The environmental determinants of health are increasingly recognised with descriptions of higher hospital admissions and poorer outcomes for patients during periods of low air quality. Older adults are known to be especially prone to adverse health events during extremes of temperature but the acute impact of poor air quality is less well known. PIONEER has curated a highly granular dataset of 3,175,299 admissions for patients aged 65 and over, linking DEFRA air pollution data to patients' registered addresses. It includes demographics, admission details, diagnostic codes (ICD-10 & SNOMED-CT), respiratory data, medications, and presenting complaints. This dataset enables analysis of the short- and long-term impacts of air quality on health outcomes, providing a unique resource for research in environmental health, epidemiology, and multidisciplinary studies. Covering admissions from 01-01-2000 to 31-08-2023, it offers opportunities to expand to other timelines or include all age groups if required. Geography: The West Midlands (WM) has a population of 6 million & includes a diverse ethnic & socio-economic mix. UHB is one of the largest NHS Trusts in England, providing direct acute services & specialist care across four hospital sites, with 2.2 million patient episodes per year, 2750 beds & > 120 ITU bed capacity. UHB runs a fully electronic healthcare record (EHR) (PICS; Birmingham Systems), a shared primary & secondary care record (Your Care Connected) & a patient portal “My Health”. Data set availability: Data access is available via the PIONEER Hub for projects which will benefit the public or patients. This can be by developing a new understanding of disease, by providing insights into how to improve care, or by developing new models, tools, treatments, or care processes. Data access can be provided to NHS, academic, commercial, policy and third sector organisations. Applications from SMEs are welcome. There is a single data access process, with public oversight provided by our public review committee, the Data Trust Committee. Contact pioneer@uhb.nhs.uk or visit www.pioneerdatahub.co.uk for more details. Available supplementary data: Matched controls; ambulance and community data. Unstructured data (images). We can provide the dataset in OMOP and other common data models and can build synthetic data to meet bespoke requirements. Available supplementary support: Analytics, model build, validation & refinement; A.I. support. Data partner support for ETL (extract, transform & load) processes. Bespoke and “off the shelf” Trusted Research Environment (TRE) build and run. Consultancy with clinical, patient & end-user and purchaser access/ support. Support for regulatory requirements. Cohort discovery. Data-driven trials and “fast screen” services to assess population size.