Ambient Ozone Control in a Photochemically Active Region: Short-Term Despiking or Long-Term Attainment?

Abstract

China has made significant progress decreasing the ambient concentrations of most air pollutants, but ozone (O3) is an exception. O3 mixing ratios during pollution episodes are far higher than the national standard in the Pearl River Delta (PRD), thus greater evidence-based control efforts are needed for O3 attainment. By using a validated O3 modeling system and the latest regional emission inventory, this study illustrates that control strategies for short-term O3 despiking and long-term attainment in the PRD may be contradictory. VOC-focused controls are more efficient for O3 despiking in urban and industrial areas, but significant NOx emission reductions and a subsequent transition to a NOx-limited regime are required for O3 attainment. By tracking O3 changes along the entire path toward long-term attainment, this study recommends to put a greater focus on NOx emission controls region-wide. Parallel VOC reductions around the Nansha port are necessary in summertime and should be extended to the urban and industrial areas in fall with a flexibility to be strengthened on days forecasted to have elevated O3. Contingent VOC-focused controls on top of regular NOx-focused controls would lay the groundwork for striking a balance between short-term despiking and long-term attainment of O3 concentrations in the PRD.

Modeling C1–C4 Alkyl Nitrate Photochemistry and Their Impacts on O3 Production in Urban and Suburban Environments of Hong Kong

“…Based on Figure , the NO x ‐limited and VOC‐limited regimes in RONO 2 formation were identified. Briefly, the points with the lowest TVOCs on each isopleth line were linked in a straight line (dividing line), and RONO 2 formation in the area below and above the line was limited by VOCs and NO x , respectively (Ou et al, ). Linear regressions were carried out for these dividing lines and a TVOC/NO x ratio of approximately 10.0 ± 0.4 ppbv/ppbv ( R 2 = 0.97) was obtained for the simulated production of C 2 –C 4 RONO 2 based on the air pollutant profiles at TMS.…”

“…Based on Figure 4, the NO x -limited and VOC-limited regimes in RONO 2 formation were identified. Briefly, the points with the lowest TVOCs on each isopleth line were linked in a straight line (dividing line), and RONO 2 formation in the area below and above the line was limited by VOCs and NO x , respectively (Ou et al, 2016). Linear regressions were carried out for these dividing Figure 4.…”

Impact of anthropogenic emissions on biogenic secondary organic aerosol: observation in the Pearl River Delta, southern China

“…SOA I formation is highly affected by NO x . Under low-NO x or NO x -free conditions, isoprene is oxidized by the OH and HO 2 radicals via the HO 2 channel which generates a hydroxy hydroperoxide (ISOPOOH) and then forms epoxydiols (IEPOX) (Paulot et al, 2009). Reactive uptake of IEPOX on acidic particles eventually produces 2-MTLs, C 5 -alkene triols, 3-MeTHF-3,4-diols, 2-MTLs-organosulfates, and oligomers (Lin et al, 2012).…”

The effect of cetane number and oxygen content in the performance and emissions characteristics of a diesel engine using biodiesel blends

“…Diesel exhaust is now classified as carcinogenic to humans (Benbrahim-Tallaa et al, 2012), with exposure linked to increased risk of lung cancer and cardiovascular diseases (Giles et al, 2012). Diesel exhaust emissions are considered the primary source of providing ground-level ozone (Innes, 1981), sick building syndrome (Hester and Harrison, 2009), acid rain (Mills and Elouali, 2015) and smog (Ou et al, 2016). The need to find alternative sources of fuel energies with the more desirable characteristics of petroleum-based fossil fuels can, therefore, not be overemphasised (Damodharan et al, 2018).…”