Oops… our VOC calculation was 1000x wrong

On December 17, we reported our finding that the Volatile Organic Compound (VOC) pollution from Hong Kong’s 3 billion cigarettes amounted to around 11,477 tonnes, a quite shocking amount which should be included in the city’s emissions inventory.

Unfortunately, we were quite wrong. We based our calculations on a paper from Environmental Science Technology which contained a mistake (seemingly a typo) in its abstract: the paper revealed the VOCs per cigarette as 3,644 mg/cigarette. But on checking more carefully, our friends at the Environmental Protection Department revealed this to be a mistake: in the paper itself, the number is listed as 3,644μg/cigarette – ie, microgrammes not milligrammes – which means instead of 11,477 tonnes per year, our figure should be 11.477 tonnes per year.

The EPD uses the European Energy Agency figures for VOC from cigarettes to confirm the order of magnitude; according to EEA emissions factors, each cigarette produces 4,840μg VOCs, which yields a VOC pollution of around 15 tonnes for 3.1 billion cigarettes.

Apologies to our readers for this mistake.

On the bright side, on re-checking and confirming the EPD’s discovery, we did discover the excellent Norwegian emissions inventory which goes into incredible depth for thousands of emissions sources and is certainly a direction we would like to see Hong Kong move. Our ~15 tonnes of VOCs from cigarettes may not be as newsworthy as 15,000 tonnes, but it’s not nothing (and it’s largely on street level in the faces of pedestrians). Full transparency on emissions reporting helps environmental campaigners, and we would promote the Norwegian study as a gold standard in this regard.


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  1. Why is the smoke from 3 billion cigarettes not included in our emissions inventory? – Blue Skies China

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