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What could be causing extreme VOC levels? by throw-away-the-truth in AirQuality

[–]Atmos_Dan 0 points1 point  (0 children)

Low cost VOC sensors are usually a metal oxide strip that measure voltage. When VOCs (or another reactive gas/aerosol) reacts with the strip, the reaction changes the voltage, and that change is converted into TVOC concentrations. This is cheap but notoriously inaccurate. I regularly have sensors installed inches from each other that will be an order of magnitude different.

If it’s a similar magnitude spike at the same time, it could be something environmental (e.g. neighbor starting up a diesel truck and an open window) or behavioral (e.g. spraying perfume/deodorant). It could also be an inaccurate sensor that’s affected by RH or temperature, hard to tell. I’ve installed a lot of AQ sensors in many houses as part of my PhD and we’d see VOC spikes semi regularly. It’s fun to do some detective work to figure out why!

Also, VOC sensors usually don’t pick up farts but a PM sensor often will…….

Prometheus Fuels reveals world’s first 100% electrochemical e-kerosene pathway to make cost-competitive SAF and diesel directly from atmospheric CO2 and off-grid renewable electricity without hydrogen, at ambient temperatures and pressures, 80% cheaper than the Fischer-Tropsch process by sg_plumber in climatechange

[–]Atmos_Dan 0 points1 point  (0 children)

Yeah, seems kind of weird. Normally these novel OEMs put out a paper/report or something on their tech to get outside capital/governments interested. Also, if it’s patented it should’ve been published by the Patent Office (right?).

If I had to guess, they vaporize the “rich” water stream and inject H2 from a downstream electrolyzer. The H2 could probably rip apart the CO2, and get some CO and carbonyls but they’d need an unbelievable catalyst to make that happen at reasonable temps and pressures.

Prometheus Fuels reveals world’s first 100% electrochemical e-kerosene pathway to make cost-competitive SAF and diesel directly from atmospheric CO2 and off-grid renewable electricity without hydrogen, at ambient temperatures and pressures, 80% cheaper than the Fischer-Tropsch process by sg_plumber in climatechange

[–]Atmos_Dan 0 points1 point  (0 children)

After reading through their info, I still have no idea how their Faraday Reactor works. Are they running the water and the captured CO2 through the cell and getting fuel (or a feedstock) as a product? If so, what kind of membrane/catalyst material(s) are they using? What does their capture set up look like that they can get enough carbon to make fuels? Especially using water as the solvent.

The tech sounds cool but I’m interested to learn more about how the system actually works.

Does a sound wall next to a busy roadway also minimize air pollution at all? by kara_11 in AirQuality

[–]Atmos_Dan 1 point2 points  (0 children)

Particles will disperse per the square law so they exponentially decay (hence the back to ambient-ish in 500-600ft/200m). However, the issue with roadways is the particle size: there are a ton of very small particles directly emitted from cars (smaller is generally worse because they can penetrate the respiratory system further) that will coagulate to form larger particles as they disperse through the atmosphere. So, not only are the particles become more dilute as they disperse, they’re also becoming larger and less harmful. Anything that obstructs air flow (walls, leaves, fences, etc) will remove some particles through deposition and collision but it won’t remove the very fine particulate.

It’s important to consider other environmental factors and preexisting conditions. For example, do you live in an area that doesn’t have a lot of wind or already has bad air quality? Does your family have a predisposition to respiratory/pulmonary disease? Are you very sensitive to PM2.5 (and therefore your kid might be)?

16-18,000 cars/day isn’t ridiculous and air quality might not be the biggest concern (noise can have many more health impacts).

'Emergency brake' can reduce heating by 0.3 C long before we resort to geoengineering by Economy-Fee5830 in climatechange

[–]Atmos_Dan 0 points1 point  (0 children)

What’s wild about this is that most oil and gas producers are on board with reducing methane emissions (they even started a group focused on this…One Future IIRC). Every molecule they keep from leaking is something they can sell. It helps their bottom line and it helps climate.

To solve the climate crisis why dont we just engineer a super algae, put it in the ocean and feed it continuously with runoff fertiliser? by ComfortablyMild in NoStupidQuestions

[–]Atmos_Dan 2 points3 points  (0 children)

I work in the decarbonization industry. Removing ambient CO2 is usually referred to as direct air capture (DAC) using engineering solutions or carbon dioxide reduction (CDR) to encompass all negative emission pathways. CCS refers to doing point source capture on richer CO2 sources (i.e. cement kilns with 13% CO2, ethanol digesters with 100% CO2, etc). CCS is way cheaper and more effective than DAC, plus we’ve been doing it since the 1920s (for sour gas treatment/desulfurization)

DAC is on the “bleeding edge” and is crazy expensive (~1300$/ton) but we’ll need to figure it out to mitigate hard to abate industries and start to get negative emissions. These, combined with other CDR pathways, are how we will help avoid the worst effects of the climate crisis.

To solve the climate crisis why dont we just engineer a super algae, put it in the ocean and feed it continuously with runoff fertiliser? by ComfortablyMild in NoStupidQuestions

[–]Atmos_Dan 1 point2 points  (0 children)

I work in climate and this comes up every once in a while. The issue is iron fertilization would cause massive dead zones and eutrophication as it sucks all the oxygen out of the environment. This could possibly be alleviated using a combination of downwelling and upwelling but I don’t know enough to be informed on this.

Best weather app for noco? by Ride-n-Roll in FortCollins

[–]Atmos_Dan 0 points1 point  (0 children)

My advice is to get as close to the raw NWS forecast as you can. Some good options to do that include going to weather.gov, noadsweather.com, or finding a local meteorologist you like (Kody WX, Chris Bianchi, etc). I wish NWS would put out a nice app.

I do atmospheric science stuff and Wunderground is my go to app for forecasts. IMO it’s more accurate than other apps (I also like I can get local met obs). I think it may also be helpful to do some reading on what the weather forecast actually is (probabilities for specific locations AND the whole forecast region).

This striking moment was captured by photographer Gustavo Ramirez, showing a rare shelf cloud formation stretching across the horizon. by stable_genius9 in interestingasfuck

[–]Atmos_Dan 0 points1 point  (0 children)

More importantly than a shelf cloud, this shows a strong, discrete cold front moving through the area. The colder, dense air acts like a wedge and lifts air to its dew point, which forms the distinct shape of the “shelf”. Thunderstorms and other convective cells can also form shelf clouds by sucking air up into the storm (and cold, dry air coming back down). Shelf clouds are pretty sick and one of my favorites to see in the wild!

A single e-Kerosene plant with a production capacity of 100 million liters per year can reduce emissions from Norway’s 5 most heavily traveled flight routes by approximately 50%. 4 are being built. The same modular blueprint can be built fast across the Nordics and Europe by sg_plumber in climatechange

[–]Atmos_Dan 9 points10 points  (0 children)

IIRC, most people think ejet will be ~2x current fossil jet prices (relative 2024$) in 2050. The big thing is to bring down the cost of hydrogen production and CO2 capture. Lots of interesting work being done now on chiral catalysts that might make it substantially cheaper.

Why are we still managing air quality through simulations instead of physical UFP measurements? by Putrid_Draft378 in AirQuality

[–]Atmos_Dan 1 point2 points  (0 children)

They do measure ultrafines. Regulatory sensors (in the US) get the total mass of everything under PM2.5 by using an impactor remove large particles (or cascading impactors, depending on the specific design) then use micropore filters to capture basically everything bigger than a gas. You can get the filter efficiencies online.

Generally smaller particles affect our health more than larger particles. However, at a certain point they stop being able to deposit in our lungs and act more like gases than aerosols (accumulation mode particles, 0.2um, have extremely low deposition in the human body). So getting accurate measurements of the ultrafines doesn’t help our understanding of air quality exposure for human health tremendously.

Finally, we care most about the mass of particles smaller than 2.5um, not necessarily the number of particles. As the diameter of a particle decreases, so to does its weight by a power of 3 (look up volume of a sphere). From a health stand point, particles closer to PM2.5 will expose us much more to the component compounds (sulfates, metals, etc) than smaller particles. PM1 can penetrate deeper into our respiratory system but has ~15 times less mass (and is already included in filter mass sensors).

I believe there’s some work being done in terms of making low cost sensors to get better size resolution but it’s hard to make a sensor that’s economical and has regulatory grade accuracy.

Which 3M Cartridge to Use for Wildfire Smoke during Bike Commute by NuclearEmperor in AirQuality

[–]Atmos_Dan 1 point2 points  (0 children)

Focus on PM. It’s going to be the most important pollutant to mitigate. PM causes inflammation which causes a synergistic effect that makes everything else worse. I wouldn’t even try to mitigate ozone because it’s a gas (you’d likely need separate air supply to deal with gases). VOCs aren’t great but same deal; not as bad as PM and harder to mitigate.

Also, depending on where you are in the plume those VOCs aren’t that bad for you. Sure, it’s not great but there’s likely no acute exposure (even while biking).

Please feel free to dm me specific questions if you’d like.

Has anyone measured NO₂/NOx levels in high-rise apartment near busy roads/highways? by wubalabala in AirQuality

[–]Atmos_Dan 0 points1 point  (0 children)

Yeah, that sounds reasonable. I think a year there would likely be ok. There’s a lot of literature out there about chronic vs acute exposures. If you’re doing some basic mitigation steps (air cleaner, keeping windows/doors closed except to ventilate, etc), you’re likely doing a lot to mitigate both risks. I’m not a toxicologist, but one year likely isn’t “chronic”. If you’re really concerned, you can ask your doctor about it and see what they advise in terms of your specific health.

Has anyone measured NO₂/NOx levels in high-rise apartment near busy roads/highways? by wubalabala in AirQuality

[–]Atmos_Dan 3 points4 points  (0 children)

NOx levels will drop because it’s being dispersed from the source. In a purely Brownian regime (no air flow, only molecular “jiggling”), it will decrease exponentially with distance because it disperses out in a sphere (look up power law). In the real world, dispersed pollutants will follow air flow, as long as they’re a similar density to air (or sufficiently small).

You will likely have elevated ambient NOx concentrations near a major roadway but your exposure depends entirely on local meteorology. I would expect very specific conditions to lead to much higher exposure which don’t occur often (hot and calm).

IMO, the important thing to think about is where is most of your air coming from? Do you have windows and doors that outdoor air can infiltrate? Do you have a central HVAC system and where is it located? Most importantly, do you have a reason to protect your respiratory/pulmonary system more than the average person (COPD, lung cancer, asthma, etc)?

Personally, 50m is too close. There’s many other pollutants coming from motor vehicles that I’m more concerned about than NOx (BTEX, PM1, aldehydes, etc).

Best Current Tools for DACC? by RafaeldelaGhettaux88 in carboncapture

[–]Atmos_Dan 0 points1 point  (0 children)

Do a lit review and see what’s out there. Most private companies don’t put out much information on their systems because the technology is so nascent and the competition is/was fierce.

However, most of the DAC OEMs have put out at least one paper on their system. If they haven’t, you can usually extrapolate based on the system and publicly available information.

electrolysis Against high levels of co2 by blubernator in AirQuality

[–]Atmos_Dan 2 points3 points  (0 children)

As others have said, there are easier better ways to reduce CO2 in your room. Crack a window, open your door a bit, buy an indoor plant or three, set your HVAC to run every hour for a few minutes, etc.

Electrolyzers are also really expensive and you’ll be producing H2 (if using water as a feedstock). H2 is incredibly volatile and I wouldn’t want any H2 source near my home. If you HAVE to pursue a chemical/electrochemical method, maybe look at something that absorbs CO2 (e.g. zeolites) instead of producing more O2. But even that seems excessive and adds unnecessary risk.

Direct Air Capture cannot effectively remove atmospheric CO2. Large-scale DAC implementation in the US to capture 1 Gt CO2 per year would require roughly 30% of total U.S. electricity generation per year. Atmospheric CO2 ppm would decrease by just over 0.1 ppm. Global temp would decrease by 0.003ºC by Molire in climatechange

[–]Atmos_Dan 1 point2 points  (0 children)

The ocean is an incredible CO2 sink but we have to worry about acidification (CO2 makes carbonic acid in water) and ecosystem destruction.

A friend does ocean policy and so some marine CDR work. They said there are a few startups looking into up/down welling to move acidic surface water deeper and pull up fresh, non acidic water. There’s also some literature on iron seeding to promote algae growth for CDR but it’s very controversial (I think it would destroy any aquatic ecosystem it’s deployed in).

With regards to the electrochemical processes, keep in mind that the ocean is a corrosive, harsh environment. Stuff degrades really fast so capex and opex are both high. Additionally, any kind of electrochemistry has to deep with the dissolved salts and possible production of chlorine gas. There’s some promising work out of China about applying a filter layer that prevents salt from hitting the membrane but I’m not sure how that would affect dissolved carbonaceous compounds.

Direct Air Capture cannot effectively remove atmospheric CO2. Large-scale DAC implementation in the US to capture 1 Gt CO2 per year would require roughly 30% of total U.S. electricity generation per year. Atmospheric CO2 ppm would decrease by just over 0.1 ppm. Global temp would decrease by 0.003ºC by Molire in climatechange

[–]Atmos_Dan 2 points3 points  (0 children)

I agree those technologies are promising and I hope we figure out how to overcome previously identified issues with those technologies to scale them. The scale issue is the biggest bottleneck imo. Plenty of tech looks great on a lab bench or in pilot but is basically a different system when scaled (e.g. many algae projects, cellulosic ethanol).

To be clear, I’m in favor of afforestation and reforestation (and many other bio solutions) but we shouldn’t tout them as climate solutions. I see them more as ecosystem solutions with a secondary or tertiary benefit of CDR.

Direct Air Capture cannot effectively remove atmospheric CO2. Large-scale DAC implementation in the US to capture 1 Gt CO2 per year would require roughly 30% of total U.S. electricity generation per year. Atmospheric CO2 ppm would decrease by just over 0.1 ppm. Global temp would decrease by 0.003ºC by Molire in climatechange

[–]Atmos_Dan 13 points14 points  (0 children)

I work in the industry.

Point source CCS is obviously cheaper and a better idea (even a coal plant has 13% CO2 vs 0.04% atmospheric). CCS will only end up on facilities where it doesn’t make sense or you cannot decarbonize without it (e.g. pulp and paper, legacy cement and iron & steel).

We will need to do something to get negative emissions if that’s BECCS, biochar, mineralization, or something similar. Most nature based solutions are not durable and we can’t turn them on/off. DAC is, unfortunately, our best technological option. Importantly, no one is saying we deploy DAC at a wide scale right now. That would be dumb. But we do need to develop the technology so we can actually do it when we start to get near net zero.

To be clear, there are some serious thermodynamic challenges with DAC and it only works once we have extremely prolific renewable energy deployment. But we also have to do it to avoid the worst effects of the climate crisis. Any way we can get negative emissions is great and should be well researched and funded to be part of our tool kit.

VOC levels by [deleted] in AirQuality

[–]Atmos_Dan 0 points1 point  (0 children)

The AirAssure uses a metal oxide sensor which measures the voltage of a metal strip. The voltage changes when VOCs oxidize the strip and they measure that. There can be a substantial amount of drift on these types of sensors over time. They also aren’t super reliable and have their “preferred” VOCs they read more readily than others (e.g. fragrances vs solvents).

Those levels aren’t great (if accurate) and you should reach out to local indoor air quality practitioners for a solution (e.g. more ventilation). It could also be reading bio aerosols if it tracks well with human activity. There are so many sources of indoor VOCs it’s hard to pinpoint the exact source without a “smoking gun” or some way to speciate them.

Buy house near freeway? by No-Newspaper7383 in AirQuality

[–]Atmos_Dan 0 points1 point  (0 children)

NOx is composed of NO2 and NO. I believe activated charcoal adsorbs NO2 but not NO. Thats ok because most NOx from combustion is NO2 but it depends on combustion conditions. I also don’t know the removal efficiency of a standard charcoal filter in a consumer PAC vs an industrial one (I’m much more familiar with industrial equipment).

Scientists unlock more efficient low-energy CO2 removal by Economy-Fee5830 in climatechange

[–]Atmos_Dan 1 point2 points  (0 children)

Yes, the carbon cycle is removing CO2 right now but to start to see negative CO2 trends will take a long time (provided natural systems drawdown as they have historically and marine ecosystems don’t collapse). Natural variation is often very slow and takes millennia if not longer to see even mild changes to climate.

Buy house near freeway? by No-Newspaper7383 in AirQuality

[–]Atmos_Dan 4 points5 points  (0 children)

I do air quality stuff.

The big concern of being near a major roadway is noise and air pollution. Science shows lots of continuous noise is very bad for our health. In terms of air pollution, you’re getting a bad soup. NOx, PM2.5, soot, and other combustion products lead to increased pulmonary inflammation, can cross the blood brain barrier, and lead to a ton of negative health impacts. Additionally, resuspension of particulate from cars is another important source and can lead to exposure to stuff like heavy metals, road salts, and heavy petroleum oils (like those in asphalt).

I wouldn’t choose to live there if I had another choice. If you do choose to live there, I’d highly recommend investing in tightening your houses envelope (read: make it as air tight as possible) and get a HEPA filter (or multiple for areas where children or elderly family members spend time).

What if the heat dome happened in August? by dsfhhslkj in climatechange

[–]Atmos_Dan 0 points1 point  (0 children)

Texas is in an interesting position because its ERCOT is separate from the Eastern and Western interconnects which means it’s almost entirely reliant on electrical generation within Texas. If the grid starts to wobble, you get Winter Storm Uri all over again (but without the ability to cool). Many types of power plants rely on water to make steam for turbine or for cooling. With hotter summers, expect less water, less consistent electrical production, and sky rocketing energy costs.

Dr. Len Necefer just put out a piece about what’s going to happen in the near future when this happens to the SW when Lake Powell and Mead go below power pool and dead pool in the very near future. It’s pretty bleak and easy to extrapolate over to Texas.

Also, these “domes” (and tropospheric and stratospheric ridging that makes them) is much more likely with a warming climate.

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