Photo: Gianluca Di natale/Flickr cc

How can we improve the risk assessment of PAHs, a group of chemicals known to be potentially hazardous to human health? In a recently defended doctoral thesis, Hwanmi Lim at the Department of Environmental Science and Analytical Chemistry (ACES) presents new methods to obtain more accurate data on PAH exposure as well as the possibilities of using these data in risk assessment research.

Polycyclic aromatic hydrocarbons, PAHs, are a group of chemicals formed during several types of combustion processes involving organic matter such as fossil fuel burning, smoking, wood fires and grilling. Some of the chemicals that occur can cause cancer and due to the risks associated with human exposure to PAHs, there are now EU regulations regarding concentrations in ambient air and limit values have been introduced.

Hwanmi Lim. Photo: Annika Hallman

“Based on this, measurement data with good quality are required and thus the used analytical methods need careful validation, which was one of the main objectives of this doctoral dissertation”, says Hwanmi Lim.

A challenge in PAH measurements is the broad diversity of chemical and physical properties within this class of compounds, and another common problem is the large number of chemical substances in for example the air in a city which can interfere in the analysis.

“In this thesis, the developed analytical systems utilize various techniques such as multidimensional chromatography to solve the interference problem. In addition, automation for PAH enrichment and clean-up, coupled online to the separation and detection, streamlines the sample analysis and minimises sample loss”, says Hwanmi Lim.

Furthermore, by using two-dimensional chromatography in combination with mass-selective detection, both selectivity and detectability are improved, resulting in increased accuracy and precision for the quantitative analysis.

As some of the PAH compounds are known to be potentially hazardous to human health her doctoral thesis presents two methods in order to improve the risk assessment of PAH.

“The first method is useful as a tool for studying biological effects of PAH mixtures by providing samples with and without the PAH compound benzo[a]pyrene, classified as a human carcinogen by the International Agency for Research on Cancer (IARC). With the second method, the compound benz[j]aceanthrylene was accurately measured in airborne particles and the associated risk of lung cancer could then be estimated”, says Hwanmi Lim.

What do you hope your thesis can contribute to?

“Providing more accurate data of environmental pollutants can help the regulatory body if there is a need of revising the current limit value. Also, an appropriate risk assessment can be achieved by a reliable measurement data, which this thesis work was aimed at, says Hwanmi Lim.

Her work has been part of a collaboration with Karolinska Institutet and funded by Stockholm University and the Swedish Research Council Formas.


Hwanmi Lims thesis “Automation, hyphenation and multidimensional chromatography for PAH analysis: Analytical techniques to simplify sample complexity” can be read here.

Text: Hwanmi Lim and Annika Hallman

Contact information

Visiting addresses:

Geovetenskapens Hus,
Svante Arrhenius väg 8, Stockholm

Arrheniuslaboratoriet, Svante Arrhenius väg 16, Stockholm (Unit for Toxicological Chemistry)

Mailing address:
Department of Environmental Science
Stockholm University
106 91 Stockholm

Press enquiries should be directed to:

Stella Papadopoulou
Science Communicator
Phone +46 (0)8 674 70 11