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Can my indoor air quality affect the food I eat?

Can my indoor air quality affect the food I eat?

Do you ever look at the food on your countertop, whether it’s an apple pie or bowl of potatoes, and wonder, how did that food go bad so fast?  It’s a common problem, even more so in warmer climates, so we thought you’d like to know how your indoor air quality affects your food!

Admittedly, not all spoilage comes from your own air.  It’s been recognized that food processing plants need to have better air contamination control during the food production process.  “Primary  air  pollutants  in  the food  industry  are marked,  being,  in addition  to  microorganisms, suspended particles, combustion  products (nitrogen oxide,  carbon monoxide, carbon dioxide,  sulfur oxide) and volatile organic substances.” (2019 Meat Industry Conference Paper)  The contamination of food products is dependent on:

  • air’s microbial load, and 

  • on the duration of exposure to the air, whether during specific technological processing stages (e.g. cooling) or during storage (from book: Hygienic Design of Food Factories, chapter 14: Managing Airflow and Air Filtration to Improve hygiene in food factories).  

Air in slaughterhouses and sausage production facilities, for example, is more than 10 times more laden with yeasts and molds than dairy processing facilities, because of contamination that can come in on the product (animal feces).  The second point is that the product contact with air needs to be limited in order to limit its contamination.  Air  quality  is  particularly  important  in facilities for  production and packaging of butter, if this is manufactured in open-type mixers, since these devices can also incorporate up to 5% of the surrounding air into the product [Varnam  A  and Sutherland  J  P  1996 Milk  and  Milk  Products: Technology,  Chemistry  and Microbiology 1st ed, Chapman and Hall, London, p 451].

Another factor that causes spoilage during food processing is humidity.  There are three ways that humidity affects the food: 

  • Condensation on equipment and food can accelerate microorganism growth

  • Dry foods can absorb moisture that will lead to microorganism growth

  • Packaging like paper and metal start to degrade, leading to spoilage

These insights into how food gets contaminated in factories are good for application in the home because although we can’t much control how it gets packaged, we can certainly control how it’s stored and prepared at home.  So let’s dive in…

The three main biological pollutants that cause food spoilage are bacteria, yeasts and molds. (online course)  Bacteria, yeasts and molds, which are typically small in size, can hitch a ride on larger particles like water droplets or dust.  Where do these come from?

The bathroom.  It’s not pleasant to think about, but “Germs will more likely spread after you flush, when bits of fecal matter blast into the air in aerosol form, a phenomenon known as "toilet plume." From there, Kelly Reynolds (a public health researcher at the University of Arizona) said, the "bits of fecal matter settle on surfaces, contaminate hands and then get spread to the eyes, nose or mouth." (USAToday.com)  Here are some ways to limit the spread of germs from the bathroom to the kitchen: 

  • Close the toilet lid before you flush.

  • Wash and dry hands before leaving the bathroom

  • Use an ionizer like the Germ Defender in the bathroom, to kill germs in the air and on surfaces.

Pets.  Similar to the slaughterhouse scenario, many of us have furry animals (pets) walking around in our food-processing facilities (kitchens).  Where these pets have been and what they have on their fur and feet can be really disgusting!  Worse, homes with litterboxes in the kitchen, or allowing pets to walk on the counters, is like placing a toilet in the kitchen or even on the countertop!  It’s just not pleasant to think about.  If you have pets and you have a kitchen, think about these reforms:

  • Bathing pets regularly so that bacteria and mold are minimized

  • Not allowing pets to walk on countertops

  • Keeping litterboxes in another area of the home away from the kitchen if possible

  • Spraying pets’ fur regularly with a safe anti-microbial spray like Remedy Mold Treatment Spray by CitriSafe.

  • Always wash your hands after touching your pets and especially before food preparation!

The refrigerator.  What?  How can the refrigerator work against us when we’re talking about food spoilage?  Actually, I’m not talking about inside the refrigerator, although that can be a problem (more on that later).  Here, let’s talk about what happens in the “guts” of the refrigerator, where the heat is actually released through the coils.  The speaker is Jeff May, a renowned air quality inspector.  

“I was sitting in my kitchen, and every once in a while, I’d start to wheeze, but just couldn’t understand why. One day, I realized every time the refrigerator turned on, I would have trouble breathing. Our refrigerator was only three years old, but in those days, the drip pan was accessible from the front. When I removed the grille and took it out, there was a pearl onion that somehow bounced into it. The onion had an inch and a half of Penicillium mold growing on it. So, every time the compressor turned on, it would blow mold spores out into the room. Every frost-free refrigerator has a heating cycle. The cooling coil gets full of ice, and you have to melt that ice in order for the refrigerator to cool. The water from that melt goes into a pan at the bottom. The heat from the compressor is supposed to evaporate the water, but very often, the water persists. There’s just not enough heat. So, if there’s any dust in that pan, mold growth ensues. And if you’re allergic to cats and dogs, and somebody had a pet in the house before you moved in, that refrigerator can be a perpetual source of allergens just from the dust that accumulated on the coils when the pets were there. We’ve had people who have just simply cleaned their refrigerator, and all of their allergies went away.” (Jeff May, during interview with author of moldfreeliving.com)

Now for the inside of the refrigerator: Ok, it seems like a no-brainer that you shouldn’t leave spilled food lying around in the fridge because it can contaminate other food by direct contact.  But using your fridge properly also prevents spoilage:

  • The real reason there is a Fruits and Veggies Drawer: it controls humidity in the drawer and prevents certain foods from ripening too fast.  If there is a vent or slot on the drawer, this is used to adjust the humidity and air flow (because ripening fruits also produce a gas called ethylene, which will cause other fruits exposed to it to ripen).  Closed vent or no vent = high humidity, and Open Vent = low humidity.  For a quick way to remember what to put in the “Crisper Drawers”, remember this rule of thumb: “rot-low, wilt-high.” Fruits that are prone to rot belong in the low-humidity drawer, while produce that's prone to wilting needs to be enclosed completely in the high-humidity drawer. (for a full explanation see article at epicurious.com)

  • Don’t put meat, cheese, milk and eggs in the door shelves!   The door of the refrigerator tends to stay at a higher temperature and these items will spoil more quickly (with nasty consequences) when stored there.  For more on where to store what food, this article helps a lot).

The FoodKeeper App from the FDA is a useful tool to determine how long to keep, and when to throw out specific foods.  It is also helpful to know why you need to preserve foods by refrigerating or freezing them right away (within  2 hours of cooking).  Bacteria are not killed by these colder temps, but their growth is slowed down or stopped.  Some bacteria and their endotoxins (toxins released by the bacteria through its life cycle and during death) are highly resistant to heat, so thoroughly re-heating them before eating does not kill the toxin! (check out our post on endo-and exotoxins here).  Staphylococcus aureus is one example of such a bacteria, and it can cause some serious food poisoning, even death.  

The dishwasher. Wait–the dishwasher is supposed to clean my dirty dishes, how can it be polluting my kitchen air?  If you have ever cleaned the vent on your dishwasher, you will know how absolutely filthy this spot can be.  Food residue, along with moist, steamy air will cause a thick slime to grow.  The rest of the dishwasher needs a deep clean too (not just using a bowl of vinegar and/or baking soda), but the vent especially is the area where escaping steam will carry bacteria into your kitchen air. 

Finally, keeping proper humidity in your home is super-important not only for your sinuses, but for food preservation too.  Some fruits and veggies should only be stored on the counter (check them out here), so the proper humidity will help them to stay fresh longer.  

Now you know how good air quality in your home means better food (especially in your kitchen).  By reducing the bacteria-load in the air, reducing exposure to the air, and keeping proper humidity in the air, you can waste your precious foods less, and enjoy them more!

What are Endotoxins and Exotoxins and where do they come from?

What are Endotoxins and Exotoxins and where do they come from?

The word “toxin” causes my ears and eyes to perk up, because these are the types of substances that cause illness and even death.  Thankfully, it is increasingly possible to avoid toxins by understanding where they live and how they’re spread.   Science is advancing very rapidly to show us how to manage our environments, food, lifestyle and even our bodies to live more healthfully.   Endotoxins come from Gram-negative bacteria, and Exotoxins can come from either Gram-positive or -negative bacteria so we’ll start with what the “Gram” test means. 

Bacteria can be classed into two different groups: “Gram-negative” or “Gram-positive”.  These classes are based on a test developed by scientist Chritian Gram in 1884, which differentiates the bacteria using a purple stain.   According to webmd.com, bacteria either have a hard, outer shell, or a thick, mesh-like membrane called peptidoglycan.  The hard outer shell will resist the purple stain, and show up as a red color.  These are called “gram negative” because the purple stain did not show.  Bacteria with the peptidoglycan absorb the purple stain much more easily and are called “gram positive”.  The stain also tells more characteristics about the bacteria and the way it interacts with treatment. 

The peptidoglycan layer of Gram-negative bacteria is much thinner than that of gram-positive bacilli; instead Gram-negative have a hard, protective outer shell, making them harder to kill because of their harder cell wall.  When their cell wall is disturbed, or the bacteria are dead or dying, gram-negative bacteria release endotoxins that can make symptoms of illness worse.  In contrast, exotoxins are produced inside the bacteria and may be released while the bacteria cell is living, or during its death.

Here is a diagram that shows how the exo- and endo-toxins are released (source: microbiologyinfo.com).  (I distinguish them by remembering that endotoxins are only emitted at the “end” of life of the bacteria):

Here are some examples of gram-negative bacteria diseases (webmd.com):

  • Vibrio cholerae (Cholera, a serious intestinal infection)
  • E. coli (E. Coli infection)
  • Yersinia pestis (Plague, an infection of the lymph nodes and lungs)
  •  Bartonella henselae (Cat-scratch disease)
  • H. Pylori (gastritis, peptic ulcer disease, gastric lymphoma, and gastric cancer)
  • Campylobacter (campylobacteriosis, an infection that usually affects the digestive tract)
  • Legionella bacteria (Legionnaire's disease, a lung infection)
  • Salmonella (salmonellosis, a digestive infection caused by contaminated food)

Here are some Gram-positive bacteria (and the infections they cause): 

  • Staphylococcus aureus (MRSA, toxic shock)
  • Streptococcus group A (strep throat, toxic shock)
  • Clostridium botulinum (botulism)
  • Bacillus anthracis (Anthrax) 

As you can see, endotoxins and exotoxins are a serious matter!  Here are some of the other important differences between them (byjus.com):

Endotoxins

Exotoxins

Are released during death, mechanical damage and lysis of bacteria but also during bacterial growth and division. (bmglabtech.com)

Secreted as part of the cell’s metabolism

Does not have any enzymatic activities

Most activities are enzymatic in nature

Immune response is weaker

Immune response is stronger

Made of lipopolysaccharides

Made of proteins

Moderately toxic

Highly toxic

Cannot be made into toxoids

Can be made into toxoids

Highly resistant to heat

Can be killed by boiling

(A toxoid is a chemically modified toxin from a pathogenic microorganism, which is no longer toxic but is still antigenic and can be used as a vaccine (Oxford languages).)

There is so much to study about bacteria, however since we at HypoAir mainly focus on air quality, we’ll try to limit this post to the toxins that can be transmitted through the air.  

Endotoxins (source: buildequinox.com, manufacturer of the CERV Energy Recovery Ventilator in Urbana, Illinois):

  • Are pyrogens, that is, they often cause a pyrogenic reaction (fever).
  • Cause fatigue, a common characteristic of sick building syndrome. 
  • Don’t produce immunity, but only a temporary resistance known as “Monday fever”. Workers in industries with significant endotoxin levels have been found to be most afflicted on Monday, with reduced effects through the week. Endotoxin resistance is lost over the weekend, with the illness beginning anew the following Monday [5]
  • Are “adjuvant”, meaning that they can amplify the effects of other harmful substances. 
  • Are associated with sepsis, an extreme immune response by the body that often ends in death.  
  • The presence of pets in indoor spaces can represent an important source of air contamination and can be linked with the level of indoor endotoxins. The presence of dogs and cats can be the main predictors of endotoxin levels in house dust [1, 4-7]. Other predictors are the presence of vermin, such as mice, and infrequent cleaning, which indicates poor hygienic conditions in the home [1]. Storage of organic household waste indoors also increases bacterial contamination in the indoor environment [1]. (intechopen.com)

How can we reduce exposure to endotoxins?

  • Reduce Dust: According to EMLab, a commercial IAQ laboratory in North America, “ Endotoxin exposures are mainly through the air.”  “Endotoxins do not float freely, but instead are attracted to dust particles. Reduction of dust is essential for controlling endotoxin levels. Dust reduction requires both fresh air filtration and filtered air recirculation. Continuous, low flow fresh air ventilation systems without recirculation do not effectively manage indoor particulates. Endotoxin levels and dust levels are not strongly correlated indicating that they come from independent sources. A single dust particle in the 2 to 10 micron range has sufficient surface area to hold a million or more endotoxin molecules (approximately 0.1ng of endotoxin). Therefore, reduction of dust is important regardless of whether one lives in a dusty or relatively dust-free environment.” (this and following points from buildequinox.com).
  • Removal of food sources: “Coupled with proper ventilation is reduction of source generation of endotoxins. In the home environment, it is clear that kitchens are one source of endotoxin generation. Removal of food wastes and standing dishwater will reduce bacterial growth with subsequent production of endotoxins. Even a bowl of standing water will grow bacteria in a home. Bacteria and nutrients are ubiquitous indoors and outdoors, and they will land in water or moist regions where bacterial growth will occur.” Kitchens have the highest level of endotoxins, followed by living rooms and bedrooms.
  • Avoid use of misting humidifiers: “Cold temperature (misting) humidifiers are strongly linked to high endotoxin levels. Vaporizing humidifiers that heat water to boiling have not been found to produce high levels of endotoxins.” An alternative method for achieving sanitized, cold temperature humidification in a home is through plant transpiration. Plants can reduce toxins in homes [12]. The plant-root matrix releases sanitized water into the air (assuming proper plant care that does not form a wet mass promoting fungal and bacterial growth).

Exotoxins are (from textbookofbacteriology.net unless otherwise noted)

  • part of a defensive system of bacteria to avoid capture and killing by leucocytes (part of our body’s immune system). (sciencedirect.com)
  • Produced by both Gram-negative and Gram-positive bacteria 
  • More highly poisonous by mass than endotoxins, strychnine, or snake venom 
  • Can be “super-antigenic” or cause stimulation to the immune system 
  • are often encoded by mobile genetic elements, including bacteriophage (phage). Phage can transfer genetic information to the bacteria they infect. (study)
  • Can produce illness even when the microbes that produced them have been killed. (skybrary.aero)

What are the sources of exotoxins? (from intechopen.com)

  • Actinobacteria (especially Streptomycetes), Bacillus species and various other bacteria grow in moist building materials together with fungi. Elements from bacterial structures released in air include bacterial cells, bacterial spores, peptidoglycans, microbial volatile organic compounds, exotoxins, and other bacteria growing metabolites.
  • Gram-positive bacteria with exo- and endospores like Streptomyces and Bacillus can grow on moist building materials. Their spores are very resistant and can survive even if the air humidity is low.
  • Humans are an important source of indoor bacteria. The upmost layer of the normal human skin is continuously renewed, and skin scales containing bacteria are shed into the environment. Bacteria in the respiratory airways are eliminated through Pflügge droplets while talking, coughing, or sneezing. The level of air contamination is dependent on the number of persons inside a room and the efficiency of the ventilation system (natural or artificial ventilation). Bacteria that can be identified in indoor air are micrococci, staphylococci, streptococci, and corynebacteria.

How can we reduce exotoxin exposure?

  • Maintain your home so that there are no active leaks and humidity stays between 40-60%.  This will reduce actinobacteria that produce exotoxins.
  • Practice good hygiene by covering your mouth and nose while coughing or sneezing.  This reduces the amount of small particles in the air that can contain bacteria and exotoxins.  Dispose of tissues in the trash and wash hands with soap and water. 
  • According to the WHO, if exposure to the toxin via aerosol inhalation is suspected, additional exposure to the patient and others must be prevented. The patient's clothing must be removed and stored in plastic bags until it can be washed thoroughly with soap and water. The patient should shower and be decontaminated immediately. 
  • Most exotoxins can be destroyed by heating, (wikidoc.org), so eating thoroughly cooked food often eliminates the danger of ingesting the exotoxin. The WHO recommends these five strategies in food safety:
    • keep clean
    • separate raw and cooked
    • cook thoroughly
    • keep food at safe temperatures
    • use safe water and raw materials.

Use of a HEPA filter can reduce aerosols and fine particles containing bacteria, endotoxins and exotoxins, although some of the smaller phages may slip through.  This is where a healthy immune system and abstaining from smoking pick up.  Cigarette smoking is a substantial risk factor for important bacterial and viral infections. For example, smokers incur a 2- to 4-fold increased risk of invasive pneumococcal disease. (2004 study).  In addition, exposure to cigarette smoke causes MRSA bacteria (just one bacteria studied) to become even more resistant to killing by the immune system. (UCSanDiego Health News)  Of course, smoking through a dirty water pipe (bong) is inviting disaster!  Here are the details (mooselabs.us):

Bacteria, endotoxins and exotoxins are all around us (and even in us), but with good judgment and  precautions, you can avoid being one of the infection statistics!

Photo by CDC on Unsplash