Allergic diseases are signalling a public health crisis — It is time for a global allergy health plan

Allergic conditions are signalling a public health crisis never seen before. In allergy, the environment is accused as the symptoms are heavily environment-dependent, food, pollen, animals etc. What happens as we evolve from nature — live while using it but unable to tolerate it anymore?

Inflammatory response without a reason

Allergic diseases and asthma indicate distorted immune regulation, which manifests itself by various inflammatory responses at the dermal and mucosal borders between the ecosystem of human body and the wider ecosystems. As a result, patients suffer from various skin, upper and lower airway, and conjunctival symptoms such as itching, swelling, mucus production, sneezing, blocked nose, cough, wheezing, breathlessness, gastrointestinal symptoms, and even life-threatening anaphylaxis. The immune response misreads the exposure by sensing harmless substances as a threat like proteins released by pollen. Consequently, an inflammatory response is triggered for defence. Clinical symptoms are suppressed by medication, and the severe inflammatory cascade, circulus vitiosus, even cut by biological therapeutics. Allergen-specific immunotherapy (AIT) helps patients to train their immune system not to overreact. The simple and safe sublingual and oral applications have increased the use.

Why is immune tolerance at stake?

In 2002, J-F Bach summarized the evidence that the increased prevalence of allergic and autoimmune diseases in industrialized countries over the preceding 30 years is caused by the reduction of the infectious diseases.¹ Now, it seems that the reasons for the increasing immune dysfunction are more complex.

In 2013, the Special Committee on Climate Change and Biodiversity of the World Allergy Organization (WAO) stated “that reduced biodiversity of the gut and skin microbiota (microbiome) is associated with various inflammatory conditions, including asthma, allergic and inflammatory bowel diseases (IBD), type1 diabetes, and obesity. The general microbial deprivation characterizing the lifestyle of urban people in affluent countries is a risk factor for immune dysregulation and impaired tolerance. The risk is further enhanced by physical inactivity and a western diet poor in fresh fruit and vegetables, which may act in synergy with dysbiosis of the gut flora”.²

Allergic conditions and asthma are only examples of a large group of chronic noncommunicable diseases (NCDs), which have been on the rise after World War II. These disorders share common features: microbial imbalance, long-term immune dysfunction, and a tendency to low-grade inflammation (Fig. 1).³ Individual genetic predisposition and epigenetic regulation modify the risk and type of manifestation of the clinical disease.

Fig. 1.

Allergy and asthma — manifesting so environment-dependent — are signalling a much wider public health crisis. The noncommunicable diseases are sharing common characteristics: microbial dysbiosis, immune dysfunction and tendency for inflammatory response.³ (reused from Haahtela et al. 2019, under https://creativecommons.org/licenses/).

In 2023, World Health Organisation (WHO) stated: “Tackling the rapidly growing global burden of NCDs constitutes one of the major challenges for development in the 21st century. During the first 2 decades, while global deaths due to communicable diseases declined those due to NCDs and mental health rapidly increased. The global share of NCD deaths among all deaths increased from 61% in 2000 to 74% in 2019”.⁴ Aging of the urban populations is only a part of the explanation.

What has changed?

The living environment and lifestyle have profoundly changed along with the cultural evolution in the fast-urbanizing world. It has provided a lot of common good, including health and safety, but is increasingly disconnecting us from the wider nature.⁵ The human body is an ecosystem dependent on the services of other ecosystems (Fig. 2).⁶ In 2025, WHO listed global targets to reduce the burden of NCDs. The targets deal with various risk factors like alcohol, physical inactivity, salt intake, smoking, and high blood pressure.⁷ Risk-thinking is fine, but it forgets the reverse side of the coin: the role of protective factors. They are derived from our evolutionary home, wider nature, which is a battlefield for survival but provides also long-term resilience. The invisible microbes and biogenic volatile organic compounds (BVOCS) are acquired by breathing, eating, drinking, and touching. Our senses guide us for safe connection. The importance of BVOCs, more than 1000 identified, has not been studied much but they regulate the cellular metabolism.⁸ Urban citizens live increasingly indoors breathing air-conditioned and filtrated air. The health effects of natural light are also significant. The living environment labels us mentally and socio-culturally.

Fig. 2.

Human body as a community of species and genomes. Biotically diverse exposure calls for epigenetic signalling to modify and adapt immune regulation for resilience. Interruption may degrade or improve resilience. (In the middle, the drawing Vitruvian Man by Leonardo da Vinci, from the end of 15th century. Human body is an expression of the microcosm connected to the macrocosm),⁶ (reused from Haahtela et al. 2021, under Creative Commons Attribution-NonCommercial License).

Modern, urbanized man is suffering from nature deficiency,⁹ which in medical practice might be compared with deficiencies in iron, vitamins, and hormones. The microbiome has impoverished even 30–84% on the skin of people in the developed world compared to our ancestors.¹⁰ We are losing “old friends”.¹¹ In the Finnish City of Turku, short-chain fatty acids in the stool samples of pregnant women, reflecting the gut microbial richness and diversity, collapsed in 20 years.¹² For diagnosis and treatment, validation of relevant biomarkers is called for, eg, 16S rDNA sequencing of the microbiota of skin swabs or measuring short-chain fatty acids from serum or stool samples. Probiotics and prebiotics, and even faecal transplants, are efforts to compensate the microbial deficiency, but they are as “needles in the haystack” compared to true nature contact.

Air pollution, chemicalization, and climate warming come on top of nature deficiency and are huge global problems compromising public health.

What to do?

In 2013, the WAO Special Committee on Climate Change and Biodiversity introduced behavioural means to induce immune tolerance. It also suggested an intervention, a Global Allergy Plan, to prevent and reduce the allergy burden. Such a plan took place in the Finnish Allergy Programme 2008–2018 emphasizing allergy health, tolerance, and nature connection with most favourable results¹³ and major cost savings.¹⁴ Now, 12 years later, the WAO suggestions are even more relevant and timely — not only to stop the allergy epidemic but to mitigate the public health crisis with the ever-increasing burden of NCDs. In the Finnish city of Lahti, the European Green Capital 2021, public health is promoted in parallel with measures against climate warming and nature loss. Especially, asthma, diabetes (type 1 and 2), obesity, and depression are followed 2022–2032.^15,16 The win-win setting is obvious, and the strategy accords with the Planetary Health concept, defined as the health of human civilization and the state of natural systems on which it depends.¹⁷

Understanding that biodiversity/nature loss is not only taking place in the wider environment but also in the human body led to the biodiversity hypothesis of allergy and health in general as reviewed in previous works.^2,18 WAO, EAACI, EFA, AAAAI, ACAAI, APAAACI, SLAAI, and other organizations of the allergy community could join forces for a Global Allergy Health Plan. Allergy is signalling an urgent need to reconcile the relationship of man and nature ‒ to go with nature, not against it (Fig. 3).¹⁹ Is there any stronger message to be sent to societies and healthcare for future and public health? The EAACI Guidelines and Recommendations of the preventive effects of environmental greenness, green space in allergy and asthma, are paving the way for the better.²⁰

Fig. 3.

Reaching for a healthier future,¹⁹ (modified from graphical abstract, with permission).

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Declaration of competing interest

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