Michael Feldstein on Cleaner Indoor Air and the Limits of Air Filters

Chris Williamson brings household products to the table and asks Michael Feldstein how he became interested in indoor air. Feldstein says that when he travels he pays attention to the bedroom first: it is where he spends hours and has the least control over the surroundings.

Feldstein worked in disaster restoration after floods, fires and hurricanes, including removing mold from damaged homes. He says the job involved both taking contaminated material out of a building and cleaning the air while work was under way.

His turning point came after the 2016 Fort McMurray wildfire in Alberta. Homes outside the fire itself had heavy smoke damage. His crew cleaned one house, but a week later its occupant called because the air seemed bad again.

Testing inside alone would have missed the context, Feldstein says: outdoor air remained contaminated, and it was getting back inside. The team cleaned the house again and left industrial air scrubbers running to maintain the improvement.

He then tried smaller consumer air cleaners in the same setting and says they did not perform well in his test. He wanted the capacity of the restoration equipment in something quiet and attractive enough to live with. That became the starting point for Jaspr.

Asked how much air quality matters alongside exercise and sleep, Feldstein says breathing is continuous and largely invisible. He uses the volume of air people breathe to explain why he thinks indoor conditions deserve attention as well as food and water.

He calls air 'sleep fuel' and places a clean bedroom high on his list. This is his view of how to think about recovery: improve the surroundings during the hours when a person is sleeping there, then consider the rest of the house.

Williamson asks about both immediate performance and longer-term health. Feldstein cites research on decision-making and sports performance to argue that environmental conditions can matter before people consciously notice discomfort.

Williamson says he spent more than two years trying to recover his health after problems he associates with air quality in his home. He says he had already tried another filter before Feldstein brought Jaspr devices to his house.

Feldstein is careful to call his company's next example a community-led experiment. About 150 volunteers who had not previously filtered their air used wearable sleep trackers, with weeks using and not using the devices. He reports an average increase of roughly 25 minutes of sleep during use. Williamson notes that this was not a randomized laboratory trial.

Participants shared their data with the company, and Feldstein says he wants a larger, more formal sleep study. He also recounts customers' personal reports about allergies and snoring; the conversation presents these as experiences people shared with his business.

His team sometimes delivers devices locally and measures air before and after, he says. The discussion moves to pollen: particles brought into a home can remain on furnishings, whereas hard, sealed surfaces are easier to clean during restoration work.

When Williamson asks what makes indoor air worse, Feldstein starts with shoes carrying material from outside. He prefers removing shoes at the door. He also points to cooking, especially high-heat cooking, as something that can generate particles and other emissions.

His practical suggestion is to use the range hood while cooking. He groups cooking with sprays, plug-in fragrances, candles and incense as sources to consider when thinking about what is released into an enclosed space.

Feldstein compares outdoor air to a flowing river and indoor air to a pond: the enclosed space can accumulate material if it is not exchanged or cleaned. He says people should think about both what they introduce and how air moves.

Williamson asks where indoor air actually comes from. Feldstein lists the openings and leaks around a building, including doors, windows, vents and the building envelope. The air indoors is connected to what happens outside, as well as what happens inside.

The conversation turns to carbon dioxide. People exhale CO2, so its concentration can rise in occupied, poorly ventilated rooms. Feldstein uses it as an example of why bringing in fresh air is a different problem from filtering particles.

Williamson describes long recordings with several people in a studio where opening the door can introduce noise and light. He and Feldstein discuss measuring the room and making ventilation part of a studio's design rather than assuming the space is comfortable because it feels cool.

Williamson raises a concern: health advice can become one more exhausting list of things to monitor. Feldstein says he wants changes in the environment to make daily life easier, and describes starting with the spaces where people spend the most time.

He puts air, water and light among his priorities, while acknowledging that people have different budgets and tolerances for additional equipment. His argument is to start with a few changes instead of trying to optimize every room at once.

Asked about different regions, Feldstein says local conditions vary: humidity, building design, leaks, dust and wildfire smoke can change the problems a household faces. He draws on places where he has worked, including Florida, Austin and the Southwest.

He discusses air-conditioning equipment and moisture in attics, arguing that a leak or condensation problem must be addressed rather than merely covered up. He also describes places where he personally enjoys the outdoor air, including the Costa Rican rainforest.

Williamson shows the guest ordinary products including sprays and fragrances. Feldstein says combustion produces emissions indoors and that he personally tries to minimize scented sprays, especially in enclosed rooms.

Feldstein says a particle sensor on his product can make people aware of changes during activities such as using aerosol products. He suggests using products outside where possible or using a bathroom exhaust fan when they are used indoors.

Discussing plug-in scents and odor sprays, Feldstein distinguishes covering an odor from removing its source. He says that in his own home he is sensitive to perfume and prefers less added fragrance. Williamson asks how people can clean an object rather than simply scent it.

For a smelly item, Feldstein suggests washing it or airing it outside rather than relying solely on fragrance. He also asks people to think about where a sprayed product ends up, using food coloring in water as an analogy for distribution through a space.

On candles, Feldstein says he personally uses them but considers not burning one the lower-emission option. He prefers beeswax candles and describes extinguishing them outside to keep the visible smoke at the end out of the room.

Williamson asks who may be especially susceptible to air problems. Feldstein mentions infants and older people, then tells a story about moving a diaper pail out of his child's room because of the odor. His broader point is to consider sources near the place a person sleeps.

For inexpensive changes, Feldstein names removing shoes, using the kitchen range hood and running the bathroom exhaust fan after a shower. He says moisture left in an enclosed bathroom can contribute to problems over time, so the fan has a purpose beyond removing odors.

He also suggests keeping a dryer vent and lint trap clean and being aware of the products used in the home. Where conditions allow, opening windows is another way to exchange air; he notes the European habit of airing rooms regularly.

Williamson asks why air conditioning does not automatically solve the problem. Feldstein says many residential heating and cooling systems primarily regulate temperature and may run only when a thermostat calls for them, so people should understand what their particular system actually does.

He says his early attempt to build a filter into a heating and cooling system ran into airflow and noise constraints. A denser filter can increase resistance, so compatibility with the system matters. His longer-term ambition is equipment designed around both comfort and air quality.

Feldstein says that paying attention to humidity and air measurements changed how he notices his surroundings. He compares that awareness with people's ability to estimate temperature after years of checking forecasts, and imagines weather reports that also highlight air quality.

When viewing a home, Williamson asks what would cause Feldstein to investigate further. Feldstein says an ordinary inspection has a defined scope and may not cover all environmental concerns. He recommends paying attention to moisture, odors and the scope of any inspection.

They discuss mold testing. Feldstein says some remediation work is expensive and that growth in the market has created room for alarm. Williamson asks how a buyer can distinguish a reliable inspector from someone whose incentives lead to unnecessary work.

Feldstein argues that a simple positive result does not answer every question: the kind of material, its amount, location and circumstances need interpretation. He also acknowledges how difficult it can be to choose a contractor. Williamson says he asked friends for repeated recommendations.

Williamson turns to Jaspr, the company Feldstein founded and a product promoted in the episode. Feldstein calls its device an air scrubber, drawing a comparison with the industrial equipment he used during restoration. He describes a larger filter, a metal body and a sensor that changes fan speed.

The founder says he wanted an appliance that could move air quietly while fitting into a home. His wife objected to the appearance and sound of the industrial machine he brought home, so appearance and noise became part of the design brief.

Feldstein says the company initially found customers among Ontario dental practices during the pandemic. He recalls advising buyers on room dimensions and airflow, and says a high-speed mode developed for that setting remained in the consumer product.

Williamson says he has tried several machines and now uses Jaspr devices around his house. Feldstein describes his company's own comparisons with another machine. Asked where a person should start, he says he would put one in the bedroom, where it can run while someone sleeps.

For a constrained budget, Feldstein mentions the Corsi–Rosenthal box, a do-it-yourself fan and filter assembly. He also discusses filter replacement and the service arrangement for his company's machine, explaining why he designed it to be easy to maintain.

His next priority would be another room where people spend a lot of time, such as a living room or home office. He says placement should allow the device to draw air freely. Williamson asks how this applies when the kitchen and living area share one space.

Feldstein outlines proposed research in workplaces and schools, including comparing outcomes across groups using air cleaners. He describes a school in Austin as a place where he hopes to study several environmental changes together. These are plans and questions he wants to investigate.

Williamson closes by explaining why the subject is personal after his own health difficulties. He says he does not want the conversation to make people afraid, and hopes listeners consider steps they can take within their means. Feldstein says his company is also interested in future heating and cooling products.