, exposure, and infection rather than injuries from battle and were therefore preventable (Figure 14.2).

Figure 14.2 Florence Nightingale created infographics like this coxcomb to easily communicate complex data. (credit: “Diagram of the causes of mortality in the Army in the East” by National Library of Medicine, Public Domain)

One Health

The One Health approach (CDC, 2022f) emphasizes the interconnectedness of human health, animal health, and the environment. With growing populations and expanded habitats, closer contact between humans and animals increases disease transmission, while environmental changes and global movements amplify disease spread. These shifts have led to the rise of both known and emerging zoonotic diseases, impacting millions of humans and animals each year. Common One Health issues include emerging zoonotic diseases, antimicrobial resistance, vector-borne diseases, food safety, environmental contamination, and the impacts of climate change. For example, vector-borne diseases such as Lyme, transmitted from ticks to humans, now occur in a wider area as ticks adapt to environmental change. As a result, populations that were previously not at risk of Lyme disease now face increased likelihood of exposure. The CDC uses One Health to monitor and manage public health threats and plan effective public health interventions in collaboration with partners. Ultimately, One Health aims to prevent zoonotic outbreaks, enhance food and water safety and security, mitigate antimicrobial resistance, safeguard global health, and promote biodiversity and conservation. Learn more about One Health in action here.

Upstream vs. Downstream

As introduced in What Is Population Health?, upstream and downstream approaches to health and health care represent different points in the chain of events leading to particular positive or negative health outcomes. Upstream approaches focus on the beginning of the causal pathway by addressing underlying factors, such as the social, economic, and environmental determinants that contribute to health outcomes. Upstream factors are often difficult to see or measure, but they can have a profound impact on human health. For example, programs to reduce poverty or promote sustainable agriculture, campaigns to raise awareness or educate the public on a particular topic, and environmental regulations to reduce pollution are upstream interventions aimed at improving overall health outcomes.

Conversely, downstream factors occur later in the chain of events. These factors are more specific and often relate to individual behaviors and health care delivery systems. Downstream factors are more visible and easier to measure, but they are often the result of upstream factors. Examples of downstream factors in environmental health include individual lifestyle choices and access to medical and preventive care. Interventions using a downstream approach focus on mitigating the immediate effects of health problems, such as screenings, medications, procedures, and individual behavior change programs. While downstream interventions are necessary for treating existing health problems, they often fail to address their root causes and may not lead to long-term improvements in population health. For example, one upstream factor that contributes to air pollution is the burning of fossil fuels, which releases harmful pollutants into the air that cause respiratory problems, heart disease, and cancer. A recent study found that nitrogen oxide, particulate matter, and ozone from U.S. oil and gas production alone resulted in 7,500 additional deaths, 410,000 incidents of asthma attacks, and 2,200 fresh cases of childhood asthma throughout the United States in the year 2016 (Buonocore et al., 2023). An upstream approach would be to control air pollution and reduce exposure. On the other hand, downstream consequences of air pollution include asthma attacks, heart attacks, and premature deaths. Downstream interventions would focus on mitigating the impact of the air pollution by providing treatment for respiratory issues or distributing masks for outdoor use during times when air quality is poor. Addressing upstream factors helps to prevent environmental problems from occurring; addressing downstream factors mitigates the impact of environmental problems.

Environmental Justice

Environmental justice refers to the fair and equitable treatment and meaningful engagement of every individual, irrespective of race, color, national origin, or socioeconomic status, in the development, execution, and enforcement of environmental laws and policies (U.S. Department of Energy, 2023). The goals of environmental justice are to offer equal protection from hazards and to ensure equal involvement of communities in making decisions about policies and regulations that impact them. Advocates of environmental justice aim to ameliorate the disproportionate burden of environmental hazards encountered by certain marginalized and vulnerable populations (Environmental Protection Agency [EPA], 2023j). Environmental justice connects environmental issues with broader social justice concerns, recognizing that environmental degradation often intersects with issues related to health inequities, housing, education, and economic opportunity. As such, advocates seek to foster sustainable and inclusive communities that prioritize the well-being and health of all residents. They work to raise awareness about these issues, mobilize affected communities, and promote policies and practices that prioritize environmental equity and fairness.

The concept of environmental justice emerged in the 1970s in response to environmental issues often faced by low-income communities, BIPOC communities, and other marginalized groups (Lynch et al., 2021). These communities carry a greater burden, with increased exposure to pollution, toxic substances, hazardous waste, and other environmental hazards due to structural factors such as discriminatory land-use policies, socioeconomic disparities, and lack of political power. Examples of environmental justice issues include siting of polluting industries in low-income neighborhoods, lack of access to clean and safe drinking water in certain communities, and unequal enforcement of environmental regulations. For more on these issues, see Structural Racism and Systemic Inequities.

The movement gained momentum in the 1990s, with the term officially recognized in the Presidential Executive Order 12898 in 1994, directing federal agencies to address environmental justice issues in their programs and policies (EPA, 2023a). In 2021, President Biden issued an executive order to initiate Justice40, an environmental justice initiative aiming to address environmental and climate issues while prioritizing equity and justice for disadvantaged communities. The initiative, based on the principle that communities that have been disproportionately harmed by pollution and climate change should be first in line to benefit from the transition to a clean energy economy, commits to investing 40 percent of the overall benefits from federal climate and clean energy programs into these communities (EPA, 2023m). Justice40 represents a significant step toward integrating environmental justice principles into federal climate and environmental policies, with a focus on rectifying historical and systemic disparities in environmental protection and climate action (Exec. Order No. 14008, 2021).

Environmental Health Sciences

Exposure assessment, toxicology, epidemiology, and risk assessment are interconnected approaches that play a vital role in the field of public health and environmental health:

Exposure assessment is a subfield that measures, characterizes, and models the frequency, magnitude, and contact duration of agents with an exposed population. Exposure assessments also evaluate the effectiveness of interventions and provide health professionals with information about the source, routes, and areas of uncertainty to help determine a course of action (CDC, 2022b).

Toxicology examines how harmful natural substances (toxins) or harmful artificial substances (toxicants) affect living organisms. The primary goal of toxicology is to assess the potential risks associated with exposure to various chemicals, including drugs, industrial products and by-products, environmental pollutants, pesticides, minerals, and metals. Toxicologists examine how these substances enter the body; how they are distributed, metabolized, and eliminated; and how they affect both organs and systems. The Agency for Toxic Substances and Disease Registry (ATSDR) develops toxicological profiles for hazardous materials, ranked by frequency, toxicity, and likelihood of human exposure. These “Tox Profiles” are extensively researched and peer reviewed. Nurses can access the current list of 275 substances at the ATSDR’s Substance Priority List.

Environmental epidemiology focuses on the links between environmental exposures and human health outcomes. Environmental epidemiologists identify potential environmental health hazards, quantify risk, and explore how different environmental factors, such as air and water pollution, chemicals, radiation, and climate change, impact health. The findings are used to inform public health policy, protect communities from risk, and develop interventions aimed at reducing exposures and improving population health.

Biomonitoring is a scientific methodology used to assess the presence and concentration of specific substances, such as chemicals and pollutants, in living organisms. Samples of blood, urine, saliva, hair, nails, and more may be utilized. Biomonitoring examines the extent of an individual’s or population’s exposure to environmental agents and uses this data to monitor the accumulation and impact of substances over time, identify potential health risks, inform regulations, and develop targeted interventions. The CDC runs a national biomonitoring program that measures the presence of over 400 chemicals at over 500 laboratories, and the agency has made numerous significant advances in improving population health, including the reduction of exposure to secondhand smoke and lead (CDC, 2022a).

Environmental burden is how public health professionals quantify and compare the impact of environmental risks on a population’s health. Climate change, air, noise, and water pollution are examples of environmental burdens because they have detrimental effects on the ecosystem and human health. This burden can manifest in a variety of ways, including increased rates of illness, disability, and premature death as well as decreased quality of life and productivity. Health indicators such as mortality rates, morbidity rates, and disability-adjusted life years (DALYs) are used to measure the impact of environmental hazards on human health and help identify vulnerable populations at risk. Environmental burden considers the cumulative impacts, or the total harm to humans resulting from the combination and interaction of multiple factors such as pollution, socioeconomics, and preexisting conditions. For example, the impact of respiratory illness on an individual living in a community with elevated air pollution will be greater than that on an individual living in a community with clean air.

Bioaccumulation refers to the gradual accumulation of contaminants, such as heavy metals like mercury and lead, within the tissues of living organisms. This process occurs as organisms consume contaminants from their surrounding environment more rapidly than they are able to eliminate or metabolize them. Instead of being excreted, the substances become stored in the organism’s body, leading to increased concentrations as the toxins accumulate. Over time, organisms higher up the food chain, such as humans, may consume food that contains these accumulated pollutants (EPA, 2021b).

A comprehensive approach is necessary to reduce environmental burden; approaches include addressing the underlying causes of environmental hazards, providing education to the public about hazards, and implementing policies to reduce exposure to environmental pollutants. The C/PHN assesses the reports and then works with regulatory agencies and industries to reduce emissions and waste, advocating for clean energy and transportation and supporting policies that protect vulnerable populations from environmental risks.