The Guangdong-Hong Kong-Macao Pearl River Delta recorded prominent air quality improvements in 2025, with concentrations of five major air pollutants maintaining a sustained downward trend over a twenty-year tracking period, according to a report released on Friday.
Two Decades of Declining Emissions Across the Delta
Jointly released by Guangdong province and the Hong Kong and Macao special administrative regions, the report shows annual average concentrations for sulphur dioxide, nitrogen dioxide, carbon monoxide, respirable suspended particulates, and fine suspended particulates declined by between 23 percent and 86 percent compared with two decades ago, chinadailyasia.com reported.
The most notable improvement appeared in sulphur dioxide. Its annual average concentration fell 86 percent, dropping from 44 micrograms per cubic meter in 2006 down to 6 micrograms per cubic meter in 2025.
Fine suspended particulates followed a similar downward trajectory. The annual average concentration of PM2.5 dropped 34 percent from 29 micrograms per cubic meter in 2015 to 19 micrograms per cubic meter in 2025, reaching a leading level nationwide.
Targeted Clean-Air Measures Drive Regional Results
Meanwhile, annual concentrations of nitrogen dioxide and respirable suspended particulates each declined by an average of 48 percent over their respective tracking periods. Carbon monoxide fell by 23 percent.
Governments across Guangdong and the two special administrative regions introduced a range of clean-air policies to achieve these metrics. Authorities prioritized the popularization of electric vehicles, managed volatile organic compounds, and oversaw the systematic phasing out of high-pollution vehicles.
Monitoring these improvements relies on a unified regional infrastructure. The Guangdong-Hong Kong-Macao Pearl River Delta Regional Air Quality Monitoring Network comprises 23 air monitoring stations distributed across Guangdong, Hong Kong, and Macao. Environmental protection authorities in the three jurisdictions coordinate the management and operation of these stations, releasing quarterly and annual monitoring results to the public.
| Pollutant | Baseline Year | Baseline Concentration | 2025 Concentration | Overall Change |
|---|---|---|---|---|
| Sulphur Dioxide (SO2) | 2006 | 44 μg/m³ | 6 μg/m³ | -86% |
| Fine Suspended Particulates (PM2.5) | 2015 | 29 μg/m³ | 19 μg/m³ | -34% |
| Carbon Monoxide (CO) | Tracking Start | – | – | -23% |
