Development and application of observable response indicators for design of an effective ozone and fine-particle pollution control strategy in China

oleh: J. Xing, J. Xing, D. Ding, D. Ding, S. Wang, S. Wang, Z. Dong, Z. Dong, J. T. Kelly, C. Jang, Y. Zhu, J. Hao, J. Hao

Format: Article
Diterbitkan: Copernicus Publications 2019-11-01

Deskripsi

<p>Designing effective control policies requires efficient quantification of the nonlinear response of air pollution to emissions. However, neither the current observable indicators nor the current indicators based on response surface modeling (RSM) can fulfill this requirement. Therefore, this study developed new observable RSM-based indicators and applied them to ambient fine-particle (PM<span class="inline-formula"><sub>2.5</sub>)</span> and ozone (<span class="inline-formula">O<sub>3</sub></span>) pollution control in China. The performance of these observable indicators in predicting <span class="inline-formula">O<sub>3</sub></span> and PM<span class="inline-formula"><sub>2.5</sub></span> chemistry was compared with that of the current RSM-based indicators. <span class="inline-formula">H<sub>2</sub>O<sub>2</sub></span>&thinsp;<span class="inline-formula">×</span>&thinsp;<span class="inline-formula">HCHO∕NO<sub>2</sub></span> and total ammonia ratio, which exhibited the best performance among indicators, were proposed as new observable <span class="inline-formula">O<sub>3</sub></span> and PM<span class="inline-formula"><sub>2.5</sub></span> chemistry indicators, respectively. Strong correlations between RSM-based and traditional observable indicators suggested that a combination of ambient concentrations of certain chemical species can serve as an indicator to approximately quantify the response of <span class="inline-formula">O<sub>3</sub></span> and PM<span class="inline-formula"><sub>2.5</sub></span> to changes in precursor emissions. The observable RSM-based indicator for <span class="inline-formula">O<sub>3</sub></span> (observable peak ratio) effectively captured the strong <span class="inline-formula">NO<sub><i>x</i></sub></span>-saturated regime in January and the <span class="inline-formula">NO<sub><i>x</i></sub></span>-limited regime in July, as well as the strong <span class="inline-formula">NO<sub><i>x</i></sub></span>-saturated regime in northern and eastern China and their key regions, including the Yangtze River Delta and Pearl River Delta. The observable RSM-based indicator for PM<span class="inline-formula"><sub>2.5</sub></span> (observable flex ratio) also captured strong <span class="inline-formula">NH<sub>3</sub></span>-poor conditions in January and <span class="inline-formula">NH<sub>3</sub></span>-rich conditions in April and July, as well as <span class="inline-formula">NH<sub>3</sub></span>-rich conditions in northern and eastern China and the Sichuan Basin. Moreover, analysis of these newly developed observable response indicators suggested that the simultaneous control of <span class="inline-formula">NH<sub>3</sub></span> and <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions produces greater benefits in provinces with higher PM<span class="inline-formula"><sub>2.5</sub></span> exposure by up to 1.2&thinsp;<span class="inline-formula">µ</span>g&thinsp;m<span class="inline-formula"><sup>−3</sup></span> PM<span class="inline-formula"><sub>2.5</sub></span> per 10&thinsp;% <span class="inline-formula">NH<sub>3</sub></span> reduction compared with <span class="inline-formula">NO<sub><i>x</i></sub></span> control only. Control of volatile organic compound (VOC) emissions by as much as 40&thinsp;% of <span class="inline-formula">NO<sub><i>x</i></sub></span> controls is necessary to obtain the co-benefits of reducing both <span class="inline-formula">O<sub>3</sub></span> and PM<span class="inline-formula"><sub>2.5</sub></span> exposure at the national level when controlling <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions. However, the VOC-to-<span class="inline-formula">NO<sub><i>x</i></sub></span> ratio required to maintain benefits varies significantly from 0 to 1.2 in different provinces, suggesting that a more localized control strategy should be designed for each province.</p>