Heavy metal from cars: Statistical analyses of spectra

Skip to Navigation


  • Published: Mar 15, 2017
  • Author: David Bradley
  • Channels: Chemometrics & Informatics
thumbnail image: Heavy metal from cars: Statistical analyses of spectra

PCA on city dust

Multivariate statistical techniques, principal component analysis (PCA), and hierarchical cluster analysis have been used to process data on metal pollutants in a densely populated city based on atomic absorption spectra.

Multivariate statistical techniques, principal component analysis (PCA), and hierarchical cluster analysis have been used to process data on metal pollutants in a densely populated city based on atomic absorption spectra.

Chemist Mohammad Ebqa'ai of Umm Al-Qura University in Saudi Arabia and Bashar Ibrahim of the Friedrich-Schiller-University in Jena, Germany, have analysed almost 100 street dust samples from Jeddah, the second largest city in the Gulf Cooperation Council with a population of more than 3.5 million people, and a very large number of vehicles.

Jeddah is located on the west Red Sea coast of Saudi Arabia, it is hot and humid in the summer (usually around 40 degrees Celsius) although a little cooler in the winter (30 degrees Celsius) and while its permanent population is 3.6 million it adds at least another 2 million people annually and temporarily during the pilgrimage season with Mecca just 70 kilometres inland. Air and sea traffic to and from Jeddah is heavy, exacerbated by the fact that the city is connected to the most important road in Saudi Arabia , the Highway, which crosses the entire Arabian Desert to Dammam, the capital of the Eastern Province of the Kingdom. It is estimated that there are 3 million cars in Jeddah at any given time.

Anaemia and asthma

The team collected samples at different times of year from the city's six major roads as well as the Jeddah Beach and digested for AAS using a modified Leeds Public Analyst method. The team extracted cadmium, copper, iron, lead, manganese, and zinc from the resulting ash using methyl isobutyl ketone as a solvent extractant.

" In order to study the pollution and health risk from these heavy metals as well as estimating their effect on the environment, pollution indices, integrated pollution index, enrichment factor, daily dose average, hazard quotient, and hazard index were all analysed," the team reports in the journal Environmental Geochemistry and Health.

Most of the roads analysed had high levels of pollution, with the exception of King Fahad Road. The team's PCA showed high levels of Zn, Fe, and Cd in Al Kurnish road, for instance, while these elements were also detected repeatedly on King Abdulaziz and Al Madina roads. Lead and zinc levels were high for all of Jeddah's major roads. The study is the first step towards finding a correlation between heavy metal pollutants in this busy city of the Middle East and current health problems there, including anaemia and asthma.

Baseline health risk

Toxic heavy metals are widespread pollutants, they are generally not metabolised and so accumulate in the environment and rattle their way up the food chain. It is also common that city dwellers will absorb inordinate amounts of these elements through the simple act of breathing. The effects of fine dusts containing heavy metals have been studied in children widely and all kinds of health problems are known to arise through inhalation, oral ingestion and contact with the skin. Although they are not metabolised they do interact strongly with biochemical processes in the body, displacing the natural metallic elements in enzymes, bone and tissue, for instance, and disrupting critical systems and structures. Long-term exposure is likely to come at a high price in terms of childhood development and chronic health risks. Restrictions in the likes of lead in vehicle fuel are already in place, but there remain many sources of this toxic metal and others that existence of which ought to be addressed.

The team found no seasonal variations in heavy metal levels through the course of a year. The mean heavy metal concentrations were in descending order of Fe > Zn > Mn > Cu > Pb > Cd, the researchers report. In comparing their data to background concentrations (from natural samples) they come to the conclusion that levels of heavy metals in Jeddah city are influenced by human activity. Critically, the team says, "Taken together, the pollution assessment demonstrated that the heavy metal concentrations of zinc and lead levels from road dust in Jeddah could adversely impact upon health of children and adults and must be dealt with as soon as possible."

"Our next step is to study the indoor environment and air pollution in Jeddah and their impact on specific human diseases in Jeddah," Ibrahim told SpectroscopyNOW. "We believe for a better understanding, we need to study the six major cities of the Saudi Red Sea coast." Ibrahim points out that the team has very limited funds currently from the German side alone, which hinders their plans for more research.

Related Links

Environ Geochem Health 2017, online: "Application of multivariate statistical analysis in the pollution and health risk of traffic-related heavy metals"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

Follow us on Twitter!

Social Links

Share This Links

Bookmark and Share


Suppliers Selection
Societies Selection

Banner Ad

Click here to see
all job opportunities

Most Viewed

Copyright Information

Interested in separation science? Visit our sister site separationsNOW.com

Copyright © 2018 John Wiley & Sons, Inc. All Rights Reserved