2022 World Health Day: Why we need climate action at the center of human health?

As we left March and the second anniversary of the pandemic behind, April appears as an ideal opportunity to reflect on global health and how our wellbeing is intrinsically linked to our mother earth and the treatment we give it. 

This year, World Health Day centers on the interdependence between humans health and environmental health¹. Our species’ existence evolved from and depends on healthy ecosystems, so why are we handling health and environmental conservation as two separate issues?

If there is anything COVID-19 came to teach us, it’s that we are deeply interconnected. And we are not only talking about the interdependence with our peers and how, in a globalized world, the problem of one is undoubtedly the problem of all, but about how environmental devastation bounces right back to us.

“It’s taken a pandemic to help us realize just how sick our world has become,” starts a video from the World Health Organization promoting well-being and sustainable development². Human recklessness is counted in human lives.

The hard truth: How environmental problems actually affect our health

Air pollution diseases

Mainly generated by human activity, air pollutants are particles of ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide (and others) that endanger the well-being of all who has contact with it, whether it is a living being or the environment itself. Right now, 130 million people in the US are breathing unhealthy levels of ozone smog³.

Air pollution exposure is associated with oxidative stress and inflammation in human cells, leading to conditions such as⁴:

• Respiratory disease:  air pollution can affect lung development and is implicated in the development of emphysema, asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease and acute lower respiratory infections in children.
• Cardiovascular disease: fine particulate matter can impair blood vessel function and speed up calcification in arteries, contributing to ischemic heart disease, stroke, and chronic obstructive pulmonary disease (COPD).
• Cancer: lung cancer is the uncontrolled division of cells within the lungs, and it is associated with air pollutants, especially particulate matter pollution and secondhand smoke. A large study of more than 57,000 women found that living near major roadways may increase a woman’s risk for breast cancer⁵.

Water contamination diseases

According to WHO, at least 2 billion people around the world drink water from a contaminated source⁶. 

Contaminants in water can lead to adverse health effects⁷, including gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and people whose immune systems are compromised because of AIDS, chemotherapy, or transplant medications may be especially susceptible to illness from some contaminants.

Microbiologically contaminated drinking water can transmit diseases such as:

• Diarrhea and cholera: although most cases clear on their own, some infections may need antibiotics, like cholera. Severe cases can cause enough dehydration to require intravenous fluids. Water contamination causes around 485,000 diarrhoeal deaths each year.
• Polio: this disabling and life-threatening disease caused by the poliovirus can be spread by eating raw food or drinking water contaminated with an infected person’s feces. Most people with polio do not feel sick.

Climate change diseases

Global warming has various effects on human health. The main indirect effects are on infectious diseases⁸ such as malaria and dengue:

• Malaria: while the disease is uncommon in temperate climates, malaria is still common in tropical and subtropical countries. Each year, nearly 290 million people are infected with malaria and more than 400 thousand die from it.
• Dengue fever: the global incidence of dengue has grown dramatically, with about half of the world’s population now at risk. 100-400 million infections occur each year; luckily, over 80% are generally mild and asymptomatic.
• Heatstroke⁹: although global warming has created milder winters, hotter temperatures bring along higher death rates during heat waves, with causes ranging from heat stroke and related conditions to cardiovascular disease, respiratory disease, and cerebrovascular disease.

Climate change impact varies depending on the location and countries’ socioeconomic situations, with developing nations being the most affected. 

Deforestation diseases

Over the past two decades, scientific evidence has suggested that deforestation creates the conditions for a range of deadly pathogens to spread to people.

By changing the structure of the forests,  we invade wildlife habitats and expose ourselves to animal-hosted viruses. Nearly 1 in 3 outbreaks of new diseases are directly linked to human-driven land devastation.

Not only malaria and other mosquitoes-transmitted diseases are within that list; in fact, 60% of new infectious diseases —including HIV, Ebola, and Nipah, all of which originated in forest-dwelling animals—are transmitted by a range of other wildlife animals.

Even before COVID-19 occurred (1)(2), scientists were concerned about how these outbreaks exacerbated by human alteration of landscapes could cause the next pandemic.

“It’s a numbers game: The more we degrade and clear forest habitats, the more likely it is that we’re going to find ourselves in these situations where epidemics of infectious diseases occur.”

— Andy MacDonald, a disease ecologist at the Earth Research Institute of the University of California, Santa Barbara.

Previous efforts and initiatives

The “One Health” concept 

In 2007, the American Veterinary Medical Association (AVMA), supported by the American Medical Association and the American Public Health Association, established a One Health Initiative Task Force (OHITF) with the purpose of promoting cooperation among health science professions, academic institutions, and governmental agencies to help with the prevention of cross-species disease transmission ¹⁰.

As stated in its founding white paper, these efforts hoped to prevent the next great pandemic. As we all now know, we failed to avoid it even with a decade’s warning in advance¹¹.

Even back then, experts agreed that degradation of the environment would continue to create favorable settings for the expansion of existing infectious diseases and an increasing number of acute and chronic non-infectious diseases¹².

Healthy Environment, Healthy People

In 2015,  the United Nations General Assembly launched the 2030 Agenda for Sustainable Development: a collection of 17 interlinked global goals designed to be a “blueprint to achieve a better and more sustainable future for all”, as expressed in an official resolution published in 2017¹³.

The Healthy Environment, Healthy People goal of the project highlights critical links between development, the environment, human well-being and the full enjoyment of a wide range of human rights, including the rights to life, health, food, water and sanitation. 

Besides, investing in environmental sustainability is a win-win: a biologically safer world can serve as an insurance policy for health and human well-being.

To “ensure healthy lives and promote well-being for all at all ages” (SDG3) cannot be achieved over the long term without explicit action on terrestrial ecosystems (SDG15), oceans (SDG14), cities (SDG11), water and sanitation (SDG6).

“The challenges are interdependent and so are the solutions” 

We are on the brink of a health care revolution in which disease prevention strategic planning is finally understood as a complex entity including humans, animals, and their surroundings.

Even when we have new technologies on our side now, the most important advancement comes from within: contemporary health cannot be based on old-fashion strategies and outdated mindsets ¹⁴.

Jonathan Jennings and Dr. ​​Kinari Webb, founders of Health In Harmony —a nonprofit focused on raising awareness about the link between rainforests and humanity’s survival— listed three pending to do’s on this matter:

Changing our mindset: We need to expand how we comprehend human health. In theory and practice, global health must stop being so human-centered and expand to encompass our interdependence with nature.

Combining global health and environmental conservation:  The world requires health policymakers and global conservation practitioners to work together instead of having a separate agenda. In other words, states, companies, nonprofits and citizens alike must commit to act not only to fulfill their own goals¹⁵.

Taking real action on the interconnected challenges faced by people and the planet. Funding and infrastructure are needed to turn efforts into policies, and that can only be achieved with the support of governments and related institutions. Laws, policies, and pledges must be put into practice solely to protect the planet. 

Understanding and implementing the One Health concept, claiming for a coordinated response to human, animal and environmental health, cannot wait if we want to prevent the world from experiencing a coronavirus-like crisis all over again¹⁶.

1. World Health Organization. (2022). World Health Day 2022. [Online]. Available at: https://www.who.int/campaigns/world-health-day/2022.
2. World Health Organization. (2022). Health Promotion for Well-being, Equity and Sustainable Development. [February 22nd]. [Online]. Available at:

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3. Natural Resources Defense Council. (2021). Air Pollution 101: Our Health and Climate at Risk. [April 18th]. [Online]. Available at:

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4. Camfil. (2018). Diseases Caused By Air Pollution – Risk Factors and Control Methods. [February 9th]. [Online]. Available at: https://cleanair.camfil.us/2018/02/09/diseases-caused-by-air-pollution-risk-factors-and-control-methods/.
5. Cheng, I. (2019). Association between ambient air pollution and breast cancer risk: The multiethnic cohort study. PubMed. [April 25th]. [Online]. Available at: https://pubmed.ncbi.nlm.nih.gov/30924138/.
6. World Health Organization. (2022). Drinking-water. [March 21st]. [Online]. Available at: https://www.who.int/news-room/fact-sheets/detail/drinking-water.
7. Centers for Disease Control and Prevention. (2014). Water-related Diseases and Contaminants in Public Water Systems. [April 7th]. [Online]. Available at: https://www.cdc.gov/healthywater/drinking/public/water_diseases.html.
8. National Library of Medicine. (2010). The Effect of Global Warming on Infectious Diseases. [December 7th]. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3766891/.
9. Centers for Disease Control and Prevention. (2020). Temperature Extremes. [December 21st]. [Online]. Available at: https://www.cdc.gov/climateandhealth/effects/temperature_extremes.html.
10. American Veterinary Medical Association. (2008). One Health: A New Professional Imperative. [July 15th]. [Online]. Available at: https://www.avma.org/sites/default/files/resources/onehealth_final.pdf.
11. Foster, R. (2021). One Health Pandemic Prevention and Mitigation: The Role of FDA. The Food and Drug Law Institute. [Online]. Available at: https://www.fdli.org/wp-content/uploads/2021/10/6-Riley.pdf.
12. American Veterinary Medical Association. (2008). One Health: A New Professional Imperative. [July 15th]. [Online]. Available at: https://www.avma.org/sites/default/files/resources/onehealth_final.pdf.
13. United Nations. (2017). Resolution adopted by the General Assembly on 6 July 2017. [July 10th]. [Online]. Available at: https://upload.wikimedia.org/wikipedia/commons/9/9d/A_RES_71_313_E.pdf.
14. American Veterinary Medical Association. (2008). One Health: A New Professional Imperative. [July 15th]. [Online]. Available at: https://www.avma.org/sites/default/files/resources/onehealth_final.pdf.
15. Jennings, J. and Webb, K. (2021). What will it take to save the planet? Embracing interdependence. The Hill. [September 9th]. [Online]. Available at: https://thehill.com/opinion/energy-environment/571464-what-will-it-take-to-save-the-planet-embracing-interdependence/.
16. Foster, R. (2021). One Health Pandemic Prevention and Mitigation: The Role of FDA. The Food and Drug Law Institute. [Online]. Available at: https://www.fdli.org/wp-content/uploads/2021/10/6-Riley.pdf.