12 sources: 3 meta-analyses, 9 systematic reviews
Environmental · Concept
Air Quality and Wellbeing
Air pollution exposure is linked to higher cardiovascular, diabetes and dementia risk; personal-scale habits that reduce exposure are not covered by the research reviewed here.
Beta content: this dimension's review set is version 0.9-beta and upgrades in place after the Round-2 internal reviews.
4 of 12 sources behind this entry were read from the abstract only; they are marked in the sources list.
Beginner-friendlyHome and neighborhood
Before you start
People with asthma/COPD should follow clinician guidance on air-quality thresholds.
When to seek a professional
- Worsening respiratory symptoms or suspected indoor contaminant (mold, CO): see a clinician / qualified home-inspection professional
Maintain good ventilation and limit exposure on poor-air-quality days
Optional: ventilation, air-quality monitor or forecast appFor most adultsCity dwellersRespiratory sensitivity
What the evidence says
What the sources say
The population-scale evidence is consistent: higher exposure to fine particulates and related pollutants is associated with greater cardiovascular, metabolic and dementia risk. Two things are weaker than they are often stated. Greenery is not straightforwardly good for airways, since allergenic pollen and respiratory irritation are among green space's documented downsides. And personal-scale ventilation habits are not covered in the research reviewed for this library at all. Reducing exposure is well justified; the specific household tactics are sensible rather than evidenced.
What we won't claim
- Houseplants or greenery purify indoor air enough to treat disease
- Clean air cures respiratory illness
12 sources: 3 meta-analyses, 9 systematic reviews
- Agreement
- Direction recorded for 0 of 12 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- No source states a certainty rating.
- How the sources were read
- Some sources are based on abstracts, not full texts.
What each source measured and concluded (12)
systematic review · 2025
Jones et al. (2025) — Environmental Risk Factors for All-Cause Dementia, Alzheimer's Disease Dementia, Vascular Dementia, and Mild Cognitive Impairment: An Umbrella Review and Meta-Analysis.
- What it measured
- Risk of all-cause dementia, Alzheimer's disease dementia, vascular dementia, and mild cognitive impairment from environmental risk factors
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Umbrella review and meta-analysis
- Studies and participants, as stated
- 19 reviews containing 37 meta-analyses
systematic review · 2025
Brown et al. (2025) — A systematic review of green gentrification and mental health.
- What it measured
- Mental health outcomes
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- N=16 articles
systematic review · 2024
Legg et al. (2024) — The effects of allergic pollen in green space on mental health, behaviour and perceptions: A systematic review
- What it measured
- Mental health, behaviour and perceptions related to allergenic pollen in green space
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- N=26 papers
systematic review · 2022
Sillman et al. (2022) — Do sex and gender modify the association between green space and physical health? A systematic review.
- What it measured
- Whether sex/gender modifies green space-physical health associations (CVD, cancer, diabetes, general physical health, respiratory disease, mortality, obesity-related)
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- N=62 articles (81 analyses)
systematic review · 2021
Rigolon et al. (2021) — Green Space and Health Equity: A Systematic Review on the Potential of Green Space to Reduce Health Disparities
- What it measured
- Physical health outcomes.
- How it measured it
- Descriptive statistics (means and standard deviations) of effect modification tests.
- How it was read
- read in full text
- What the review says it includes
- Systematic review of 90 articles
- Studies and participants, as stated
- N=90 studies; total participants not reported
meta-analysis · 2019
Rojas-Rueda et al. (2019) — Green spaces and mortality: a systematic review and meta-analysis of cohort studies
- What it measured
- All-cause mortality.
- How it measured it
- Hazard ratio (HR) and 95% CI.
- Its conclusion, in its own words
- “We found evidence of an inverse association between surrounding greenness and all-cause mortality. Interventions to increase and manage green spaces should therefore be considered as a strategic public health intervention.”
- How it was read
- read in full text
- What the review says it includes
- Meta-analysis of 9 cohort studies
- Studies and participants, as stated
- N=8,324,652 participants across 9 studies
- Heterogeneity, as stated
- Heterogeneity between studies due to different populations and buffer sizes.
systematic review · 2023
Liu et al. (2023) — The built environment and cardiovascular disease: an umbrella review and meta-meta-analysis.
- What it measured
- Cardiovascular disease (CVD) events in adults.
- How it measured it
- Objectively measured outcomes (prevalence, incidence, or mortality of CVD conditions).
- How it was read
- read in full text
systematic review · 2023
Aarthi et al. (2023) — Associations of the built environment with type 2 diabetes in Asia: a systematic review
- What it measured
- Type 2 diabetes prevalence and incidence.
- How it measured it
- Biomedical tests and registry records (objective).
- Its conclusion, in its own words
- “Our systematic review has identified several built environment characteristics, which were significantly related to T2D in Asia, in particular air pollution.”
- How it was read
- read in full text
- What the review says it includes
- Systematic review of 28 studies
- Studies and participants, as stated
- N=482,833 participants across 28 studies (note: this is the largest sample size mentioned for a single study, but the total sample size across all studies is not explicitly provided)
- Heterogeneity, as stated
- Heterogeneity in study design and outcome definitions
systematic review · 2021
Andersen et al. (2021) — Nature Exposure and Its Effects on Immune System Functioning: A Systematic Review
- What it measured
- Anti-inflammatory, anti-allergic, anti-asthmatic effects, and increased NK cell activity.
- How it measured it
- Serum cytokine levels (IL-6 and TNFα), immune cell subsets (NK cells and T cells), cytotoxic mediators (objective).
- How it was read
- read in full text
- What the review says it includes
- Systematic review of 33 studies (20 human, 13 animal intervention studies)
- Studies and participants, as stated
- N=not reported participants across 33 studies
meta-analysis · 2021
Smith et al. (2021) — Urban blue spaces and human health: a systematic review and meta-analysis of quantitative studies
- What it measured
- Obesity.
- How it measured it
- Body Mass Index (BMI) (objective).
- How it was read
- read in full text
- What the review says it includes
- Systematic review with meta-analysis of 14 studies
- Studies and participants, as stated
- N=2,067,382 participants across 25 studies
- Heterogeneity, as stated
- High heterogeneity in blue space exposure and health outcome assessments.
- Heterogeneity, as stated
- Potential underestimation of effect sizes due to heterogeneity.
meta-analysis · 2023
Houweling et al. (2023) — The effect of the urban exposome on COVID-19 health outcomes: A systematic review and meta-analysis.
- What it measured
- COVID-19 health outcomes (infection severity, hospitalization, ICU admission, COVID pneumonia, mortality)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis (of ecological and non-ecological observational studies)
- Studies and participants, as stated
- 279 studies (38 non-ecological and 241 ecological)
systematic review · 2019
Schüle et al. (2019) — Social Inequalities in Environmental Resources of Green and Blue Spaces: A Review of Evidence in the WHO European Region
- What it measured
- Social inequalities in availability and accessibility of green and blue spaces
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- 14 studies (2010-2017)
Key sources (12)
Every source below is shown with its study design and links to the original study. This is the audit trail.
systematic reviewEnvironmental Risk Factors for All-Cause Dementia, Alzheimer's Disease Dementia, Vascular Dementia, and Mild Cognitive Impairment: An Umbrella Review and Meta-Analysis.
systematic reviewA systematic review of green gentrification and mental health.
systematic reviewThe effects of allergic pollen in green space on mental health, behaviour and perceptions: A systematic review
systematic reviewDo sex and gender modify the association between green space and physical health? A systematic review.
systematic reviewGreen Space and Health Equity: A Systematic Review on the Potential of Green Space to Reduce Health Disparities
meta-analysisGreen spaces and mortality: a systematic review and meta-analysis of cohort studies
systematic reviewThe built environment and cardiovascular disease: an umbrella review and meta-meta-analysis.
systematic reviewAssociations of the built environment with type 2 diabetes in Asia: a systematic review
systematic reviewNature Exposure and Its Effects on Immune System Functioning: A Systematic Review
meta-analysisUrban blue spaces and human health: a systematic review and meta-analysis of quantitative studies
meta-analysisThe effect of the urban exposome on COVID-19 health outcomes: A systematic review and meta-analysis.
systematic reviewSocial Inequalities in Environmental Resources of Green and Blue Spaces: A Review of Evidence in the WHO European Region
“Abstract only” means the review read that paper’s abstract, not its full text; “screened only” means it was included at re-screening and not extracted. Both stay in the trail with their DOI, because how a source was read is part of the audit.
Explore all 401 studies in Environmental →
The full evidence base this focus area draws on, every study with its design and DOI.What it is for
Lower my long-term disease risk