Americans spend approximately 90% of their time indoors, and as winter tightens its grip, we may spend even more time indoors, with our windows sealed against the cold.

This creates an important challenge — maintaining healthy indoor air quality. According to the American Lung Association, indoor air can contain two to five times more pollutants than outdoor air — and in some cases, indoor air pollution levels can be up to 100 times higher than outdoor air.

With a few smart changes, you can turn your home from a pollution trap into a clean-air oasis. The air in our homes tells a complex story of modern living. Every product we bring inside, every meal we cook, and even every breath we take contributes to a complex chemical environment that affects our health and the well-being of our planet. Volatile organic compounds, carbon monoxide, particulates, mold and radon are the main pollutants of concern.

Walk into any newly furnished room or recently painted space and breathe in that distinctive “new” smell. What you’re actually detecting are volatile organic compounds, or VOCs, chemicals that readily evaporate into the air. These compounds emerge from countless sources: preservatives in pressed wood furniture, solvents in paints and varnishes, surfactants in cleaning products, and even the scents in air “fresheners” that are designed to mask other odors.

Unlike the subtle presence of VOCs, carbon monoxide presents a more immediate danger. This odorless, colorless gas comes from fuel-burning appliances. Even a properly functioning wood, coal, oil, gas stove, or furnace produces some CO; malfunctioning equipment can quickly create dangerous levels. This is where the connection between maintenance, safety, and sustainability becomes clear — well maintained equipment reduces CO pollution and operates more efficiently, shrinking energy consumption.

The dancing dust motes in a sunbeam represent only the largest visible portion of particulate matter in our homes. The most concerning particles are actually the ones we can’t see — those smaller than 2.5 micrometers that can penetrate deep into our lungs, past our natural defenses that line our respiratory tracts. These microscopic particles arise from cooking (especially frying and broiling), fireplaces, candles and outdoor pollution, such as vehicle emissions, that make it indoors.

The environmental impact of particulate matter extends beyond our homes. Many of the same activities that generate indoor particles also contribute to outdoor air pollution and climate change. For instance, wood-burning fireplaces have a hefty environmental cost to our forests, while electric heating alternatives can be powered by sunshine that would otherwise simply reflect off our roofs.

Mold represents nature’s decomposition process gone indoors. These fungi play a vital role in breaking down organic matter in the natural world. Inside our homes, mold indicates a building science problem. When we find mold, it tells us we have a moisture, ventilation, or building envelope problem — a signal that we may be wasting energy and endangering our family’s health.

The connection to sustainability runs deep here. The same water intrusion that enables mold growth often compromises insulation effectiveness and structural integrity, leading to increased energy consumption and reduced building longevity. Addressing moisture issues properly serves both environmental and health goals.

Rising from the decay of uranium in the earth itself, radon reminds us that not all pollution comes from human activity. This naturally occurring radioactive gas seeps into buildings, accumulating in well-sealed spaces below ground. Modern buildings balance radon mitigation with energy efficiency, often through carefully designed ventilation systems that maintain indoor air quality while minimizing heat loss.

The relationship between these pollutants and sustainable building practices highlights a crucial truth: healthy buildings must be both energy-efficient and well ventilated. The tighter we seal our homes to conserve energy, the more mindful we must be of what we bring into them. The goal is to create healthful spaces for shelter while treading lightly on the planet — a result achieved through wise choices in both construction and daily living.

Your journey to better indoor air quality starts with a simple step — perhaps with a low-cost hygrometer to discover your home’s humidity levels — that leads to more steps — like better ventilation during showers or cooking — to transform your indoor environment into a comfortable and healthy haven of clean air.

You’ll likely notice better sleep, easier breathing, and maybe even lower energy bills as you tackle obvious pollution sources and fine-tune your ventilation. The best part? Every step helps your family breathe easier and contributes to cleaner air for everyone.

Peggy Siegle and Fred Horch are principals of Sustainable Practice. To receive expert action guides to help your household and organizations become superbly sustainable, visit SustainablePractice.Life and subscribe for free to “One Step This Week.”