Nationwide ground-level ozone measurements in China suggest serious risks to forests. (June 2018)

• Record Type: Journal Article
• Authors: Li, Pin; De Marco, Alessandra; Feng, Zhaozhong; Anav, Alessandro; Zhou, Daojing; Paoletti, Elena
• Is Part Of: Environmental pollution. Volume 237(2018)
• Page Start: 803
• Page End: 813
• Publication Date: 2018-06
• Subjects: Surface ozone -- Ozone-exposure metrics -- Risk assessment -- Forests -- China; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2017.11.002
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: We processed hourly ozone (O3 ) concentrations collected in 2015 and in 2016 by a network of 1497 stations across China, with the main aim of assessing the risk that present ambient O3 exposure is posing to Chinese forests. Our results indicate that the values of the metrics AOT40 (the accumulated hourly O3 concentrations above 40 ppb during daylight hours) recommended as European Union standard, and W126 (the sum of weighted hourly concentrations from 8:00 to 20:00) recommended as USA standard for forest protection, exceeded the critical levels (5 ppm h across 6 months for AOT40 and 7–21 ppm h over 3 months for W126) on average by 5.1 and 1.2 times, respectively. N100 showed on average 65 annual exceedances of 100 ppb as hourly value. The 12-h and 24-h averages showed a small difference, suggesting high concentrations also at night. Risk was higher for the northern temperate climate than for the southern tropical and sub-tropical climates, and overall for the northern regions than for the southern regions. Higher risk occurred in the non-urban areas than in the urban areas in northern, south-west and north-west China, whereas risk was higher at urban areas in eastern and southern China. The overall results of this first nationwide assessment suggest a significant risk for forests over the entire China and warrant for urgent measures for controlling O3 precursor emissions and establishing standards of protection. Graphical abstract: Image 1 Highlights: Ozone risk to forests was assessed by data from 1497 stations across China. Metrics for forest protection (AOT40 and W126) exceeded the critical levels. Risk was higher for northern temperate forests than for southern subtropical forests. The variation of risk depended on the geographical regions and climate zones. Abstract : Risk was higher for northern forests than for southern forests.