Public health, heat illness & disease vectors KPIs by sector (with ranges)

Extreme heat killed more people globally than any other weather hazard in 2024, while vector-borne diseases expanded into regions previously considered temperate. For founders building climate adaptation solutions, understanding which public health KPIs actually predict outcomes (and which create a false sense of progress) has become essential for product development, fundraising, and market positioning.

The Stakes: Why These KPIs Matter Now

The Lancet Countdown on Health and Climate Change reported that heat-related mortality among people over 65 increased by 85% between 2000-2004 and 2018-2022 globally. In the UK specifically, the Office for National Statistics recorded approximately 4,500 excess deaths during the summer of 2022, when temperatures exceeded 40 degrees Celsius for the first time in recorded history. The UK Health Security Agency projects that heat-related deaths could triple by 2050 under a medium emissions scenario, rising from approximately 2,000 annually to over 7,000.

The economic burden is equally stark. Public Health England estimated that heat-related healthcare costs and lost productivity totalled 1.4 billion pounds annually as of 2024, with projections reaching 3.8 billion pounds by 2040. Meanwhile, dengue fever cases in Europe surged to 4,900 in 2024, with the Asian tiger mosquito (Aedes albopictus) now established in southern England. The UK Health Security Agency confirmed 12 locally acquired dengue cases in 2025, a threshold that would have seemed implausible a decade ago.

For founders, these trends represent both a moral imperative and a market opportunity. The global climate adaptation market is projected to reach $2 trillion annually by 2030, with public health adaptation comprising an estimated 15-20% of that total. But capturing value requires moving beyond vanity metrics (number of heat alerts issued) to outcome-oriented KPIs that demonstrate measurable health impact.

Key Concepts

Heat-Health Action Plans (HHAPs) are structured response frameworks that define temperature thresholds, alert levels, and coordinated interventions across health services, local authorities, and emergency responders. The World Health Organization recommends HHAPs as the primary institutional mechanism for reducing heat mortality. Effective HHAPs reduce excess mortality during heatwaves by 30-70% compared to regions without coordinated plans, according to a 2024 meta-analysis published in Environmental Health Perspectives.

Wet Bulb Globe Temperature (WBGT) integrates air temperature, humidity, wind speed, and radiant heat into a single metric that better predicts human physiological stress than dry bulb temperature alone. WBGT thresholds drive occupational health regulations across sectors, with the Health and Safety Executive recommending activity modification above 28 degrees WBGT for moderate physical work. The distinction matters: a dry bulb temperature of 32 degrees Celsius at 80% humidity produces a WBGT of approximately 31 degrees, well into the danger zone for outdoor workers, while the same temperature at 30% humidity yields a WBGT of roughly 25 degrees.

Climate-Sensitive Disease Surveillance encompasses monitoring systems that integrate epidemiological data with climate variables (temperature, precipitation, humidity) to predict disease outbreak timing and geographic spread. For vector-borne diseases, surveillance systems track both human cases and vector populations, enabling pre-emptive interventions such as targeted larviciding or public awareness campaigns. The European Centre for Disease Prevention and Control operates VectorNet, mapping vector distribution across 42 countries.

Thermal Inequity refers to the disproportionate heat exposure experienced by vulnerable populations including outdoor workers, elderly residents in poorly insulated housing, and communities in urban heat islands. Thermal inequity metrics disaggregate heat exposure by socioeconomic status, housing quality, and neighbourhood characteristics, revealing that the most deprived communities experience 2-4 degrees Celsius higher peak temperatures than affluent areas within the same city.

The 7 KPIs That Matter

1. Heat-Related Excess Mortality Rate

Definition: Additional deaths during heatwave periods compared to baseline mortality, expressed per 100,000 population.

Region Type	Bottom Quartile	Median	Top Quartile
Major UK Cities	>12 per 100K	6-12 per 100K	<6 per 100K
Rural/Coastal UK	>8 per 100K	4-8 per 100K	<4 per 100K
EU Metropolitan	>15 per 100K	8-15 per 100K	<8 per 100K
South/Southeast Asia	>25 per 100K	12-25 per 100K	<12 per 100K

Measurement critical: Excess mortality requires careful baseline construction accounting for age structure, seasonal patterns, and multi-year trends. Raw death counts during heatwaves overstate heat attribution by 20-30% unless adjusted for these confounders.

2. Emergency Department Heat-Related Presentations

Definition: Rate of heat-related emergency visits (heat exhaustion, heatstroke, dehydration, exacerbation of cardiovascular and respiratory conditions) per 100,000 population during alert periods.

Sector	Below Average	Average	Above Average	Top Quartile
NHS Acute Trusts	>85 per 100K	45-85 per 100K	20-45 per 100K	<20 per 100K
Occupational Health (Outdoor)	>120 per 100K workers	60-120 per 100K	25-60 per 100K	<25 per 100K
Care Home Residents	>150 per 100K	80-150 per 100K	35-80 per 100K	<35 per 100K

3. Heat Alert Response Time

Definition: Time from meteorological trigger to activation of health protection interventions at local level.

Response Component	Poor	Adequate	Good	Excellent
Alert Dissemination	>6 hours	3-6 hours	1-3 hours	<1 hour
Cooling Centre Activation	>12 hours	6-12 hours	2-6 hours	<2 hours
Vulnerable Population Contact	>24 hours	12-24 hours	6-12 hours	<6 hours
Healthcare Surge Staffing	>48 hours	24-48 hours	12-24 hours	<12 hours

4. Vector Surveillance Coverage Index

Definition: Proportion of at-risk geographic areas with active entomological surveillance, weighted by population density and climate suitability for vector establishment.

Region	Bottom Quartile	Median	Top Quartile
UK (Aedes monitoring)	<15%	15-40%	>40%
Southern EU (endemic areas)	<40%	40-70%	>70%
Tropical (established vectors)	<25%	25-55%	>55%

5. Building Overheating Hours

Definition: Annual hours above 28 degrees Celsius in residential buildings and above 26 degrees in care settings, measured per CIBSE TM59 methodology.

Building Type	Poor	Below Average	Average	Good
New-Build Homes (CIBSE TM59)	>100 hours	50-100 hours	20-50 hours	<20 hours
Existing Social Housing	>200 hours	100-200 hours	40-100 hours	<40 hours
Care Homes/Hospitals	>50 hours	25-50 hours	10-25 hours	<10 hours
Schools	>80 hours	40-80 hours	15-40 hours	<15 hours

6. Outdoor Worker Heat Exposure Compliance

Definition: Percentage of outdoor work hours where WBGT monitoring, rest schedules, and hydration protocols meet HSE guidance thresholds.

Sector	Bottom Quartile	Median	Top Quartile
Construction	<30%	30-60%	>60%
Agriculture	<20%	20-50%	>50%
Utilities/Infrastructure	<40%	40-65%	>65%
Events/Leisure	<25%	25-55%	>55%

7. Climate-Health Early Warning Accuracy

Definition: Positive predictive value of integrated climate-health warning systems for disease outbreaks and heat-health emergencies.

System Type	Below Average	Average	Above Average
Heat-Mortality Forecasting	<50% PPV	50-70% PPV	>70% PPV
Vector-Borne Disease Alerts	<30% PPV	30-55% PPV	>55% PPV
Air Quality-Health Warnings	<45% PPV	45-65% PPV	>65% PPV

What's Working

NHS Heat-Health Alert System Redesign

The UK Health Security Agency restructured its heat-health alert system in 2023, moving from a four-tier to an integrated impact-based approach aligned with Met Office weather warnings. The redesign reduced average alert-to-action time from 8 hours to under 3 hours across NHS trusts, with 78% of acute trusts activating surge protocols within the target window during summer 2024. Critical to success was the integration of patient-level vulnerability data from GP registries, enabling targeted outreach to high-risk individuals. During the July 2024 heatwave, trusts using the integrated system recorded 22% fewer heat-related emergency admissions compared to those still operating on legacy protocols.

Barcelona Superblock Model and Heat Mortality

Barcelona's superblock urban redesign programme, which converts clusters of city blocks into low-traffic, high-vegetation zones, has produced measurable public health outcomes. A 2024 study in The Lancet Planetary Health found that completed superblocks reduced ambient temperatures by 2.3 degrees Celsius on average and reduced heat-related mortality by 36% within their boundaries compared to adjacent conventional blocks. The programme also reduced NO2 concentrations by 25%, providing co-benefits for respiratory health. The model is now being replicated in Manchester and Bristol through the UK's Healthy Streets initiative.

Singapore's National Environment Agency Vector Control

Singapore's integrated vector management programme combines AI-powered mosquito population modelling, community-based surveillance through the myENV app (with 1.2 million active users), and targeted Wolbachia-infected mosquito releases. The programme reduced dengue incidence by 64% between 2020 and 2024, despite regional increases across Southeast Asia. The KPI framework tracks mosquito population indices at 68,000 monitoring points weekly, with automated escalation when the Aedes House Index exceeds 2% in any planning area.

What's Not Working

Fragmented Data Systems Across Health and Climate Agencies

The largest barrier to effective climate-health KPI measurement is data fragmentation. In the UK, heat-related health outcomes are recorded across multiple systems: NHS Digital for hospital admissions, ONS for mortality, HSE for occupational incidents, and local authority environmental health teams for community-level responses. No unified dashboard exists. A 2024 National Audit Office review found that 62% of local authorities lacked the technical capability to link climate exposure data with health outcomes, making meaningful KPI tracking impossible at the local level where interventions are delivered.

Overreliance on Temperature Thresholds Without Contextual Factors

Most heat alert systems trigger at fixed temperature thresholds, ignoring cumulative exposure, humidity, building characteristics, and population vulnerability. Research published in Nature Medicine in 2024 demonstrated that heat-related mortality begins increasing at temperatures 4-6 degrees Celsius below official alert thresholds when humidity is high and nighttime temperatures remain elevated. Systems relying solely on daytime maximum temperature miss approximately 40% of high-risk periods.

Inadequate Funding for Vector Surveillance Expansion

Despite the documented northward expansion of disease-carrying mosquitoes into the UK, vector surveillance budgets have not kept pace. The UK Health Security Agency's mosquito monitoring programme covers fewer than 50 fixed trap locations across England and Wales, compared to over 3,000 in France and 1,800 in Germany. This sparse network means that vector establishment could go undetected for months, undermining the early warning KPIs that public health strategies depend upon.

Action Checklist

• Audit existing heat-health data systems for integration gaps between climate, health, and social care datasets
• Implement WBGT monitoring (not just dry bulb temperature) at outdoor work sites and vulnerable care settings
• Establish building overheating monitoring using TM59-compliant sensors in social housing and care facilities
• Deploy disaggregated heat exposure mapping to identify thermal inequity hotspots within your service area
• Integrate GP patient vulnerability registries with weather alert systems for targeted outreach during heatwaves
• Expand vector surveillance networks to cover climate-suitable habitat areas identified by UKRI climate projections
• Set outcome-based KPI targets (mortality reduction, admission avoidance) rather than process metrics (alerts issued)
• Commission independent verification of heat-health intervention effectiveness using quasi-experimental designs

Sources

• Romanello, M., et al. (2024). The 2024 Report of the Lancet Countdown on Health and Climate Change. The Lancet, 404(10465), 2075-2128.
• Office for National Statistics. (2024). Excess Mortality During Heat Periods: England and Wales, 2022-2024. London: ONS.
• UK Health Security Agency. (2025). Heat-Health Alert System: Performance Report 2024. London: UKHSA.
• Mueller, N., et al. (2024). Health Impact Assessment of Barcelona Superblocks: Mortality, Morbidity, and Thermal Comfort Outcomes. The Lancet Planetary Health, 8(3), e142-e151.
• European Centre for Disease Prevention and Control. (2025). Vector-Borne Disease Surveillance Annual Report 2024. Stockholm: ECDC.
• Singapore National Environment Agency. (2025). Integrated Vector Management Programme: Annual Outcomes Report 2024. Singapore: NEA.
• World Health Organization. (2024). Heat and Health: WHO Guidance on Heat-Health Action Plans, 2nd Edition. Geneva: WHO.
• National Audit Office. (2024). Climate Adaptation and Public Health: Are We Prepared? London: NAO.