Lancet Planetary Health最新文献

Background: Pregnant individuals are particularly susceptible to non-optimal temperatures due to their physiological status. Moreover, pregnancy is a crucial period for programming fetal health. Quantifying the impact of non-optimal temperature exposure and the contribution of anthropogenic climate change is crucial for mitigating and adapting to climate-related health risks. However, this has not been thoroughly studied in pregnant individuals in low-income and middle-income countries (LMICs).

Methods: Using data from 511 449 births across 31 LMICs from 1990 to 2018, we linked climate simulations (with and without anthropogenic forcing) to spatiotemporally resolved temperature data and birthweight records. We assessed the association between heat and cold exposure (ie, >90th and <10th percentile of temperature by region) during pregnancy and birthweight across different regions. We then used temperature simulations from both historically forced and natural-only forced climate models to estimate changes in exposure due to anthropogenic climate change and to quantify the burden of temperature-related low birthweight (ie, a birthweight <2500 g) attributable to anthropogenic climate change.

Findings: Heat exposure during pregnancy, compared with the optimal temperature range, was associated with an increased risk of low birthweight in several regions: southern Asia (odds ratio 1·41, 95% CI 1·34-1·48), western Africa (1·12, 1·02-1·24), and eastern Africa (1·40, 1·27-1·55). Cold exposure increased the risk of low birthweight in central Africa (1·31, 1·10-1·56), southern Africa (1·18, 1·02-1·36), and eastern Africa (1·14, 1·02-1·26). Anthropogenic climate change contributed to approximately 59·2% (95% CI 16·6-94·3), 89·0% (51·0-100·0), and 77·3% (27·0-100·0) of heat-related low birthweight cases in southern Asia, western Africa, and eastern Africa, respectively. Conversely, in regions where cold exposure was predominant, anthropogenic climate change reduced the burden of low birthweight.

Interpretation: Our study provides quantitative estimates of the contribution of anthropogenic climate change to the low birthweight burden in LMICs. These findings can inform strategies for climate mitigation and adaptation in LMICs and help reduce global health inequalities.

Funding: National Natural Science Foundation of China.

Background: Zika virus (ZIKV) outbreaks have raised major global health concerns recently, yet reported outbreaks are rare in Africa, where ZIKV was first discovered. Recent studies on Aedes aegypti, the mosquito that transmits ZIKV, might explain this phenomenon. The Ae aegypti subspecies present in Africa shows lower preference for biting humans and reduced susceptibility to ZIKV infection compared with the subspecies distributed outside Africa. Alternatively, climate might strongly limit transmission as it affects multiple traits of ZIKV and the mosquito vector.

Methods: We used a modelling approach informed by empirical data to assess ZIKV transmission risk across Africa. We fitted the model using data from laboratory experiments, and validated the model by comparing predicted transmission suitability with seroprevalence surveys conducted across Africa. Additionally, we used mosquito genetic and climate-based projections to map future ZIKV outbreak risk at 59 urban centres in Africa.

Findings: The model predictions partially and significantly explain historical patterns of ZIKV circulation in Africa (accounting for 46% of the variation in seroprevalence surveys). Mosquito population genetics influence transmission more strongly than climate through two mechanisms: vector-host contact and vector competence. If climate and mosquito genetic population projections are accurate and there are no other changes to drivers of Zika virus transmission in Africa, we predict that approximately three-quarters of the most populous African cities will be suitable for ZIKV outbreaks by the end of the century.

Interpretation: Both population-level genomic variation in mosquitoes and climate contribute to the lack of ZIKV outbreaks in Africa. Given the importance of mosquito genetics in driving this pattern, local genomic surveillance of mosquito populations would help predict outbreaks in vulnerable communities. This will become increasingly important with population growth, urbanisation, and climate change.

Funding: Princeton University, French Government's Investissement d'Avenir and France 2030 programmes, MSDAVENIR, and US National Institutes of Health.

Background: Ambient (outdoor) air pollutant exposures have emerged as a plausible risk factor for incident childhood asthma. However, the effect of ambient air pollutant exposures on risk of incident adult asthma is unclear. We aimed to investigate associations between specific ambient air pollutants and the risk of incident adult asthma.

Methods: In this systematic review and meta-analysis, we searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Web of Science from inception to Nov 27, 2023. We included observational studies with the outcome of new-onset asthma during adulthood (onset at ≥18 years), and metric of exposure of ambient air pollutants (particulate matter [PM]_2·5, nitrogen dioxide [NO₂], ozone [O₃], and sulphur dioxide [SO₂]). Study data were extracted independently by two reviewers and study quality was assessed using the Newcastle-Ottawa scale. When four or more eligible studies were available for a given pollutant, we applied meta-analysis using inverse variance weighting in a random effects model to estimate pooled relative risk (RR), and used meta-regression to explore sources of heterogeneity. The protocol was registered with PROSPERO, CRD42023420139.

Findings: Our search identified 1891 references. After excluding 651 (34%) duplicates and ineligible studies, we included 25 studies in the systematic review. After excluding studies with overlapping populations or reporting effect estimates that could not be pooled, we performed meta-analysis for PM_2·5 (nine studies), NO₂ (nine studies), and O₃ (four studies). Pooled random effects RRs for incident adult asthma per 5 μg/m³ increase in PM_2·5 were 1·07 (95% CI 1·01 to 1·13) and per 10 μg/m³ in NO₂ were 1·11 (1·03 to 1·20). We found no significant association between increasing O₃ concentration and incident adult asthma (per 60-μg/m³ increase in O₃, pooled RR 1·04 [0·79 to 1·36]). We found substantial heterogeneity across studies (I²=88% for all analyses). In exploratory meta-regression, average exposure level was a significant source of heterogeneity for the pooled NO₂ estimate (95% CI -0·0077 to -0·0025 per μg/m³).

Interpretation: Exposure to increased ambient PM_2·5 or NO₂ might present an additional risk factor for incident adult asthma, although high heterogeneity among included studies warrants caution in interpretation. Evidence was inconsistent for O₃ and insufficient for SO₂. To increase confidence and population representation in pooled estimates, further primary investigations are necessary, ideally with aligned methodology and reporting.

Funding: None.