Ammonium Nitrate Chemistry

Fake Plastic Tree Refuses to Die

Just like that cheap plastic Christmas tree that mum trots out every year, stories about the scientifically questionable CityTree refuse to die.  This press release masquerading as news has been rehashed and reprinted with little scientific analysis by Wired, Forbes, Dezeen, CNN - and - so -  many - others that it made me throw up in my mouth a little and I had to stop googling it.

As I wrote the other day, these CityTrees make almost impossible claims to purify air of nearly every pollutant, all the way from particulate matter down to carbon dioxide.  This last one is the most challenging to accept, as it has been reported that each fake plastic tree "has the air purifying power of 275 normal trees". That is a direct quote from once-respected newspaper The Independent. Yes, that The Independent.

It is claimed that each one of these devices removes 240,000 kg of carbon dioxide from the air every year, equivalent to a small forest.  This means, however, that about one tonne (or around 2000 lb) of solid material would need to be produced - and presumably removed from site and sequestered - Monday through Friday every single week.  And even at a modest carbon price each unit could sell millions of dollars a year in credits.  So, this CO2 claim almost certainly has to be false, yet none of the reports cited here call bullshit on it, or even question it.

Everyone would love for there to be a quick and easy solution to air pollution and climate change, but there is real damage that can come from supporting and encouraging misguided approaches.  Taxpayer money, particularly from cash-strapped local municipalities, can easily be diverted to greenwashing exercises with no real environmental benefits, while investment dollars are directed away from serious efforts.

Meanwhile, over at NBC News site MACH, there is a proper news article about a large scale outdoor air purifier which makes much more modest claims.  The story even features quotes from multiple experts with dissenting views!  In brief, a 200 foot tall tower has been built in the heavily polluted Chinese city of Xi'an, where it aims to remove one of the deadliest components of air pollution, PM2.5, from the surrounding skies.  Personally, I'm still skeptical about the feasibility of these devices, but at least this effort is focused on one specific problem and hasn't confined itself to first world cities.