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Polycyclic aromatic hydrocarbons (PAHs) in the air
Barbora Nežiková

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Outline
•Polycyclic aromatic hydrocarbons (PAHs)
•Air
•Conclusion
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Polycyclic aromatic hydrocarbons (PAHs)
•Organic compounds with two or more fused aromatic rings
•Always in mixture, analysis only of few selected
–16 EPA priority
–+ other depending on the study
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PAHs
•Sources – Burning processes
–Anthropogenic – generally byproduct
–Natural – forest fires, volcanos
•Biggest jump in concentration in history
–Industrial Revolution
–More common use of cars
•Pseudo-persistent
–Destruction on sun, biodegradation, reaction with other compounds
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PAHs - Sources
•520 000 tones per year globally
•China, India and USA – biggest contributors

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PAHs - Sources


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PAHs
•Toxicity – carcinogenic and mutagenic
–Benzo[a]pyrene – 1 IARC
–Dibenzo[a,h]anthracene – 2A IARC
–Benz[a]anthracene  – 2B IARC
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Number
Meaning
1
Carcinogenic to humans
2A
Probably carcinogenic to humans
2B
Possibly carcinogenic to humans
3
Not classifiable
4
Probably not carcinogenic to humans

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Fate in the air
•Depending on properties of PAHs and meteorological factors
•Most important – partitioning between gaseous and particulate phase
–Defined by partitioning constant Kp

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Modelling of Kp
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•Different models, different approaches
–Single parameter
–Poly parameter

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Transformations
•Can transform
–NO2-PAHs, OH-PAHs, Oxy-PAHs,…
•Can be more toxic
•Less information about them
•Problems with methodology and lack of data

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Air
•Dynamic and homogenous matrix
•Sampling
–Active x passive
–Gaseous x particulate phase
–Indoor x outdoor
•Many different studies, lots of data
–Can we compare them?
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Concentration
•Strongly depending on locality and part of year
•Differences in gaseous and particulate phase
•Indoor
–Depending on smoking and cooking
–About dozens ng/m3
•Outdoor
–Background locality – about units ng/m3
–Urban areas – even hundreds ng/m3
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Legislation
•Not part of Stockholm convention
•Included in Convention on Long-range Transboundary Air Pollution
•Emission limit for B[a]P – 1 ng/m3

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Methodology
•Very traditional pollutants in traditional matrix
•Good analytical and sampling methods
–Careful about sampling artefacts!
–Problem with dibenz[a,h]anthracene and benzo[k]fluoranthen
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•No need for improvement

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Connection to human
•Biggest exposure of PAHs for humans is from food
•Important source from air - smoking
•Increased risk of cancer
–Mostly associated with PM2.5

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What now?
•Educate public about health hazards associated with PAHs •Do one uniform method so we can compare
and share data •Fill the gaps about toxicology and methodology of derivatives of PAHs

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What then?
•Impossible to ban (natural sources) → try to lower anthropogenic sources
–Improve our technologies and vehicles
•Continue to monitor PAHs in the air
–But be careful about data and how they were „created“!
–Widen monitoring data to humans
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•Thank you for your attention!
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•Any questions?