Tiles to reduce air pollution in a city, respiratory oases. I love it when architecture solves problems instead of creating them (ie suburbia):

The tiles are coated with titanium dioxide (TiO2), a pollution-fighting technology that is activated by ambient daylight. TiO2 is a photo-catalyst already known for its self-cleaning and germicidal qualities; it requires only small amounts of naturally occurring UV light and humidity to effectively reduce air pollutants into harmless amounts of carbon dioxide and water. When positioned near pollution sources, the tiles neutralize NOx and VOCs (volatile organic compounds) directly where they are generated. They transform previously inert urban surfaces into active surfaces, re-appropriate polluted spaces for safer pedestrian use, and invert problem spaces – dark, polluted, uninhabitable – to benevolent spaces that benefit communities.

2007-01-03: PigeonBlog

PigeonBlog enlists homing pigeons to participate in a grassroots scientific data gathering initiative designed to collect and distribute information about air quality conditions to the general public. Pigeons are equipped with custom-built miniature air pollution sensing devices enabled to send the collected localized information to an online server without delay. Pollution levels are visualized and plotted in real-time over Google’s mapping environment, thus allowing immediate access to the collected information to anyone with connection to the Internet.

2007-09-13: World’s most polluted places as a MyMap.
2014-06-29: US Air Quality Improvement. I like to highlight the occasional good news when it comes to the environment.

Air pollution has decreased even though population and the number of cars on the roads have increased. The shift is the result of regulations, technology improvements and economic change. New York City has seen a 32% decrease in nitrogen dioxide between the 2005-2007 and 2009-2011 periods.

2014-11-26: Pollution can be cleaned up quickly. This should make China’s pledge to improve air quality / reduce greenhouse gases quite feasible.

In 2002, South Korea was ranked 120th for air quality, and 43rd in 2014

2015-09-23: VW 1M tons of pollution. It is time to get tough, and destroy VW.

Volkswagen’s intentional fraud resulted in an extra 1M metric tons of air pollution being spewed into the skies over America; if they’d extended the con to Europe (where there are far more diesels), it would have been orders of magnitude worse.

2017-06-01: Electric Vehicles Are Cleaning Up

In regions that lean heavily on coal-fired power plants, plug-in cars can end up polluting more heavily at the smokestack than gasoline cars at their tailpipes. But as grids get greener, that’s becoming less true nationwide.

2017-06-17: Schlieren Imaging. This is what the world would look like if you could see invisible air currents, temperature gradients, and differences in pressure or composition of the air

2018-01-22: Far UVC disinfection. There’s part of the uv spectrum that kills viruses & bacteria, but does not damage skin.

2018-08-23: Too much CO2 affects sleep

If CO2 can affect sleep quality, that would explain how it could produce a whole-day effect. Strøm-Tejsen tests this on 16 subjects and finds that “objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO2 level was lower, as did next-day reported sleepiness and ability to concentrate and the subjects’ performance of a test of logical thinking.” Good things about this study: subjects were blinded to condition, the paper contains a pilot experiment and a main experiment which mostly replicate each other’s results. Bad things about this study: the experiments were about n = 15 each, the researchers didn’t correct for multiple comparisons, and they admit to manipulating the statistics surrounding their logical reasoning tests to get better results.

2020-08-23: Health benefits of clean air

Ditching fossil fuels would pay for itself through clean air alone. Over the next 50 years, keeping to the 2°C pathway would prevent 4.5m premature deaths, 3.5m hospitalizations and emergency room visits, and 300m lost workdays in the US.

2021-09-28: UV is very effective.

air filtration and UV disinfection can greatly reduce SARS-COV-II in hospital wards. The authors installed portable air filters with UV disinfection on 2 COVID hospital wards in the UK. The air was tested for viruses, bacteria and fungi before the filters were turned on, during the time the filters were on and then again after the filters were turned off. Airborne SARS-CoV-2 was detected in the ward on all 5 days before activation of air/UV filtration, but on 0 of the 5 days when the air/UV filter was operational; SARS-CoV-2 was again detected on 4 out of 5 days when the filter was off.

2022-03-28: 98% reduction in 5 minutes

“Far-UVC rapidly reduces the amount of active microbes in the indoor air to almost 0, making indoor air essentially as safe as outdoor air” The lamps inactivated more than 98% of the airborne microbes in 5 minutes. The low level of viable microbes was maintained over time, even though microbes continued to be sprayed into the room. The efficacy of different approaches to reducing indoor virus levels is usually measured in terms of equivalent air changes per hour. In this study, far-UVC lamps produced the equivalent of 184 equivalent air exchanges per hour. This surpasses any other approach to disinfecting occupied indoor spaces, where 5-20 equivalent air changes per hour is the best that can be achieved practically.

2022-08-19: Startups are entering this space to bring the cost down.

Beam ($5000) is an LED-based, upper room disinfection device that uses 265-nanometer ultraviolet light to create a disinfection zone located above people in a room. Vive ($3000), meanwhile, uses a wavelength known as far-UVC at 222-nanometers to inactivate harmful microorganisms in the air and on surfaces, even while people are present. While the Beam works in large open spaces, like classrooms and office lobbies, the Vive can be installed in smaller spaces, such as conference rooms and bathrooms. “What we have come to realize is that there is not one-size, fits-all for infection protection. What Arc competes with is some form of chemical intervention. For Beam and Vive, it’s HVAC upgrades.”

2022-10-28: Without massive improvements to LEDs, far UVC is not practical due to cost. Unclear what the deal with these startups is but I suspect they don’t output enough power to be effective.

$2000 is a ballpark retail price for a lamp installed by specialists, and the lamps have an expected lifetime of 15 months if they run continuously. There’s hope that far-UV lamps based on LEDs will eventually provide cheaper and longer-lived alternatives to the gas lamps currently being used, but prototype LED far-UV lamps are currently restricted to impractically low levels of power.

2023-09-15: Giant progress in China

China’s pollution levels in 2021 had fallen 42% from 2013. The improvement means the average Chinese citizen’s lifespan is now 2.2 years longer. Chinese cities used to dominate global rankings of the world’s worst air quality; while some are still on those lists, in many cases they have been overtaken by cities in South Asia and the Middle East. In 2021, Beijing recorded its best monthly air quality since records began in 2013. There is still work to do as China remains the world’s 13th most polluted country. And Beijing’s particulate pollution – the tiny but highly dangerous pollutants that can evade the human body’s usual defenses – is still 40% higher than in the most polluted county in the United States.

2024-05-08: What’s needed to make far UVC viable

Light in the 200-235 nm range, or far-UVC, is one of the most promising tools for dramatically reducing airborne transmission from day one of almost any pandemic caused by airborne pathogens. If adopted widely, it could also have a dramatic impact on seasonal flu, colds, and endemic COVID-19.

Unfortunately, progress on development and adoption has been much slower than one would have hoped. One bottleneck is the high cost and low efficiency of the only commercially available source at this wavelength range, 222 nm krypton chloride excimer lamps. For example, by our calculations, equipping a classroom with far-UVC would cost >$10k/classroom/year in lamps alone.
While directly supporting solid-state far-UVC R&D to accelerate availability is important, growing the far-UVC market in general and enabling greater private investment is even more critical.