‘Air pollution is a pervasive environmental determinant of health’

Human health, in both men and women, is shaped by a complex interplay of biological, lifestyle and environmental factors that influence overall wellbeing and reproductive potential. While both sexes share many common health determinants – such as nutrition, stress and physical activity – there are also key physiological and hormonal differences that uniquely affect fertility. Understanding these distinctions and how they interact with age, genetics and modern lifestyles is essential for addressing reproductive challenges and promoting long-term health for men and women.

Growing evidence demonstrates that ambient quality and Indoor Air Quality (IAQ) significantly influence reproductive outcomes, particularly in Assisted Reproductive Technologies (ART), such as In Vitro Fertilisation (IVF). Pollutants, including fine particulate matter (PM₂.₅ and PM₁₀), nitrogen oxides, ozone, Volatile Organic Compounds (VOCs) and ultrafine particles, have been implicated in impaired gamete quality and embryo development.

Air pollution is a pervasive environmental determinant of health with established systemic impacts. Within reproductive medicine, growing research links exposure to airborne pollutants to reduced fertility, adverse pregnancy outcomes and diminished IVF success rates. The effects are mediated not only through oxidative and inflammatory damage to reproductive tissues but also via epigenetic remodelling processes that affect gamete competence and early embryogenesis.

Several large-scale cohort and registry studies have demonstrated associations between ambient air pollution exposure and reduced IVF outcomes. Choe et al. (2018) reported that higher PM₂.₅ exposure during ovarian stimulation and embryo culture correlated with decreased clinical pregnancy rates. Similarly, Wang et al. (2019) observed that increased particulate and nitrogen oxide exposure during embryo culture reduced implantation and live birth rates. Boulet et al. (2019) and Bertin et al. (2022) provided complementary findings from population-based data, indicating that pollutant exposure around oocyte retrieval and embryo transfer impairs IVF success. The most robust associations have been observed when exposures are temporally aligned with the peri retrieval or in vitro culture windows (Leathersich et al., 2025), underscoring the vulnerability of these critical developmental periods. Importantly, investigations have demonstrated that improving laboratory air filtration systems results in measurable improvements in fertilisation and implantation rates (Wang et al., 2019; Choe et al., 2018), suggesting causality.

Air pollutants induce oxidative stress and inflammation within the reproductive microenvironment, disrupting mitochondrial function, redox signalling and one-carbon metabolism. These perturbations alter the activity of chromatin-modifying enzymes, resulting in DNA methylation changes, histone modifications and dysregulation of non-coding RNAs. Gaskins et al. (2023) and Xu et al. (2025) have shown that exposure to air pollution can lead to aberrant methylation in granulosa cells and spermatozoa, potentially impairing oocyte and embryo competence. Van den Berg et al. (2024) further identified methylation alterations in placental tissue associated with prenatal exposure to fine particulates, reinforcing a mechanistic link between environmental exposure, epigenetic dysregulation and early developmental impairment.

IVF laboratories represent controlled environments where air quality can be systematically optimised. Esteves et al. (2019) emphasised the importance of HEPA and activated-carbon filtration, positive-pressure cleanrooms and zoning within HVAC systems to reduce exposure to PM and VOCs. Continuous monitoring of PM₂.₅, VOCs, CO₂ and humidity has been adopted as a best practice to ensure stable conditions for gamete and embryo culture. Operational measures – such as using low-VOC consumables, minimising personnel movement and performing pre/post-retrofit performance audits – have been associated with improved fertilisation and implantation outcomes (Esteves et al., 2019; Wang et al., 2019).

The emerging field of reproductive epigenomics offers promising biomarkers for assessing the biological effects of environmental exposure on fertility. Candidate applications include granulosa-cell DNA methylation profiling, sperm methylome and small RNA analyses and non-invasive embryo culture media assays. These biomarkers could serve as early indicators of gamete quality or as quality-control tools linked to air quality metrics (Gaskins et al., 2023; Xu et al., 2025). While the translational potential is significant, challenges remain in assay standardisation, reference range definition and longitudinal validation (van den Berg et al., 2024).

To strengthen causal inference and clinical utility, future research should focus on high-resolution exposure assessments combining personal and laboratory monitoring with IVF outcome data (Leathersich et al., 2025; Bertin et al., 2022). Randomised or quasi-experimental studies testing air quality retrofits in IVF clinics, coupled with embedded epigenetic analyses, will help validate environmental interventions. Concurrently, the development of clinical-grade assays for granulosa and sperm epigenetic profiling will enable the integration of molecular biomarkers into precision IVF strategies.

In conclusion, current evidence supports a mechanistic framework in which poor indoor and outdoor air quality reduces IVF success through oxidative and epigenetic disruption of gametes and embryos. Integrating rigorous IAQ control systems with validated epigenetic biomarkers may enhance IVF success rates, offering a translational pathway towards precision environmental management in reproductive medicine.

References

Choe SA, Jun YB, Lee WS, Kim SY, Kim YJ. Ambient air pollution exposure and clinical pregnancy rates after IVF. Hum Reprod. 2018;33(6):1071–1079.

Wang X, Chen C, Zhang Z, et al. Association between ambient air pollution and IVF outcomes during embryo culture. Hum Reprod. 2019;34(12):2451–2460.

Boulet SL, et al. Ambient air pollution and in vitro fertilization outcomes. Hum Reprod. 2019;34(12):2401–2411.

Bertin M, et al. Ambient air pollution and IVF outcomes: A nationwide study. BMJ Open. 2022;12:e056982.

Leathersich SJ, et al. Spatial and temporal air pollution exposure and IVF outcomes. Hum Reprod. 2025;40(3):512–523.

Gaskins AJ, et al. Environmental exposures and reproductive epigenetics: Current evidence and future directions. Clin Epigenetics. 2023;15:88.

Xu J, et al. Mechanistic insights into air pollution-induced epigenetic alterations in reproductive tissues. Reprod Toxicol. 2025;120:108578.

van den Berg E, et al. Air pollution, placental methylation, and developmental outcomes. Clin Epigenetics. 2024;14:51.

Esteves SC, et al. Laboratory air quality control in IVF: Practical recommendations. Reprod Biomed Online. 2019;38(6):879–890.