The Effects of Environmental Factors on General Human Health: A Scoping Review

Abstract

Background/Objectives: The external environment constantly influences human health through many factors, including air quality, access to green spaces, exposure to pollutants, and climate change. Contamination poses a substantial threat to human well-being; conversely, environmental factors also positively impact health. The purpose of this study is to provide a comprehensive review of the complex relationship between various environmental factors and human health. While individual studies have explored specific aspects, a broader integrative understanding is lacking. Methods: Through databases (PubMed, Cochrane, Copernicus), 4888 papers were identified, with 166 selected for detailed analysis. Results: We summarized recent research, identifying multiple associations between environmental factors such as air pollution, climate change, solar radiation, and meteorological conditions and their impact on various health outcomes, including respiratory, cardiovascular, metabolic and gastrointestinal, renal and urogenital, neurological and psychological health, infectious and skin diseases, and major cancers. We use chord diagrams to illustrate these links. We also show the interaction between different environmental factors. Findings begin with exploring the direct impact of environmental factors on human health; then, the interplay and combined effects of environmental factors, elucidating their (often indirect) interaction and collective contribution to human health; and finally, the implications of climate change on human health. Conclusions: Researchers and policymakers need to consider that individuals are exposed to multiple pollutants simultaneously, the "multipollutant exposure phenomenon". It is important to study and regulate environmental factors by considering the combined impact of various pollutants rather than looking at each pollutant separately. We emphasize actionable recommendations and solutions.

Keywords: Copernicus; environmental factors; geographical location; human health; meteorological factors; pollution.

Figure 1

Overview of the review process and classification of the literature using PRISMA 2020 flow diagram guidelines.

Figure 2

Impacts of major environmental factors (external environment) on human health (nine major categories with several diseases) (Abbreviations: COPD: chronic obstructive pulmonary disorder, IBS: irritable bowel syndrome, IBD: inflammatory bowel disease, GERD: PTSD: post-traumatic stress disorder, AE-IPF: acute exacerbation of idiopathic pulmonary fibrosis, ALRI: acute lower respiratory infections, BP: blood pressure).

Figure 3

Depicts positive associations between respiratory health issues and environmental factors. (AE-IPF: acute exacerbation of idiopathic pulmonary fibrosis, COPD: chronic obstructive pulmonary disease, ALRI: acute lower respiratory infections, PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, SO₂: sulfur dioxide, NO₂: nitrogen dioxide, O₃: ozone, CO: carbon monoxide).

Figure 4

Depicts positive associations between cardiovascular health issues and environmental factors (PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, SO₂: sulfur dioxide, NO₂: nitrogen dioxide, O₃: ozone, CO: carbon monoxide).

Figure 5

Depicts positive associations between metabolic and gastrointestinal health issues and environmental factors (GERD: gastroesophageal reflux disease, NMHC: non-methane hydrocarbons, CH₄: methane, PM_2.5: particulate matter smaller than 2.5 µg/m³, SO₂: sulfur dioxide, NO₂: nitrogen dioxide, O₃: ozone, CO: carbon monoxide).

Figure 6

Depicts positive associations between renal and urogenital health issues and environmental factors (PM_2.5: particulate matter smaller than 2.5 µg/m³, SO₂: sulfur dioxide, NO_x: nitrogen oxides, O₃: ozone, CO: carbon monoxide).

Figure 7

Depicts positive associations between neurological and psychological health issues and environmental factors (PTSD: Post-Traumatic Stress Disorder, PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, PM_0.1: particulate matter smaller than 0.1 µg/m³, NO₂: nitrogen dioxide, O₃: ozone).

Figure 8

Depicts positive associations between infectious diseases and environmental factors (PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³).

Figure 9

Correlates Cancer with environmental factors (PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, NO₂: nitrogen dioxide, O₃: ozone, UVB: ultraviolet B radiation, PAH: polycyclic aromatic hydrocarbon).

Figure 10

Correlates skin diseases with environmental factors (PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, NO₂: nitrogen dioxide, NO_x: nitrogen oxides, O₃: ozone, UV: ultraviolet radiation, DTR: diurnal temperature range).

Figure 11

Correlates other/miscellaneous diseases with environmental factors (PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, NO₂: nitrogen dioxide, NO_x: nitrogen oxides, O₃: ozone, CO: carbon monoxide, SO₂: sulfur dioxide, PAH: Polycyclic Aromatic Hydrocarbon).

Figure 12

Associations among environmental factors (UV radiation: ultraviolet radiation, PM_2.5: particulate matter smaller than 2.5 µg/m³, PM₁₀: particulate matter smaller than 10 µg/m³, SO₂: sulfur dioxide, NO₂: nitrogen dioxide, O₃: ozone, CO: carbon monoxide, PAH: polycyclic aromatic hydrocarbon).

Figure 13

Integrated public health risk assessment and response framework.