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Hydrogen Peroxide as an Air Cleaner

Hydrogen Peroxide as an Air Cleaner

Hydrogen peroxide has been around for a long time.  The brown bottle you may keep in your bathroom as an antiseptic for treating wounds has many, many more uses!  It was discovered in 1818 by scientist Louis Jacques Thénard as he reacted barium peroxide with nitric acid.  Today, it’s still used medically, as well as in many diverse applications such as launching rockets and satellites into space, or as a more environmentally-friendly alternative to chlorine-based bleaching products in the manufacture of paper.   (Peroxide Power)

Hydrogen peroxide is chemically written as H2O2, meaning it has 2 hydrogen atoms and 2 oxygen atoms.  It is an oxidizing agent, releasing an oxygen atom when it decomposes.  Decomposition happens quickly in the presence of organic matter like microbes or reactive compounds (hence the bubbling fizzing action on wounds or with baking soda), but it will also decompose slowly in storage, which is why it’s sold in those brown bottles to protect it from light and the ambient air.  

Hydrogen peroxide can be used as a disinfectant in appropriate dilutions on surfaces, in laundry, and in the air.   In the air, hydrogen peroxide is safe in concentrations up to 1ppm according to the Occupational Safety and Health Administration (OSHA). Because it’s chemically very similar to water, it can be produced from water and decomposes into water.  Yet as common and beneficial of a substance as it is, bulk hydrogen peroxide is surprisingly hard to produce and transport.  Currently, large quantities of hydrogen peroxide are made through what’s known as the “anthraquinone process.” This method is energy-intense, requires large-scale production, and produces large quantities of carbon dioxide (CO2) as a byproduct. While directly reacting hydrogen and oxygen to make hydrogen peroxide would be ideal, thermodynamics prefers to form the more stable water (H2O) over hydrogen peroxide.  (Producing hydrogen peroxide when, and where, it’s needed)  However, since only a minimal amount of hydrogen peroxide is needed and proven safe to kill microbes in the air, purifiers are now using different technologies to produce “dry” hydrogen peroxide and distribute it for air cleaning.  Here are some examples:

  • Photohydroionization (PHI) is a technology developed by RGF Environmental Group that uses a broad-spectrum, high intensity UV light targeted on a hydrated quad-metallic catalyst. The UV light in conjunction with the catalyst promotes the conversion of naturally occurring water vapor into airborne molecules of hydrogen peroxide (H2O2). These airborne H2O2 molecules revert to oxygen and hydrogen once they have come in contact with a pollutant. (PHI) This company produces standalone and in-duct products.
  • The TADIRAN AIROW technology fractures Oxygen (O2) into two separate “O” molecules by using a discharge current. These “free O” atoms combine with the H2O molecules in the airflow, transforming into hydrogen peroxide (H2O2). The H2O2 is then distributed through the indoor unit of the air conditioner into the conditioned living space. The amount of hydrogen peroxide that Tadiran’s new TADIRAN AIROW releases into the conditioned space is below the safety requirement as determined by OSHA of 1ppm. TADIRAN AIROW has been proven to release less than 7ppb of hydrogen peroxide. (HYDROGEN PEROXIDE TECHNOLOGY FOR INDOOR AIR PURIFICATION)
  • AirROS purifiers utilize and create 7 species of ROS (Reactive Oxygen Species).  The first stage, which occurs inside the device, includes 5 of these ROS (atomic oxygen, singlet oxygen, hydroxyl radicals, superoxide and peroxynitrite), and 2 species (gas-phased H2O2- dry hydrogen peroxide and low concentration levels of O3-ozone) leave the reactor and move into the room for further disinfection.  According to AirROS, “...Dry Hydrogen Peroxide purifiers technology can only provide short-distance surface treatment within the air purifier because of the short life of hydrogen peroxide. If you have a surface not close to the purifier, it will be untreated and left vulnerable to contamination.  AirROS commercial air and surface purifiers offer long-distance surface treatment because of the Trioxidane that forms from O3 and H2O2 combined, which means you can treat any surface, no matter how far away it is from the purifier. As a result, it provides an added layer of protection against surface contamination and eliminates odor effectively.  Trioxidane decomposes very quickly in water but has a half-life of 16 minutes in normal ambient conditions, making it one of the longest lasting hydroxyl radicals. It’s theorized that the human body also produces trioxidane as a powerful oxidant against invading bacteria because the body also produces singlet oxygen and has lots of water, the two ingredients for making trioxidane.  (Trioxidane)
  • AsepticSure Oxidation by Medizone International (UK company) is a system that uses hydrogen peroxide and ozone to clean unmanned rooms. According to EPA registration, personnel must be trained, the room must be sealed, and the ozone generated can have severe effects on certain materials, such as natural rubber and nylon.  The time to disinfect, personnel required to operate the system and limitations (not to be used with contraindicative materials or with life-saving equipment or with personnel in the room), all seem to be quite restrictive, yet the system has been sold to and installed at many medical facilities.
  • A hydrogen peroxide generator composed of a TiO2 catalyst that is activated with UV light was studied in 2022.  The photocatalyst becomes activated by light given off by a nearby UV-A bulb which excites electrons across the bandgap of TiO2, converting water vapor in the air stream passing through the catalyst into H2O2.  The researchers were aware that it is theoretically possible that H2O2, OH radicals, and hydroperoxide radicals can enter an air stream that passes through an operating photocatalytic TiO2 structure. From an indoor air space standpoint, however, only H2O2 will survive long enough to be detected at distances greater than about 1 cm from the photocatalyst. Over time, the H2O2 that has entered the room will either react with organic species within the indoor space or decay naturally into the benign products, water and oxygen. Hydrogen peroxide can last up to 30 minutes, depending on temperature, humidity, and reactive contents in the room.

Limitations of dry hydrogen peroxide include:

  • Position of the unit: position is very important, because dry hydrogen peroxide has relatively high reactivity, which can diminish its effective lifetime. For instance, H2O2 is known to react with metal surfaces such as those provided by the metal ductwork in the bypass duct. As the pathlength between the device and the room becomes longer, the H2O2  concentration could possibly become diminished (due to reactions with the metal ducting) to a point where MS2 inactivation is minimal or no longer even occurs (2022 study Evaluation of a Gaseous Hydrogen Peroxide Generating Device). 
  • Sensitivity: The other product, trioxidane, is a product of ozone and hydrogen peroxide.  Although devices are restricted in ozone output in the US, those who have asthma or other respiratory issues may want to use them with caution. 

Photo by Bill Jelen on Unsplash

OH, the detergent of the atmosphere, and OH-, the ion that cleanses our homes’ air

OH, the detergent of the atmosphere, and OH-, the ion that cleanses our homes’ air

Did you know that earth’s atmosphere is self-cleaning, to an extent?  We would be A LOT worse off if it wasn’t.

OH, the hydroxyl radical, is the most important oxidizing species in the atmosphere.  In this article, we’re going to discuss how it’s formed in nature, what it does, and how it’s different from the hydroxide ion OH- that is formed in bipolar ionizers.  

You’ve probably heard that there is ozone in the earth’s atmosphere.  The majority of ozone is found in the stratosphere (about 10-25 miles above the earth), shielding us from the sun’s UV light and cosmic radiation.  This is where ozone can be destroyed by molecules that contain chlorine and bromine, such as chlorofluorocarbons (CFCs). (EPA.gov) About 10% of the ozone is found a bit lower, however, in the troposphere (where clouds are formed and planes fly).  In the troposphere, ozone performs a very important function by being a primary ingredient for the production of OH.  Here, UV energy from the sun (mostly in the UV-B range of 290-310nm)(Treatise on GeoChemistry, ch. Chemistry of the Hydroxyl Radical (OH) in the Troposphere), breaks down ozone (O3) into O + O2.  Then, in the presence of water vapor (there’s very little water vapor in the stratosphere, so this has to happen in the troposphere), the lone O molecule reacts with H2O to form 2 molecules of OH (hydroxyl radical).  

In chemistry, a radical, also called free radical, is a molecule that contains at least one unpaired electron.  OH is a radical which is highly reactive because of the configuration of electrons in its outermost shell.  Normally, atoms and molecules prefer to have 8 electrons in their outermost shell, making them most stable (called the Octet Rule), but they will compromise and share electrons if necessary.  OH has 7 electrons in its outer shell: 6 electrons are from the O atom and 1 electron from the H atom.  Each electron has a negative charge, but it is balanced by the same number of protons in the nuclei of the atoms, so that the total “charge” of the molecule remains neutral.  Electrons also like to be “paired”, and although each has a negative charge, they have opposing spin directions which causes them to seek to be “paired” with another electron.  The OH molecule constantly seeks one more electron to “pair” with the 7th electron in its outer shell.  OH only survives for nanoseconds after it is formed–because it can immediately steal that missing electron from most of the chemicals found in the troposphere.  This reaction of the OH with other molecules is called oxidation. 

(Oxidation: Despite the name, the presence of oxygen is not a requirement in an oxidation reaction.  The reaction is part of a transfer of electrons between two substances.  Oxidation occurs simultaneously with reduction in a type of chemical reaction called a reduction-oxidation or “redox” reaction.  The oxidized atom loses electrons, while the reduced atom gains electrons.  On earth, oxidation is usually an undesirable reaction.  Oxidation is another name for rust, corrosion, and breakdown of materials around us and in us.  Our bodies produce “anti-oxidants” to prevent breakdown of our cells. ) 

There are limitless reactions that can happen in the atmosphere, but OH reacts primarily with carbon monoxide (40%) to form carbon dioxide. Around 30% of the OH produced is removed from the atmosphere in reactions with organic compounds and 15% reacts with methane (CH4). The remaining 15% reacts with ozone (O3), hydroperoxy radicals (HO2) and hydrogen gas (H2). (Oxidation and OH Radicals)  With its supreme oxidation potential, hydroxyl radicals can react with molecules and chemicals that are otherwise extremely stubborn and resist oxidation. (Hydrogenlink.com)

Since OH is primarily formed with energy from the sun, OH production mainly happens during daylight hours.  The following map is a snapshot of a model showing how OH is generated as sunlight illuminates a rotating earth.  (The Atmosphere: Earth’s Security Blanket)  Because OH is so short-lived, it’s really hard to detect, so the formation or degradation of other chemicals is used to determine how much OH is in the atmosphere at any one time.  For example, this model is generated from the Tropospheric Emissions Spectrometer (TES) equipment on a NASA satellite.  TES measurements of a number of other chemical elements influenced by OH, such as ozone, carbon monoxide and nitrogen dioxide, have enabled scientists to better represent OH in these models.

Did you know that humans also generate OH indoors? (Science Daily)  Indoor air can have higher (but not dangerous) levels of ozone, which reacts with certain oils on our skin. The reaction releases a host of gas phase chemicals containing double bonds that react further in the air with ozone to generate substantial levels of OH radicals.  It’s a very new discovery (2022), which was aided with extensive computer modeling.  This is important to know, because although they are great to have in the upper level of the troposphere,  we don’t want high levels of hydroxyl radicals indoors.  They can damage tissue and frequently initiate chain reactions with other radicals and VOCs, able to produce harmful chemicals like formaldehyde. 

So far we’ve talked solely about the hydroxyl radical, OH.  This chemical formula looks similar to hydroxide ions, OH-, produced by bipolar devices like the Germ Defender, Air Angel and Whole-Home Ionizer, but they are VERY different.  Even though the hydroxyl radical OH has an unpaired electron, that molecule as a whole is considered to have a neutral charge. The hydroxide ion, on the other hand, OH-, does not have any unpaired electrons, and has a negative charge by gaining an extra electron from a hydrogen atom.   OH- is made in bipolar devices when electricity is passed through water vapor in the air, splitting the water vapor into H+ and OH- ions.  A Japanese microbial study also confirms splitting of water vapor into positive (H+) and negative (O2-) ions.  H+ ions consist essentially of the hydrogen proton, which is very small; this positively charged ion does not last long in the air, as it is quickly attracted to and absorbed by larger molecules.  When the OH- ion encounters a microbe, it behaves as a hydroxyl radical, and tends to steal a hydrogen molecule from the surface of the microbe to balance out its negative charge, which damages the surface of the microbe and renders it unable to infect.  When they encounter a positively charged dust particle, OH- ions increase the total weight of the particle and cause it to drop out of the air.  They can also react with VOCs in the air.  Therefore hydroxide ions (OH-) have many of the air cleaning capabilities of hydroxyl radicals, without the harmful effects.  They are also longer-lived, lasting about a minute in the air, so they have time to permeate a room and create a sanitizing effect.  OH- ions are found naturally in larger concentrations near waterfalls, in the atmosphere after lightning, and in forests, causing the air to have that fresh, clean smell.   By releasing OH- ions indoors, bipolar ionization is all about bringing the best of the outdoors, indoors!

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It’s not the heat, it’s the air pollution!

It’s not the heat, it’s the humidity air pollution!

Decades ago, when the meteorologists predicted extreme heat, it seemed they only advised on the necessity to stay out of the sun, drink more water, and cool off more frequently (stay in the pool, yayyyy!).  Now, heat advisories come with more sinister warnings about air pollution levels, and the outdoors are less fun.  How did that happen?  The answer lies in meteorology and chemistry, all cooked up in our atmosphere.

Low-pressure systems are quite famous for moving rapidly across the US and bringing devastating weather like severe thunderstorms, hail and tornadoes.  They can also sweep pollutants like smoke and smog to other states.  High-pressure systems, on the other hand, typically cause stagnant air, which can concentrate pollutants over one area.  (scied.ucar.edu)  A “Heat Dome” is an area of high pressure that parks over a region like a lid on a pot, trapping heat. (National Geographic) A Heat Dome caused about 600 deaths in June 2021 in the Pacific NorthWest as a 1-in-1000-year event.  The heat, which broke Portland’s all time record of 107 degrees, was bad enough, but extreme heat combined with stagnant air during a heatwave increases the amount of ozone pollution and particulate pollution. (metone.com)  Here is where the chemistry comes in.

“Ground-level ozone pollution forms when heat and sunlight trigger a reaction between two other pollutants, nitrogen oxide and volatile organic compounds — which come from cars, industrial facilities, and oil and gas extraction. High temperatures therefore make ozone pollution more likely to form and harder to clean up. Drought and heat also increase the risk of wildfire, which can make air quality worse as smoke drives up levels of fine particulate matter — also known as PM2.5, or soot...Both ozone and PM2.5 carry major health risks. Ozone can cause acute symptoms, including coughing and inflamed airways, and chronic effects, including asthma and increased diabetes risk. PM2.5 exposure can lead to an increased risk of asthma, heart attack, and strokes. Globally, long-term exposure to PM2.5 caused one in five deaths in 2018, including 350,000 deaths in the United States.” (Heat waves can be life-threatening for more reasons than one)

Because of the increase in cars and industry, extreme heat forecasts are not just requirements to have bottled water and popsicles on hand and check that our elderly neighbors’ air conditioning is working.  It’s a time to make sure that those who have asthma, heart and vascular conditions stay indoors, and that you take the proper air pollution precautions, too. 

Unlike outdoor air filled with wildfire smoke, ozone and smog are not as visible and may not affect everyone immediately, but they are dangerous pollutants and shouldn’t be allowed in our homes.  Here are some steps you can take to prepare for that heatwave, and the resulting air pollution that often accompanies it!  

  • Seal doors and windows with weatherstripping, caulk and door sweeps.  

  • Find out how to adjust your HVAC system accordingly: you’ll want to close the fresh air intake and change over to recirculation, no matter whether you have central AC, a window air conditioner or portable air conditioner.

  • Purchase extra MERV 13 filters for your HVAC system, to be used on poor air quality days (caution: read our post on HVAC filters first, as using a filter with too high MERV rating can damage your system). 

  • If you live in an apartment building or condo with little control over the HVAC, consider purchasing vent filter material so you can place them in the vents into your space.  The filter material can prevent smaller particulates in smog from entering.  Carbon vent filter material will neutralize many VOCs as well.

  • Purchase a HEPA air cleaner (non-ozone producing type) and be sure to have an extra filter or two on hand.  The use of a HEPA filter will take much of the damaging fine particles out of the air you breathe!  Whenever there is bad air quality outside, run the cleaner/purifier on high for an hour and thereafter at "quiet"/medium setting (Wirecutter).  You can check out our post on standalone HEPA filters as a purchase guide.  If you can't purchase one, make one: there are many videos and instructionals online for DIY air cleaners; most only require one or more filters, a box fan, and some cardboard and tape.

  • Keep a stash of N95 respirator masks on hand.  These are a good source of protection if you have to go outside, or if power is cut to your home and indoor air quality gets bad as well.  The “95” means it blocks out 95% of particulates.   

  • Keep canned and non-perishable food on hand, so that you don’t have to cook during periods of bad air quality.  Cooking indoors increases small particulates and vapors in the air, and you won’t want to turn on your stove exhaust, as that will draw polluted outdoor air into the house.

  • If air quality is very poor (check next point), you’ll want to evacuate to a place with clean, filtered air, like indoor malls, libraries, community centers, civic centers and local government buildings (sfgate.com). 

  • Check your local air quality and receive updates from airnow.gov . Using an Air Quality Index (AQI) as a measuring tool ranging from 0-500, your local forecast and larger maps can be color coded to show whether an area is good (green), moderate (yellow), unhealthy for sensitive groups (orange), unhealthy (red), very unhealthy (purple), and hazardous (maroon).

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“Rust” in your sinks and toilets? Iron in your water can mean iron bacteria in the water

“Rust” in your sinks and toilets?  Iron in your water can mean iron bacteria in the water

Wait–is that rust in my toilet?  Why is the toilet looking rusty?  You might initially think that the pipes supplying the water might be rusting, and that could be a problem (however, it’s rare).  But if you know that there are no iron pipes supplying your water (if you live in the country with your own well), then you know that pipe rust is not the source of the problem.  Most likely it has to do with high iron content in the water itself, and a certain bacteria that consumes iron. At least 18 types of bacteria are classified as iron bacteria, long thread-like bacteria that “feed” on iron and secrete slime. Unlike most bacteria, which feed on organic matter, iron bacteria fulfill their energy requirements by oxidizing ferrous iron into ferric iron. (Iron Bacteria in Surface Water). 

Iron bacteria are small living organisms that naturally occur in soil, shallow groundwater, and surface waters. These bacteria combine iron (or manganese) in the soil, and oxygen to form deposits of "rust," bacterial cells, and a slimy material that sticks the bacteria to well pipes, pumps, and plumbing fixtures.  These iron bacteria don’t cause disease, but they can create an environment where other disease-causing microbes can grow (like coliform bacteria).  Iron bacteria can get into the well when the water in the well comes into contact with the soil surrounding it, or lakewater, or any rivers and streams.  (Iron Bacteria in Well Water)

If you haven’t had any work on your water system done, and you’re still suspecting the bacteria are feeding on iron pipes, here are the most common types of pipes (from 7 Types of Plumbing Pipes Used in Homes):

  1. Rigid copper pipe (water supply)

  2. PEX pipe (water supply)

  3. PVC pipe (water supply and drains)

  4. ABS pipe (drains and vent lines)

  5. Flexi Pipe (water supply)

  6. Galvanized steel and cast iron (outdated for water supply and drains)

  7. Black pipe (only used on natural gas lines)

So, you can see that out of the 5 water supply line types, only 1 has iron in it (#6) and those are considered outdated.  The cast iron and steel pipes that were used in the 1950s have gradually been replaced by one of the other plastics mentioned above.  (A Brief History of Pipe Materials)  Therefore, if your home was built after the 1960’s, it would be very common for you to have iron in the water supply lines. 

Other than causing brown stains, iron bacteria can also cause the following (Iron Bacteria in Well Water):

  • Smells: Swampy, oily or petroleum, cucumber, sewage, rotten vegetation, or musty smells, which may be more noticeable after the water has not been used for a while.

  • Colors: Yellow, orange, red, or brown stains and colored water, or a rainbow colored, oil-like sheen.

  • Deposits: Sticky rusty, yellow, brown, or grey slime, or “feathery" or filamentous growths (especially in standing water).

These are not the kinds of things you want to see in your sink or toilet!  It can also have detrimental effects on any water softening system, making the water running through it to have an off taste.  To confirm that the problem is iron bacteria, you can get the water tested by a lab.

If you do have iron bacteria, and states like Minnesota have a lot of it, it can be hard to get rid of.  Here are some steps you may consider: 

  • If you have a heavy concentration of iron bacteria, the best first step is to have the contractor remove and clean the pumping equipment, and scrub the well casing with brushes.  Make sure that they do not lay any of the equipment on the bare ground, as this could re-contaminate it!  

  • Next is chemical treatment, which is also for minor contaminations.  Treatment involves 3 steps: disinfection (or oxidation), retention time, and filtration. (How to Remove Iron Bacteria in Your Water)  Chlorine (bleach), hydrogen peroxide and ozone are frequently used.  Although many companies call all three of these “disinfectants”, the fact is that only chlorine is a disinfectant; hydrogen peroxide and ozone are oxidizers.  Disinfection is the act of killing bacteria, while oxidation causes a molecule, atom or ion to lose an electron (which also kills bacteria as a consequence).

    • Chlorine (bleach): Although bleach is cheap and will disinfect, its reactions to organic matter that may be in the water are not good–like haloacetic acids (HAAs) and trihalomethanes (THMs), which are classified as possible human carcinogens.  For more information on these byproducts, check out our article here.  

    • Of the two remaining, ozone is a stronger oxidizer than hydrogen peroxide, but hydrogen peroxide systems are less expensive and more readily available from water treatment companies.  According to USWater, extreme amounts of iron and hydrogen sulfide can be removed from the water supply effectively and consistently, it does not need a “contact tank” for retention time, and it does not cause maintenance issues with injection pumps as chlorine does.  (Chlorine or Hydrogen Peroxide – Which is Better for Treating Water?) does not have these byproducts and in addition, has several benefits: it can also rid water of hydrogen sulfide (H2S) smells (rotten eggs), and activated carbon filters used after disinfection last much longer than when used with hydrogen peroxide than with chlorine. (Eliminate Well Water Odors: Four Reasons Why Hydrogen Peroxide Water Treatment Is Best)  According the to Minnesota Rural Water Association, potassium permanganate is also a strong oxidizer that is in common use in Minnesota to remove iron and manganese. (Iron and Manganese)

    • Retention time is needed for chlorine to work, therefore the chlorine must sit in the well for a certain period, or if you are using chlorine as a continuous disinfectant, a holding tank is usually set up, with the size being dependent on your household’s normal flow rate (water usage rate).

    • Filtration is necessary to remove by-products (in the case of chlorine) and iron products (in all cases).   When chlorine contacts iron in the water, it changes the iron from a ferrous state to a ferric state, making it an insoluble particulate.  This is the state that can be easily filtered.  There are various types of filters available, the most common being activated carbon.  Reverse osmosis and some other types of filtration can remove iron from water without oxidation, and treating your water from the point it enters your home is important for all your appliances, but the iron bacteria may still thrive in your well and cause clogs up to the water treatment point. Iron can clog wells, pumps, sprinklers, dishwashers, and other devices over time. (Iron in Well Water)

If you notice these signs of brown or different colored stains, bad smell or slime deposits in your sinks or toilets, it’s a good idea to get your water tested for iron.  If iron bacteria are present, it’s likely a common problem in your area, and there are local companies who can provide the equipment needed to remove it.  However, it’s best to do your own research on these solutions to make sure that a company doesn’t try to sell you unnecessary equipment (such as a retention tank for a hydrogen peroxide system), and also it’s a good idea to get references and reviews from actual customers.

How droughts can even impact your air

How droughts can even impact your air

It’s been an unusual year.  In the southeast US, temperatures have been above normal with extended periods of no rain.  In the west, Lake Mead and Lake Powell have lowered by nearly 75% of where lake levels once were as the country's two largest reservoirs.  The Colorado River, which supplies these lakes, is used by seven surrounding states, and for decades annually the region was taking out about 1 million acre-feet of water more than the river was providing (Los Angeles Times).  Much of the country is in drought, and the Southwest is experiencing a megadrought–one it has not seen in 1,200 years. 

What is drought?  Drought arises only after a prolonged (>week) period of precipitation shortage that causes soil to dry up, and these period(s) may reoccur monthly.  Further, the prominent feature of drought is water deficit in both the atmosphere and the land component (e.g., soil and vegetation), resulting from the combination of precipitation shortage and increasing evapotranspirative water loss driven in part by high temperatures.   (2017 study).  When drought hits home, it’s more than water restrictions on your lawn. Here are some of the effects: 

  • Droughts increase ozone and PM2.5. A study released in 2017 examined air quality during 4 severe droughts and found that elevated ozone and PM2.5 are attributed to the combined effects of drought on deposition, natural emissions (wildfires, biogenic volatile organic compounds (BVOCs), and dust), and chemistry. In our post “It’s not the heat, it’s the humidity air pollution”,we noted the correlation between extreme heat and ozone.  Here are some other facts brought forth by the 2017 study: 

    • Meteorological conditions/extremes likely to co-occur with drought that are also associated with higher pollution levels. For example, high ozone is more likely to occur with high temperature and low RH (2016 study; 2017 study, 2016 study 2)

    • more frequent stagnation and heat waves could explain up to 40 % of the ozone and PM2.5 enhancements during drought

    • Since anthropogenic sources of ozone and PM2.5 have decreased significantly since 1990, the ozone and PM2.5 enhancements during drought are largely responses of natural processes from the land biosphere and abnormal atmospheric conditions. 

  • Droughts affect plants and their interaction with atmospheric ozone in complicated ways.  Some plants take in ground-level ozone, while other plants emit isoprene, a VOC that reacts with other atmospheric chemicals to create ozone. (Scientific American).  While studying the 2011-2015 drought in California, scientists found that: 

    • Dry conditions caused the plants to restrict water loss by closing their stomata (pores), which means taking in less ozone (ozone levels rose). Absorption did drop by about 15% during the most severe years of the drought.

    • Plants and trees were able to sustain isoprene production during the first three years by drawing on their carbon stores; isoprene helps them against heat stress. 

    • After 4 years, isoprene production dropped, and so did ozone (by 20%).  

  • Drying lakebeds (like the Great Salt Lake in Utah) expose people to toxic elements like arsenic when dust storms pick up lake bed dust, which are residuals of pesticides and agricultural chemicals that migrated into the lake over many decades.. (New York Times)  Another dried lake that causes air quality problems is Owens Lake in California, which is the country’s largest source of PM10 (geochange.er.gov).

  • Droughts can increase transmission of soil and dust-transmitted diseases like Valley Fever, which is coccidiodomycosis (Cocci for short).  Dust that is liberated from the soil during digging activities or dry, windy conditions can carry the fungus, which workers or residents can breathe in.  It causes symptoms like fever, cough and tiredness, but can occasionally be serious or deadly.

  • Trees and plants weakened by drought are more vulnerable to pests and disease, which can kill large numbers of them. Plants that succumb to drought and die cause several problems:

    • they turn from absorbing ozone and CO2 to emitting carbon via CO2.  

    • Dead plants and trees increase the risk of wildfires.

  • Droughts impact electric power generation systems (the Grid)in the following ways (americanscientist.org):

    • Hydropower is reduced because of low stream flow

    • Demand for electricity increases because increased cooling is needed in homes and offices 

    • Fossil-fuel plants (coal, natural gas) must increase production of electricity.

    • This means that air pollution increases during drought due to our electric power generation system. IF changes can be made to shift to “cleaner” generators (ie. natural gas instead of coal) during drought, it is generally better for air quality. 

In all, drought is a serious, complicated blight on both the land and the air, which we at HypoAir have felt for some time because California has been in long-term drought.  Finding ways to reduce water and energy consumption helps everyone, so don’t wait until regulations forces change–here’s a list of ways you can help your community and family before and during drought.  However, it’s the unseen increases in ozone, PM2.5, fungus and other forms of air pollution for which the public generally doesn’t prepare.  Here are some ways you can be smarter about air pollution from drought:

  • Continue to work on air sealing your home

  • Have extra MERV 13 furnace filters, air purifier filters, and filter media on hand so that you can change these more frequently

  • Have N95 respirators on hand for the immune-impaired who need to go outside 

  • Be cautious about excavation and construction work in areas where Valley Fever is a risk (wear an N95 mask if necessary)

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