RESUMEN
Photochemical regime for ozone (O3) formation is complicated in the sense that reducing emission of nitrogen oxides (NOx) may increase O3 concentration. The lockdown due to COVID-19 pandemic affords a unique opportunity to use real observations to explore the O3 formation regime and the effectiveness of NOx emission control strategies. In this study, observations from ground networks during the lockdowns were used to assess spatial disparity of the Ratio of Ozone Formation (ROF) for nitrogen dioxide (NO2) reduction in the Greater Bay Area (GBA) of China. The health risk model from Air Quality Health Index (AQHI) system in Hong Kong was adopted to evaluate the risk tradeoffs between NO2 and O3. Results show that the levels of O3 increase and NO2 reduction were comparable due to high ROF values in urban areas of central GBA. The ozone reactivity to NO2 reduction gradually declined outwards from central GBA. Despite the O3 increases, the NOx emission controls reduced the Integrated Health Risk (IHR) of NO2 and O3 in most regions of the GBA. When risk coefficients from the AQHI in Canada or the global review were adopted in the risk analyses, the results are extremely encouraging because the controls of NOx emission reduced the IHR of NO2 and O3 almost everywhere in the GBA. Our results underscore the importance of using a risk-based method to assess the effectiveness of emission control measures and the overall health benefit from NOx emission controls in the GBA.
RESUMEN
PURPOSE: This study was to evaluate the associations of dietary intake of total and specific phytosterols and risk of esophageal squamous cell carcinoma (ESCC) and to explore their joint effects with PLCE1 rs2274223 polymorphisms. METHODS: A population-based case-control study was conducted in a Chinese rural population and 856 eligible incident ESCC cases and 856 controls were included. A validated food frequency questionnaire was used to collect dietary consumption and PLCE1 rs2274223 polymorphisms were genotyped. Unadjusted and adjusted odds ratios (ORs) with 95% confidence interval (CI) were assessed via logistic regression model. RESULTS: When comparing the highest with lowest intake quartiles, ß-sitosterol, campesterol, stigmasterol, ß-sitostanol, campestanol, and total phytosterols were all associated with a decreased risk of ESCC, with adjusted ORs being 0.32 (95% CI 0.20-0.48), 0.18 (95% CI 0.11-0.27), 0.45 (95% CI 0.29-0.70), 0.13 (95% CI 0.08-0.20), 0.14 (95% CI 0.09-0.22) and 0.28 (95% CI 0.18-0.43), respectively. An exposure-response relationship was also observed for both total and five specific phytosterols (all P for trend < 0.001). In comparison to rs2274223 AA genotype, both GA genotype (OR: 1.47, 95% CI 1.16-1.85) and GG genotype (OR: 2.13, 95% CI 1.20-3.84) were associated with an increased risk of ESCC. However, no interaction was observed between total/specific phytosterols intake and rs2274223 polymorphisms. CONCLUSION: Higher dietary intake of total and five specific phytosterols was associated with a lower risk of ESCC, and the risk of ESCC increased with the increment of rs2274223 G allele. The negative association between phytosterols and ESCC risk was not modified by rs2274223 polymorphisms. Foods or supplements rich in phytosterols are a promising source for chemoprevention of ESCC, and still, clinical trials will be required in any specific case.