Air Quality Changes under the Influence of Cut-Off Lows and Omega Blocking Patterns and Associated Health Risks in a Coastal Mediterranean Region: Case of Bizerte, Northern Tunisia

Abstract

The study of the daily and diurnal variability of NO, NO2, surface O3 and PM10 was carried out in urban Bizerte (Northern Tunisia), from January to March, 2013. The main results showed three distinct periods depending on multi-scale sources and meteorology. The first period, (≈20% of total cases) influenced by moderately stable conditions, was characterized by a slight excess of NO due to traffic emissions. The second period, (≈ 60% of total cases) associated with moderately unstable conditions, was devoid of any significant impact of sources. The third period, (≈ 20% of total cases) distinguished by noteworthy excess of O₃ and PM10, was attributed to a marked effect of succeeding Cut-off lows and Omega blocking patterns. Under these conditions, the scatter plots of NO, NO₂, and O₃ versus NOx for daytime and nighttime showed good polynomial fit curves with high R² values for NO and NO₂ only. Under both moderately unstable and stable conditions, significant negative correlation coefficients between O₃ and NOx were found to be 0.53 (p < 0.05) and 0.50 (p < 0.05) for daytime and nighttime, respectively. Under Cut-off lows and Omega, an absence of any significant correlations between O₃ and NOx was noticed. Under Cut-off lows, the good linear regression fits between OX (=O₃ + NO₂) and NOx illustrated high NOx independent contributions, possibly attributed to the biogenic VOCs effect. The investigation of the air quality index (AQI) for NO₂, PM10 and O₃ (running 8-h mean) highlighted the significant effect of both O₃ and PM10 only under Cut-off lows and Omega which were retraced by poor to very poor air quality categories.

Keywords:

• Bizerte
• pollutants
• cut-off lows
• omega blocking patterns
• statistical tools
• health risks

Acknowledgments

The authors would like to thank Mr. Abdelmajid Dammak, English teacher and proofreader at the University of Sfax, for the careful editing and proofreading of this paper.

Authors’ Contributions

Fatma Sellami processed the data using descriptive and analytical approaches and wrote the manuscript, Rim Dammak helped in statistical data processing and was involved in results evaluation, Chafai Azri conceived the idea, performed the statistical analyses and improved the manuscript content. All authors read and approved the final version of the manuscript.

Disclosure Statement

The authors declare that they have no conflict of interest.

Data Availability Statement

All the data used in the present study are freely available to all through proper request, if needed by anyone for further research.