Quantification of volatile organic compounds in ten cities across three continents

Volatile organic compounds (VOCs) are emitted from both biogenic and anthropogenic sources. Biogenic compounds dominate VOCs emissions worldwide while the anthropogenic VOCs prevail in urban areas. Apart from undesired and direct human health effects, VOCs can affect the physical-chemical behaviour of the atmosphere in several ways. In addition to influencing local, regional and even global photochemistry, some of these compounds have a potential impact on climate (e.g. due to their ability to form aerosol particles). Despite these facts, few studies have focused on urban environments of developing countries where VOCs levels are expected to be high because of rapid industrialization and lenient regulations. People spend up to 80-90% of their time indoors (houses, offices, bars etc.) and a significant amount of time (5%) in traffic while commuting to and from work. However, air quality (e.g. exposure assessment) concerning a diversity of airborne VOCs for those micro-environments are hardly documented, even in the developed world. Given these considerations, quantitative data on VOCs levels in urban environments are of crucial importance in order to (i) enable comparison of pollution levels and exposure, and (ii) estimate their undesired effects (in particular, ozone formation potential and cancer risk assessment). In this thesis, VOCs have been measured in ten cities across five countries (i.e. Belgium, Vietnam, the Philippines, Bangladesh, and Ethiopia) in Europe, Asia, and Africa. All air sampling has been done in an active way using sorbent tubes filled with Tenax TA. The analysis has been excecuted by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) using internal standard calibration. The quantification resulted in a unique dataset of concentration levels of up to 84 VOCs in 450 samples from urban air regions or micro-environments where hardly data on VOCs exist today. This dataset has been used to make a first estimation of ozone formation potential and cancer risk via inhalation.

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