Methodology¶
Research Approach¶
Port Health Watch follows a "follow the money" methodology — tracing financial flows through public health systems to reveal the hidden costs that port-adjacent communities bear from shipping emissions. All analysis uses publicly available, primary-source data and peer-reviewed quantification frameworks.
Data Sources¶
| Source | Agency / Publisher | Data Used |
|---|---|---|
| Global Port Emissions Inventory Tool (goPEIT) | ICCT | Vessel-level emissions by port, vessel class, and operating mode |
| National Emissions Inventory | U.S. EPA | Port-area emissions from all mobile and stationary sources |
| Benefits Mapping and Analysis Program (BenMAP) | U.S. EPA | Health impact assessment framework and concentration-response functions |
| Intervention Model for Air Pollution (InMAP) | Published open-source model | Reduced-complexity dispersion modeling for PM2.5 concentration changes |
| American Community Survey | U.S. Census Bureau | Population demographics, income, poverty status by census tract |
| Social Vulnerability Index (SVI) | CDC/ATSDR | Community vulnerability to health stressors |
| EJScreen | U.S. EPA | Environmental justice screening indicators |
| Air Quality System (AQS) | U.S. EPA | Monitored ambient air quality data from regulatory monitors |
| State/local health surveillance | State DOH / local health departments | Baseline rates for mortality, hospitalizations, ED visits |
| At-Berth Regulation compliance data | CARB | California-specific vessel compliance and technology performance |
Health Impact Quantification¶
Our health impact estimates follow the same concentration-response methodology used by the EPA in its Regulatory Impact Analyses for the Clean Air Act and National Ambient Air Quality Standards (NAAQS):
Step 1 — Emissions Inventory: Quantify at-berth emissions by pollutant (PM2.5, NOx, SOx, CO2) using ICCT vessel activity data and EPA emission factors.
Step 2 — Dispersion Modeling: Model the change in ambient PM2.5 concentration in surrounding communities using InMAP or equivalent reduced-complexity model. Output is a grid of concentration changes at census tract resolution.
Step 3 — Health Impact Calculation: Apply peer-reviewed concentration-response functions to translate concentration changes into health outcomes:
$$\Delta I = \beta \times \Delta X \times P \times I_0$$
Where ΔI is the change in health events, β is the effect coefficient from epidemiological studies, ΔX is the change in pollutant concentration, P is the exposed population, and I₀ is the baseline rate of the health outcome.
Step 4 — Monetization: Convert health outcomes to economic values using EPA's Value of Statistical Life ($11.8M, 2024-adjusted) for mortality and standard willingness-to-pay estimates for morbidity endpoints.
Key Concentration-Response Functions¶
| Health Endpoint | Source Study | Effect Estimate |
|---|---|---|
| All-cause mortality (adults 30+) | Krewski et al. 2009 (ACS CPS-II) | 6% increase per 10 μg/m³ PM2.5 |
| All-cause mortality (extended) | Lepeule et al. 2012 | 14% increase per 10 μg/m³ PM2.5 |
| Cardiovascular hospitalizations | Zanobetti et al. 2009 | Effect estimates from Medicare cohort |
| Respiratory hospitalizations | Zanobetti et al. 2009 | Effect estimates from Medicare cohort |
| Asthma ED visits | Mar et al. 2010 | Effect estimates from multi-city study |
Conservatism & Uncertainty¶
All estimates on this site are intentionally conservative:
- We report ranges reflecting uncertainty in dispersion modeling and exposure assumptions
- We exclude secondary PM2.5 formation from NOx and SOx (which would increase totals)
- We use the lower-bound Krewski et al. function rather than the higher Lepeule et al. estimate as our primary reference
- We do not include chronic morbidity endpoints (cancer incidence, neurological effects) where evidence is strong but quantification is less standardized
Citation Standards¶
Every data point on this site includes a primary source citation with direct link to the original publication. All data sources and assumptions are fully documented to ensure reproducibility and defensibility in regulatory, legal, and legislative settings.
Corrections Policy¶
If you identify an error in our data or analysis, contact us at research@porthealthwatch.org. We will promptly investigate and correct any verified errors with a transparent correction notice.