BREATHING HEALTHY AIR

Quick takes

• Air quality impacts health outcomes in many ways;

• Indoor air reflects outdoor air, plus the toxins related to indoor objects;

• Opening windows improves the quality of indoor air unless outdoor air is (temporarily) problematic;

• Addressing outdoor air quality requires better laws and regulations;

• Addressing indoor air quality involves making good choices re: appliances and furnishings;

• We can improve the air we breathe by using an air purifier – at least when outdoor air quality is poor;

• I recommend keeping track of indoor air quality with an air quality monitor, or keeping track of outdoor air quality using the weather app on your phone, or a website such as airnow.gov or Purple Air. The iPhone weather app in the uS and Canada lists the overall air quality score as well as the source of most of the pollution.

• Air purifiers improve the quality of indoor air and have a number of demonstrated positive health effects.

Favorite finds

• Measuring PM2.5, PM10, VOCs:

  Some options include:

  • Atmotube Pro

  • Foobot

  • Ikea’s Vindstyrka

• Purify air

  • Air Doctor

  • Austin Air

  • Clean Air Kits

  • Corsi-Rosenthal box

• Learning about healthier alternatives for cleaning products, consumer goods, etc. for the home: I Read Labels for You

• Measuring mold toxins:

  • Here are three companies that can be used without a mold inspector: Mycometrics, Envirobiomics, Lis Biotech. Functional medicine physicians usually recommend the “dust-based” tests (not air sampling)

• Humidity: Ikea Vindstyrka

• I am most familiar with the Aranet 4; The following are some less expensive options discussed online: Inkbird IAM-T1, Vitalight Mini CO2 detector, and Acrimax Multi-Function CO2 detector

• I use the CO2 detectors to decide when to wear a mask in certain public situations such as conferences. More CO2 in the air means that we are breathing a larger proportion of exhaled air. Also viruses such as SARS-COV2 survive better in high CO2 conditions.

Deep Dive

Outdoor air is often more polluted than we think, and forms the basis for the air we breathe indoors. Our choice of appliances and household furnishings may further contribute to poor indoor air quality.

There are many ways to improve the quality of the air indoors where individuals have some level of direct control. The second part of this deep dive will outline a possible strategy for mitigation.

OUTDOOR AIR

1. Particulate Matter (PM)

• PM2.5 (fine particles ≤ 2.5 µm) and PM10 (coarse particles ≤ 10 µm)

• Sources: Vehicle emissions, industrial processes, burning fossil fuels, dust storms

• Mitigation: home air purifiers

• Health Effects:

  • Penetrates deep into lungs and bloodstream

  • Causes respiratory diseases (asthma, bronchitis, lung cancer)

  • Increases risk of cardiovascular diseases (heart attacks, stroke)

  • Results in premature death, especially in vulnerable populations

2. Carbon Monoxide (CO)

• Sources: Incomplete combustion of fossil fuels, vehicle emissions, household heating

• Mitigation: directed at indoor sources: maintain and service fuel-burning appliances properly; ventilate, use carbon monoxide detectors

• Health Effects:

  • Reduces oxygen delivery to organs

  • Causes headaches, dizziness, confusion, and even death at high levels

  • Especially dangerous for people with heart conditions

3. Nitrogen Oxides (NOx)

• Includes: Nitric oxide (NO) and nitrogen dioxide (NO₂)

• Sources: Vehicle exhaust, industrial processes, power plants

• Mitigation: None at the individual level; we need stricter regulation and emission control

• Health Effects:

  • Causes lung irritation, reduced lung function, and respiratory infections

  • Contributes to smog and acid rain, worsening environmental conditions

4. Sulfur Dioxide (SO₂)

• Sources: Coal and oil burning, industrial emissions, volcanoes

• Mitigation: None at the individual level, but choosing renewable energy sources helps, as do stricter regulation and emission control

• Health Effects:

  • Irritates respiratory system, leading to coughing and shortness of breath

  • Worsens asthma and other lung diseases

  • Contributes to acid rain, damaging ecosystems

5. Ozone (O₃) – Ground-level Ozone (Smog)

• Sources: Formed by the reaction of NOx and volatile organic compounds (VOCs) in sunlight

• Mitigation: None at the individual level, we need stricter regulation and emission control

• Health Effects:

  • Causes throat irritation, coughing, and chest pain

  • Triggers asthma attacks and reduces lung function

  • Long-term exposure can lead to lung damage

6. Volatile Organic Compounds (VOCs)

• Sources: Vehicle emissions, industrial processes, solvents, household products, this also includes tire wear particles

• Mitigation: Use low VOC paints, stricter regulation and emission control, ventilate the home since many come from household sources; air purifier containing sufficient carbon filters.

• Health Effects:

  • Some VOCs are carcinogenic (e.g., benzene)

  • Contribute to ground-level ozone and smog formation

  • Cause headaches, nausea, and eye irritation

7. Lead (Pb) and other heavy metals

• Sources: Industrial emissions, leaded gasoline (historically), battery manufacturing

• Mitigation: pay attention to heavy metals in food and household items; measuring and helping the body reduce lead burden may be possible

• Health Effects for lead:

  • Affects nervous system, brain development (especially in children)

  • Causes cardiovascular and kidney diseases

  • Long-term exposure leads to cognitive impairments

• Health Effects for lead:

  • Everything from cancer to metabolic dysregulation, osteoporosis, neurotoxicity, and more.

8. Ammonia (NH₃)

• Sources: Agriculture (fertilizers, animal waste), industrial emissions

• Mitigation: avoid ammonia cleaners

• Health Effects:

  • Causes respiratory irritation

  • Contributes to PM2.5 formation, worsening air quality

WHAT DOES INDOOR AIR ADD TO THIS?

Indoor environments contribute further pollutants to indoor air. These include:

1. Volatile Organic Compounds (VOCs)

• Sources:

  • Building materials (paint, flooring, adhesives, insulation)

  • Furniture & carpets (especially new ones that off-gas chemicals like formaldehyde)

  • Cleaning products (disinfectants, air fresheners, scented candles)

  • Plastics & electronics (flame retardants, plasticizers)

• Health Effects:

  • Eye/nose/throat irritation

  • Headaches, dizziness, nausea

  • Long-term exposure: Increased risk of cancer, liver/kidney damage

2. Mold & Mildew

• Sources:

  • Damp areas (bathrooms, kitchens, basements, around windows)

  • Leaky plumbing, appliances, roofs, or other water damage

  • HVAC systems with trapped moisture

• Health Effects:

  • Allergies (sneezing, coughing, watery eyes)

  • Asthma & respiratory infections

  • Toxic mold (e.g., Stachybotrys or "black mold") can cause severe health issues, including immune, liver, kidneys, brain, cancer

  • While both indoor and outdoor molds can affect health, indoor mold is often considered more hazardous due to higher exposure levels and the potential for sustained contact in enclosed spaces.

3. Gas Stoves & Combustion Appliances

• Pollutants Released:

  • Nitrogen dioxide (NO₂) → irritates lungs, worsens asthma

  • Carbon monoxide (CO) → reduces oxygen delivery to the body

  • Formaldehyde & fine particulate matter (PM2.5) → increases respiratory disease risk

• Solutions:

  • Use ventilation (range hood or open window)

  • Switch to electric or induction cooking if desired

4. Dust, Pet Dander, & Microplastics

• Sources:

  • Fabric furniture, bedding, carpets trap dust & allergens

  • Shedding from synthetic materials contributes to microplastic pollution

• Health Effects:

  • Inhalation of dust & microplastics may lead to potential lung inflammation, cardiovascular, or brain impacts

  • Allergic reactions & asthma triggers

5. Carbon dioxide

• Sources:

  • Exhaled air from human inhabitants. Rises fast when there are many people gathered in a small space, or when the house is tightly sealed.

• Health Effects:

  • High CO2 causes cognitive impairment in the short term

  • Certain viruses, including SARS-COV2 survive better at high CO2 levels, explaining why long airplane trips are more likely to lead to infection.

HOW TO IMPROVE INDOOR AIR

1. Increase Ventilation (When Outdoor Air is Clean)

• Open windows and doors when outdoor air quality is good to dilute indoor pollutants.

• Use window fans or exhaust fans to push indoor air out and bring fresh air in.

• Consider mechanical ventilation systems, such as heat recovery ventilators (HRVs) or energy recovery ventilators (ERVs), to maintain fresh air exchange without excessive energy loss.

When outdoor air is polluted (such as during wildfires or high PM2.5 levels), keep windows closed and rely on filtered air circulation. In one urban fire situation, I found I needed my Air Doctor purifier in the same room, and the PM2.5 level dropped after about 30 minutes of operation on the highest level. I was tracking PM2.5 levels using a Foobot air quality sensor.

2. Control Humidity and Prevent Mold Growth

• Maintain indoor humidity between 30–50% to discourage mold and dust mites.

• Use dehumidifiers in damp areas.

• Fix leaks and ensure good drainage around the home to prevent moisture buildup.

• Any building materials that stay wet longer than 5-7 days are arguably compromised and should be removed.

• Regularly clean air conditioning units, HVAC ducts, and bathroom fans to prevent mold growth.

3. Reduce Indoor Pollution Sources

• Consider switching from gas stoves to electric or induction cooktops to reduce nitrogen dioxide (NO₂) and PM2.5 emissions;

• If using a gas stove, always use a high-quality range hood that vents outdoors;

• Avoid burning wood in fireplaces, candles, and incense, as they release fine particles and volatile organic compounds (VOCs);

• Choose non-toxic cleaning products, furniture, and paints that emit fewer VOCs.

• Store paints, solvents, and pesticides in sealed containers outside the living space.

4. Use Indoor Plants (Limited Air Cleaning but Offer Other Benefits)

• Certain houseplants, such as snake plants, peace lilies, and pothos, help reduce carbon dioxide and VOCs slightly but are not as effective as mechanical filtration;

• However plants can improve perceived air quality and mental well-being by increasing oxygen levels and reducing stress.

Overwatering plants can encourage mold growth, so it is important to keep humidity under control.

5. Improve Filtration in HVAC Systems

• Upgrade to MERV 13 or higher air filters in HVAC systems to trap smaller particles, including PM2.5.

• Change filters regularly, every two to three months or sooner in high-pollution areas.

• Consider duct cleaning services if there is suspected dust buildup or mold contamination.

6. Control Dust and Allergens

• Vacuum frequently with a HEPA-filter vacuum to remove dust, pet dander, and microplastics.

• Dust surfaces with a damp cloth instead of dry dusting to trap particles.

• Wash bedding weekly in hot water to eliminate dust mites.

• Remove shoes at the door to prevent bringing in outdoor pollutants.

7. Reduce Microplastics in Air and Dust

• Choose natural fiber rugs, curtains, and bedding instead of synthetic materials.

• Use hardwood, tile, or laminate flooring instead of carpets, which trap dust and microplastics.

• Ventilate well when using plastic-based products, such as during 3D printing or when new synthetic furniture is off-gassing.

8. Monitor Air Quality and Take Action

• Use an indoor air quality monitor to measure PM2.5, VOCs, carbon dioxide (CO₂), and humidity levels. As mentioned, I am familiar with the Foobot. There are inexpensive options through Ikea and other online options.

• Consider an air purifier that targets the main issues; even a small decrease in PM2.5 particles can yield significant health benefits when used 24 hours a day.

• If CO₂ levels rise above 800–1000 ppm, increase ventilation to bring in fresh air. In a crowded space, consider wearing a respirator to avoid catching pathogens. The most reliable CO2 monitor is the Aranet 4.

  
  

AIR PURIFIERS

I now routinely recommend air purifiers. The problem seems to be which one to choose. There are two main considerations:

• what do they filter out?

• how much air do they move hourly?

Particle type and size:

• What size particle is being removed (it should be at least 0.3 microns, but some filters go down to 0.03 microns)

• How much VOC is being removed? To do so, a purifier requires a filter containing a significant amount of charcoal, and that is uncommon.

Clean air delivery rate (CADR):

• The CADR is the amount of air that goes through the filter in one hour. This tells you what size room you can use your filter in, depending on the use. For example, in an operating room, the aim is 20 air changes per hour (ACH), and they want to remove both pathogens and tiny particles. This is the highest standard: a home does not need so many ACHs.

• For COVID safety, a rule of thumb is to use a CADR that is only a little lower than the room size in square feet. In that particular case, you also need a filter that goes down to small particles. A MERV 13 filter is sufficient.

I am most familiar with the following options:
IQ Air: filters particles down to 0.03 microns, has a good amount of charcoal, but expensive and can be loud

Austin Air: the best at removing VOCs because it has a lot of charcoal; only filters particles down to 0.3 microns

Air Doctor: filters particles down to 0.03 microns, good with viruses but not so great with VOCs as it only has a small amount of charcoal. Quiet and has an automatic setting where it adjusts the CADR based on the level of particles detected.

Air purifiers can be expensive, not only for the initial purchase, but also for the yearly purchase of replacement filters. The least expensive but very effective option is the do-it-yourself Corsi-Rosenthal box. The company Clean Air Kits also makes affordable air purifiers. All links are in the Favorite Finds section.