Adjustment Criteria for Air Quality Standards by Altitudes: A Scoping Review with Regulatory Overview

Air quality standards (AQS) are key regulatory tools to protect public health by setting pollutant thresholds. However, most are based on sea-level data. High-altitude (HA) environments differ in atmospheric conditions, influencing pollutant behavior and human vulnerability. These conditions have prompted proposals for altitude-specific AQS adjustments. This systematic review identifies models and criteria supporting such adapta-tions and examines regulatory air quality frameworks in countries with substantial populations living in HA. PRISMA-P guidelines and a Population/Concept/Context (PCC) framework were used to define the search terms: Population (Air Quality Standards), Concept (Air Pollutants), and Context (Altitude). Relevant literature was retrieved from MEDLINE, SCOPUS, Web of Science, and Gale OneFile: Environmental Studies and Poli-cy. A total of 2,093 articles were identified after duplicate removal. Following title and ab-stract screening, 2,081 papers were excluded, leaving 12 for full-text evaluation. Ultimately, six studies met the eligibility criteria. Three studies focused on adjustment models based on atmospheric conditions, such as temperature and pressure changes, while the other three examined human physiological responses, particularly the increased inhaled air volume. China, Peru, and Bolivia have the largest populations living above 3,500 m a.s.l., yet none of these countries have specific air quality regulations tailored to HA conditions. The review underscores the necessity for tailored AQS in HA environments.