Air quality in Yanbu, Saudi Arabia

ABSTRACT

Yanbu, on the Red Sea, is an affluent Saudi Arabian industrial city of modest size. Substantial effort has been spent to balance environmental quality, especially air pollution, and industrial development. We have analyzed six years of observations of criteria pollutants O₃, SO₂, particles (PM_2.5 and PM₁₀) and the known ozone precursors—volatile organic compounds (VOCs) and nitrogen oxides (NO_x). The results suggest frequent VOC-limited conditions in which ozone concentrations increase with decreasing NO_x and with increasing VOCs when NO_x is plentiful. For the remaining circumstances ozone has a complex non-linear relationship with the VOCs. The interactions between these factors at Yanbu cause measurable impacts on air pollution including the weekend effect in which ozone concentrations stay the same or even increase despite significantly lower emissions of the precursors on the weekends. Air pollution was lower during the Eids (al-Fitr and al-Adha), Ramadan and the Hajj periods. During Ramadan, there were substantial night time emissions as the cycle everyday living is almost reversed between night and day. The exceedances of air pollution standards were evaluated using criteria from the U.S. Environmental Protection Agency (EPA), World Health Organization (WHO), the Saudi Presidency of Meteorology and Environment (PME) and the Royal Commission Environmental Regulations (RCER). The latter are stricter standards set just for Yanbu and Jubail. For the fine particles (PM_2.5), an analysis of the winds showed a major impact from desert dust. This effect had to be taken into account but still left many occasions when standards were exceeded. Fewer exceedances were found for SO₂, and fewer still for ozone. The paper presents a comprehensive view of air quality at this isolated desert urban environment.

Implications: Frequent VOC-limited conditions are found at Yanbu in Saudi Arabia that increase ozone pollution if NO_x is are reduced. In this desert environment, increased nightlife produces the highest levels of VOCs and NO_x at night rather than the day. The effects increase during Ramadan. Fine particles peak twice a day—the morning peak is caused by traffic and increases with decreasing wind, potentially representing health concerns, but the larger afternoon peak is caused by the wind, and it increases with increasing wind speeds. These features suggest that exposure to pollutants must be redefined for such an environment.

Additional information

Funding

Financial support for this project was provided by King Abdulaziz University under grant no. 4-10-1432/HiCi.

Notes on contributors

M.A.K. Khalil

M. Aslam K. Khalil is a professor in the Department of Physics at Portland State University in Portland, OR.

Christopher L. Butenhoff

Christopher L. Butenhoff is an assistant professor in the Department of Physics at Portland State University in Portland, OR.

William C. Porter

William C. Porter is a research associate in the Department of Civil and Engineering at Massachusetts Institute of Technology, in Cambridge, MA.

Mansour Almazroui

Mansour Almazroui is the director of the Center of Excellence for Climate Change Research at King AbdulAziz University, in Jeddah, Saudi Arabia.

Abdulrahman Alkhalaf

Abdulrahman Alkhalaf is a professor of meteorology in the Faculty of Meteorology, Environment and Arid Land Agriculture at King AbdulAziz University, in Jeddah, Saudi Arabia.

Mohammed Saleh Al-Sahafi

Mohammed Saleh Al-Sahafi is Director General of Environmental Standards and National Ozone Coordinator at the Presidency of Meteorology and Environment in Saudi Arabia.