Just What We Needed Dept.: An Air-Filtering Diesel Bus

CC BY 2.0 Not the actual Bluestar bus, this one is in Wikipedia. Not the actual Bluestar bus, this one is in Wikipedia

I think they are missing something, or I am missing something, but this seems like the dumbest idea ever.

Diesel exhaust is deadly, containing nitrogen oxides and particulates. So what is British bus company Go-Ahead doing about it? They are putting specially designed air filters on the roofs of their buses, to clean the air as it travels.

“We want this pilot to show that buses should be looked at as not just the solution to congestion in cities, but also as a solution to the air quality problem,” said Go-Ahead’s Chief Executive, David Brown. “As the bus removes the ultrafine particles from the air as it travels along the route, it is helping solve the air quality problems of the city. This bus will clean the air on its route 1.7 times a year to a height of 10 metres - imagine the change we could make to air quality if all buses had this technology.”

The press release says that the filter is made by Pall Aerospace, and that "if all Bluestar buses were fitted with this technology it would clean the air in the Southampton area 16 times a year to a height on 10 metres."

Now, to be honest, I do not know what this means, cleaning all the air to a height of 10m. The bus is not 30 feet tall sucking air in from everywhere around it. I do not know how Pall Aerospace Director of Marketing can say, “We used our knowledge of aerospace filtration to design and build a product that will help clean the air of the cities in which we live by removing the particulates that are a major component of air pollution,” when particulates are coming out of the back of the bus.

Here is a photo of the actual bus, with the filter visible on top. It is evidently an "engine barrier-type filter construction which is designed for particle removal efficiency of 99.5 percent without any impact on the passenger or travel experience." But if you stick anything on the roof of the bus it is going to increase air resistance and fuel consumption -- which is going to increase particulates coming out of the back of the bus.

I am not alone in thinking this is totally idiotic. You have weird claims of cleaning all the air in Southampton to 10m high when it is a little box adding drag to a diesel exhaust-spewing bus. If it is so effective, why don't they drag it behind the bus and clean up after themselves? Or just get rid of diesel buses?