Air-filtering bus to launch across six regions in the UK | Hacker News Reader

Air-filtering bus to launch across six regions in the UK

theguardian.com

9 pointssefrost9 comments

"the bus removed approximately 65g of pollutants from the air and cleaned 3.2 million cubic metres of the city’s air."

This sounded surprisingly low to me, at 20µg/m³ removed, so I went looking for more info. It seems correct:

"Typical urban atmospheric loadings of PM range from tens to hundreds of µg m⁻³ for PM10. For a city such as London, a mean mass concentration for PM10 of the order of 30 µg m⁻³ might be observed; considering the area of Greater London (ca. 400 km² ) and assuming a 1 km boundary layer height, this equates to around 12 tonnes of material suspended above the city." -- https://www.rsc.org/images/environmental-brief-no-4-2014_tcm...

Comparison of PM10 for highly polluted European cities here: https://www.london.gov.uk/sites/default/files/comparison_of_...

"Go-Ahead’s estimates show that the expanded fleet could remove as much as 1.25kg of PM10 from the air every year. If the air-filter was deployed on 2,500 buses across the UK, it could remove as much as 588kg of PM10 particles every year. In parallel, Bluestar has been fitting solar panels to buses, with a total of 19 vehicles to have them in place by the end of July. When five further buses are fitted with air filters, one of them will have a solar panel as well. This will enable a trial later this year to see whether solar energy can be used to make the air filter completely self-sufficient." -- https://www.bluestarbus.co.uk/air-filtering-bus-trial-succes....

Which goes to show you're far better off filtering at source while pollutants are at very high concentrations. Far better than trying to remove it when it's down to a few tens of µg / m⁻³.

A damn sight more efficient, and no doubt far cheaper too.

Which rather shows up filtering buses as a lovely bit of greenwashing to avoid mentioning lack of adequate UK regulation. Regulation requiring all polluters filter PM10 and PM2.5 at source -- chimney or tailpipe -- wouldn't be as much of a story, but would actually achieve something worthwhile.

It's interesting to note that the 65g was removed from the air over 9000 miles, which averages to particulate matter being produced at a rate of about 0.0045g/km. However, the parent article suggests that the buses have engines that conform to the Euro 6 standard, which according to Wikipedia[0] allows for up to 0.01g/kWh of particulate emission for heavy duty diesel engines in trucks and buses (0.0045g/km for all other categories). Given that [1] suggests energy consumption levels of around 2-5 kWh/km depending on powertrain type, it looks like the bus produces upwards of 5-10x the amount of pollution it actually cleans up.

So overall it looks like it would be more appropriate to market these buses as having a lower contribution to particulate matter pollution rather than actually cleaning up the air. Here's hoping that these buses actually transport people...

[0] https://en.wikipedia.org/wiki/European_emission_standards

[1] http://tf.llu.lv/conference/proceedings2015/Papers/060_Graur...

Did the tests determine if this effort actually improved ambient air quality, or just that the filters worked?

Interesting. But they did not say if the bus actually removed more pollutants than it creates on its own. As cars (and busses) do have some serious wear and tear on wheels and breaks.

> According to tests, audited by manufacturer Pall, and being assessed by the University of Southampton, the bus removed approximately 65g of pollutants from the air and cleaned 3.2 million cubic metres of the city’s air.

Removing more than the additional pollution released due to the extra weight and energy usage during driving and manufacturing would be enough I think, given that the bus is going to be driving anyway.

'...and being assessed by the University of Southampton'

It's ironic that Southampton is a city full of buses that often seem to be empty and creating chaos on roads never designed to accommodate them?

Hopefully Southampton can get it's shore power[0] sorted, the cruise ships idling are more a pollution problem than the busses.

[0] https://www.bbc.co.uk/news/uk-england-hampshire-50562113

Surely vacuuming the streets would remove more particles that would get airbourne.

This method uses a lot of fuel to filter outside air. Compared to a office that pumps the air through it anyway. Seems like expensive spin atm.

Reply on news.ycombinator.com