MPhil Thesis Presentation - Hidden Compound Burden: Real-Flight Trajectories Reveal Aviation Noise and Pollution Exposure in a Megacity Airspace

Airports load their surrounding communities with two co-located environmental hazards, aircraft noise and aviation-attributable air pollution, yet regulatory practice assesses and manages them as separate, single-stressor problems. Using Automatic Dependent Surveillance–Broadcast (ADS-B) telemetry, this thesis reconstructs four-dimensional flight trajectories for all commercial and cargo operations at Hong Kong International Airport over 2019–2025 and converts them into two spatially explicit exposure products: a receptor-level day–evening–night noise field and a vertically resolved, three-dimensional emission inventory. The emission inventory shows that the surface-relevant burden originates in the high-thrust take-off and climb phase, with about 69% of the column carbon dioxide released below 3 km, and it reproduces official regulatory totals while resolving structure that coarser global inventories blend away. A reduced-form, weather-type-stratified representative-day dispersion–chemistry model, paired with a surrogate response model, then reconstructs the daily aviation air-quality increment, whose reach is species-dependent: primary nitrogen dioxide decays within a few kilometres of the airport, while secondary ozone and nitrate fine particulate persist to roughly 30 km.

The noise and pollution fields are coupled through a copula that captures their upper-tail dependence. Three findings follow. First, aircraft-noise exposure is governed by flight-corridor geometry rather than by a city-wide socioeconomic gradient: its aggregate distribution is essentially neutral with respect to status, and the equity concern is localised in a few already-disadvantaged corridor communities. Beyond this, because the two exposures share a trajectory source, current single-stressor practice understates the probability of joint high exposure by about 3-fold at the 75th percentile and by up to 5-fold in the extreme upper tail; the dual-burden population is bracketed between roughly 100 residents under the primary nitrogen-dioxide metric and 600 under a total-oxidant upper bound. Most strikingly, and contrary to the canonical environmental-justice expectation, that dual-burden population is more affluent than the population exposed to high noise alone, because in a planned-housing megacity it is proximity to the flight path, not the housing market, that sorts residents into the joint high tail. The compound burden is strongly weather-modulated, with winter cold surges raising the dual-exposure population about 3-fold over summer stagnation, and the aviation nitrogen-dioxide increment is estimated to cause 48 (95% CI 24–95) attributable premature deaths per year, a figure consistent with independent airport-scale studies. A full-pipeline sensitivity analysis confirms that the compound under-count and the income reversal are structural rather than artefacts of modelling choices. Together these results establish that the compound environmental burden of aviation in a dense, constrained megacity airspace cannot be recovered by summing two single-hazard assessments, and that dependence-aware, receptor-based, weather-resolved evaluation is required to locate the population where a joint intervention would do the most good.