Publications·April 10, 2025
This policy brief distils the priority actions agreed by two open-ended RAPAP Working Groups—one on air-quality standards and one on monitoring & data—to accelerate clean-air progress across Asia-Pacific. It synthesizes the state of play (who has what standards, who monitors what, how open the data are) and sets out concrete regional recommendations on (i) harmonising National Ambient Air Quality Standards (NAAQS) with WHO guidelines, (ii) building robust monitoring systems (reference-grade, remote sensing, low-cost sensors, and fusion), (iii) ensuring fully open data, and (iv) cooperation & best-practice exchange. Health stakes are stark: WHO and State of Global Air estimates indicate millions of premature deaths annually, with the largest share in South-East Asia and the Western Pacific, and the burden likely rising without stronger controls.
Process & provenance. The brief consolidates inputs from Working Group sessions (Sept 2023, Mar 2024), underwent consultation before the 8th ESCAP Committee on Environment and Development (Oct 2024), and is part of ESCAP’s project to operationalize RAPAP adopted at CED7 (Dec 2022).
I. Raising and harmonising air-quality standards
WHO Air Quality Guidelines (2021) provide the evidence-based reference; any exceedance entails health risk, and Interim Targets (IT1–IT4) offer stepwise goals where guideline attainment is not yet feasible. Across the region, NAAQS coverage and stringency vary widely by pollutant, averaging time and legal framing, and many countries’ standards are well above WHO levels. The brief notes common reliance on secondary legislation (easier to update but sometimes weak on enforceability), and highlights the Republic of Korea as an example where robust law underpinned improvements.
Where countries stand on PM₂.₅ (annual):
IT3 (15 µg/m³): Japan, Republic of Korea, Singapore, Malaysia, Indonesia, Bangladesh, Pakistan.
IT2 (25 µg/m³): Mongolia, Viet Nam, Thailand, Sri Lanka.
IT1 (35 µg/m³): China (with proposals to tighten).
None at IT4 or guideline for annual/daily PM₂.₅ yet on the Asian continent.
Priorities include periodic reviews, adoption of WHO IT/Guideline values as legally binding NAAQS (starting with PM₁₀/PM₂.₅), and targeted technical cooperation for transboundary-challenged, lower-income subregions (e.g., Lower Mekong; Indo-Gangetic).
II. Building robust monitoring: reference-grade + EO + sensors + fusion
Why it matters. Monitoring enables standard-setting, compliance checks, evaluation of interventions, episode response, and public-health guidance. The brief positions a hybrid strategy:
Reference-grade stations (regulatory backbone): high accuracy/traceability but cost and O&M intensive.
Remote sensing (satellites + ground-based spectrometers/lidars): broad coverage, diurnal patterns; needs models and/or ground data to infer surface concentrations.
Low-cost sensors: expand spatial coverage and community engagement; require calibration/QA/QC; performance varies by pollutant and environment.
Data-fusion/ML products: merge satellites, CTMs and in-situ to deliver high-coverage, decision-grade fields, if rigorously validated.
Where the region is now. Monitoring density per million people varies from ~18.7 (ROK) and 14.5 (Japan) to ~1.0–1.3 in Lao PDR/Philippines/Viet Nam, and <0.2 in Sri Lanka/Bangladesh; China stands near 3.5 despite scale. Governments and programmes are also deploying low-cost networks (e.g., Cambodia’s 44 sensors; Indonesian pilots) and leveraging geostationary/LEO satellites (e.g., GEMS), with ESCAP and partners advancing capacity via the Pan-Asia Partnership for Geospatial Air Pollution Information. Recommended actions: harmonise methods and QA/QC; use reference-grade where feasible; supplement with sensors; invest in EO; and operationalise fusion models for coverage and innovation.
III. Make air-quality data fully open
Open data = better policy, science, and public protection. The brief adopts OpenAQ’s four criteria for “fully open” data: provide physical units (not just AQI), station geolocation, timely/near-real-time access, and programmatic or machine-readable formats. While many Asia-Pacific countries publish AQI in near real time, long-term, unit-based datasets remain scarce. Currently, only Australia, Japan, Kyrgyz Republic, New Zealand, and Republic of Korea meet all four open-data criteria. Data portals in China, India, Thailand, Türkiye lack programmatic access; Indonesia and Pakistan lack both coordinates and programmatic access. Recommendations: prioritise unit-based, station-resolved data, add APIs, flag sensor vs. reference data, and standardise open-data protocols alongside accessible dashboards and public communication.
IV. Cooperation & exchange of best practices
Cross-border pollution and shared airsheds demand regional collaboration. The brief calls for:
Network-to-network cooperation (ground + remote sensing) and harmonised QA/QC (build on WHO/WMO/UNEP/OpenAQ guidance).
Continuous knowledge exchange (webinars, workshops, working groups) and documentation of financing models, public/political buy-in, and policies that protect poor and vulnerable groups.
Compilation and sharing of national commitments, targets, success stories, and multi-sector policy outcomes (energy, transport, agriculture, industry) to make standards and management more comparable and effective across the region.
Five takeaway recommendations (action-oriented)
Legally bind and tighten NAAQS toward WHO AQGs, starting with PM₂.₅/PM₁₀, and schedule periodic reviews.
Stand up a hybrid monitoring fabric: expand reference-grade stations, integrate GEMS/other EO, scale calibrated low-cost sensors, and publish fusion products with uncertainty.
Adopt “fully open” data practices (units, coordinates, timeliness, APIs); publish long-term datasets for exposure and burden assessments.
Invest in people, O&M and QA/QC to move from research pilots to operational, decision-ready services (alerts, compliance targeting, evaluation).
Deepen regional cooperation on airsheds/transboundary haze, and systematically share best practices, financing approaches, and outcomes.
Key words
Air quality standards; WHO AQGs & Interim Targets; NAAQS harmonization; reference-grade monitoring; remote sensing (GEMS); low-cost sensors; data fusion / ML; fully open data (units/coords/APIs/real-time); QA/QC; airsheds & transboundary haze; cooperation & best-practice exchange; vulnerable populations.