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Starvard University · Healthy Home 101: Mold, Lead, Radon, and Air
You will find and fix the hidden hazards in your home that quietly harm your family's health. Built on EPA and HUD guidance, this course works room by room: moisture and mold, lead, radon, alarms, air, pests, and safe storage, ending with a walk through checklist for your own home.
Hello, my name is Finn, and I'm going to help you understand this course.
Here it is, explained like you are 10:
Your house can look fine and still hide things that make people sick, like damp mold, old lead paint dust, or a gas called radon that you cannot see or smell. This course teaches you to hunt for those hidden problems one by one, test for the ones you cannot see, and fix the small ones safely yourself. For the dangerous jobs, it teaches you when to stop and call a trained expert.
HUD sums up a healthy home in seven words: keep it dry, clean, safe, pest free, contaminant free, ventilated, and maintained. Those seven principles run through every lesson here. Most home hazards are not mysteries. They follow water, dust, and air, so if you learn to control moisture, clean in ways that keep dust down, and bring in fresh air, you have handled the largest part of the work.
The EPA supplies the numbers that matter. A mold patch under about 10 square feet is usually a do it yourself cleanup, and bigger areas need more care or a professional. Radon should be fixed at 4 pCi/L and considered for fixing between 2 and 4. Lead paint in homes built before 1978 is never a do it yourself removal job. The course ends with a walk through checklist so you can grade your own home and make a short fix list.
The whole course in brief
What you will be able to do after this course
The ten lessons
Lesson 1
A healthy home is not a perfect home. It is a home kept by seven habits, set out by the U.S. Department of Housing and Urban Development: keep it dry, clean, safe, pest free, contaminant free, well ventilated, and well maintained. HUD's healthy homes work rests on a simple finding: many illnesses and injuries tied to housing are preventable, and the prevention is usually ordinary upkeep done on time, not expensive renovation. Those seven words are the map for this whole course.
Dry comes first, because water starts most of the trouble in later lessons. A dry home gives mold, mites, roaches, and rodents far less to live on. Clean means controlling dust and clutter and using wet cleaning methods, so contaminants are removed instead of stirred into the air. Safe means storing poisons out of children's reach, securing loose rugs, and keeping smoke and carbon monoxide alarms working. Pest free and contaminant free mean keeping insects and mice out without spreading poisons, and reducing lead, radon, asbestos, and chemical exposures where they hide.
Ventilated and maintained finish the list. Ventilation brings fresh air in and pushes moisture and pollutants out, especially from kitchens and bathrooms. Maintained means inspecting, cleaning, and repairing routinely, so a small leak is fixed while it is still small. Hold those seven words as a checklist and every lesson that follows has a home: mold belongs to dry, lead belongs to contaminant free, alarms belong to safe, and your final walk through in Lesson 10 will grade your home against all seven.
Lesson 2
Mold needs one thing above all: moisture. The EPA's brief guide to mold puts it in one line: the key to mold control is moisture control. Spores drift through every home and settle everywhere, but they only grow where surfaces stay wet. So the order of work is always the same. Find and fix the water source first, a leak, a dripping pipe, condensation, or damp ground, then clean the mold. Clean without fixing the water and, as the EPA warns, the mold problem will most likely come back.
Speed matters after water gets in. The EPA advises drying water damaged areas and items within 24 to 48 hours to prevent mold growth, and keeping indoor humidity below 60 percent, ideally between 30 and 50 percent, measured with an inexpensive humidity meter. Run bathroom fans or open windows when showering, vent dryers and stoves outside where possible, slope soil away from the foundation, and keep gutters and air conditioner drip pans clean and flowing. Those dry habits do more than any spray bottle.
For cleanup, size decides who does the job. The EPA says that if the moldy area is less than about 10 square feet, roughly a 3 foot by 3 foot patch, you can usually handle it yourself: scrub mold off hard surfaces with detergent and water, dry completely, wear gloves, goggles, and an N-95 respirator, and never paint or caulk over moldy surfaces. Porous materials such as ceiling tiles and carpet may have to be thrown away if they become moldy. Bigger areas, mold in the heating and cooling system, or damage from sewage or contaminated water call for an experienced professional, and anyone with health concerns should consult a health professional before starting.
Lesson 3
Lead hides in two everyday places: old paint and drinking water. The federal government banned lead based paint for homes in 1978, so a home built before 1978 is more likely to have it, and the danger is mostly dust: chips and dust from peeling or friction worn paint on windows, doors, and stairs, which young children meet by crawling and putting hands and toys in their mouths. The EPA is clear that young children are the most vulnerable. Paint in good condition is usually not a problem, so the first defense is keeping paint intact and wet cleaning floors, sills, and door jambs weekly to keep dust down.
Here is the hard safety line of this course. Lead paint work in pre-1978 homes is EPA RRP certified professional territory, never do it yourself removal. The EPA says plainly: avoid do it yourself removal of lead based paint, and hire a lead safe certified contractor trained in lead safe work practices for renovation, repair, and painting work. Federal law requires firms paid to disturb paint in pre-1978 housing to be lead safe certified. The same caution covers asbestos, which hides in some older insulation, floor tiles, roofing, and textured coatings: do not disturb it. Material in good condition left alone is the safe state, and any removal or repair belongs to licensed asbestos professionals.
Lead in water is invisible too: you cannot see, taste, or smell it, and testing is the only way to know. It enters as plumbing containing lead corrodes, most often from lead pipes and lead service lines, which are more likely in older cities and homes built before 1986. The EPA's steps are practical: use only cold water for drinking, cooking, and baby formula, because hot water draws more lead from pipes; clean the faucet aerator where particles collect; use a filter certified to remove lead if you use one, and replace its cartridge on schedule. And remember: boiling water does not remove lead.
Lesson 4
Radon is a naturally occurring radioactive gas that seeps from soil and rock into homes through foundation cracks and openings. You cannot see it or smell it, so, as the EPA repeats, testing is the only way to know your level of exposure. The EPA identifies radon as the second leading cause of lung cancer overall, and the number one cause among people who have never smoked, responsible for about 21,000 lung cancer deaths every year in its assessment. Every home can have a radon problem, which is why the EPA says all homes should be tested.
The test itself is cheap and undramatic. Short term test kits sit in the lowest lived in part of the home for a few days and are mailed to a lab, and longer tests give a better picture across seasons. Results come back in picocuries per liter, written pCi/L. Two reference points from the EPA help you read the number: the average indoor radon level is about 1.3 pCi/L, and the average outdoor level is about 0.4 pCi/L. There is no known completely safe level, so lower is always better, but the EPA gives clear action lines so you are not left guessing.
Here are those lines, and they are the numbers to remember from this lesson. Fix your home at 4 pCi/L or higher. Consider fixing it between 2 and 4 pCi/L. Reducing levels below 2 pCi/L is difficult, which is why the action lines sit where they do. Fixing usually means a mitigation system, most often a vent pipe and fan that draw soil gas from under the home and release it outside, installed by a qualified radon mitigator. After any fix, test again to confirm the level fell. If you smoke, the combined risk is much higher, and stopping smoking is part of the radon fix too.
Lesson 5
Carbon monoxide, called CO, is the alarm lesson's invisible half. The EPA describes it as an odorless, colorless, and toxic gas that can kill before you are aware it is in your home. It comes from things that burn fuel: furnaces, water heaters, gas stoves, fireplaces, wood stoves, and generators. Keep fuel burning appliances properly adjusted and inspected by a trained professional every year, use an exhaust fan vented outdoors over a gas stove, and never use a portable generator inside a home, garage, crawlspace, or shed. Deadly levels can build up quickly and linger for hours.
Alarms turn an invisible risk into a loud one. For carbon monoxide, the Consumer Product Safety Commission guidance quoted by the EPA recommends CO alarms on each level of the home, outside each sleeping area, plus a battery operated or battery backup alarm near sleeping areas during outages. For smoke, the American Red Cross gives the matching rule: install smoke alarms on every level of your home, including inside and outside bedrooms and sleeping areas. Put them on the ceiling or high on a wall, since smoke rises, follow the manufacturer's instructions, and keep alarms away from steamy bathrooms and cooking fumes that cause false alarms.
Alarms only work if they are maintained, and the routine is short. Test every alarm monthly by pressing its test button, and replace batteries at least once a year if your model requires it. Check the manufacture date: the Red Cross advises replacing smoke alarms that are 10 years or older, because sensors grow less reliable. Teach children what the alarm sounds like, and fold alarm checks into your fire escape practice, with two ways out of every room and a meeting spot outside.
Lesson 6
Indoor air can be worse than outdoor air, because homes hold the gases and particles their activities produce: cooking smoke, cleaning chemicals, moisture, dust, and fumes from fuel burning appliances. The EPA offers three basic strategies to improve indoor air quality, and their order matters. First, source control: identify and remove or reduce individual sources of pollution, which the EPA calls the most effective solution in most cases. Second, improve ventilation by increasing the amount of outdoor air coming indoors. Third, use air cleaners and filtration to supplement the first two, not replace them.
Ventilation is mostly fans used faithfully. Run the bathroom exhaust fan or open a window when showering, and use exhaust fans or open windows whenever cooking, running the dishwasher, or washing dishes, as the EPA's moisture guidance advises. Over a gas stove, the EPA recommends an exhaust fan vented to outdoors, because a hood that only recirculates sends cooking smoke and combustion gases back into the room. Vent dryers, stoves, and other moisture producing appliances outside where possible, and open doors and windows when weather allows, so fresh air can dilute what your home produces.
Filtration handles what is left in the air. A well fitted, higher efficiency filter in your heating and cooling system, changed on the maker's schedule, catches dust and particles as air circulates, and a portable air cleaner can help in a single room, following the EPA's guide to air cleaners in the home. Pair filtration with source habits: vacuum and dust with damp methods so particles are captured rather than scattered, keep smoking outside, and store strong chemicals closed and ventilated, a topic Lesson 8 takes up in full. Clean air at home is not a product. It is three habits stacked: fewer sources, more fresh air, and steady filtration.
Lesson 7
Roaches, mice, ants, and pantry moths are looking for three things: food, water, and shelter. HUD's pest free principle starts by taking those away. Seal cracks and openings throughout the home, store food in pest resistant containers, fix the leaks from Lesson 2 so there is no standing water, and keep kitchens and floors clean enough that a dropped crumb is an event, not a buffet. A home that offers pests nothing is a home most pests leave, and none of that requires a spray can.
When pests do appear, the EPA's integrated pest management approach, called IPM, gives a calm order of operations. Set an action threshold first, because seeing a single pest does not always mean control is needed. Monitor and identify the pest accurately, so you do not treat the wrong creature or use a pesticide that is not needed. Use prevention as the first line of control. Only then move to control methods, choosing effective, less risky options first, such as trapping, and using targeted pesticides only when monitoring shows the gentler methods are not working. Broadcast spraying of non specific pesticides is the last resort, not the first.
Practical tools follow that order. Use sticky traps to find where pests travel, baits in closed containers where children and pets cannot reach them, door sweeps and sealed gaps to close the roads in, and a vacuum for webs, egg cases, and droppings, emptied outside. HUD's guidance names the same least toxic approach: sticky traps and baits in closed containers, along with least toxic options such as boric acid powder used carefully in cracks and voids, away from children and food. If an infestation is large, in the walls, or involves stinging insects near an allergic family member, call a licensed pest professional and ask them to work the IPM way, in writing.
Lesson 8
The cabinet under a sink often holds the most dangerous objects in the home, at exactly child height. HUD's safe principle gives the core rule in one sentence: store poisons out of the reach of children, and properly label them. That means cleaners, laundry pods, medicines, pesticides, fuels, and solvents move up high, into a locked cabinet, or out to a locked storage area, and they stay in their original, labeled containers. A chemical poured into a drink bottle has lost its warning label and gained a terrible disguise, so decanting into food or drink containers is a habit to end today.
Organization does quiet safety work. Keep chemicals away from food storage, so a leaking bottle cannot drip onto anything eaten. Group products by job, return each one to its place after use, and read the label before the first use, not during an emergency: labels carry the ventilation, glove, and first aid instructions for that exact product. When cleaning mold, the EPA's guidance adds the working details: wear gloves suited to the cleaner you are using, protect your eyes with goggles without ventilation holes, and ventilate the room while you work.
Disposal finishes the job. Do not pour leftover pesticides, solvents, or strong chemicals into household trash or drains as a default; most communities run household hazardous waste collection days or sites for exactly these items, and your city or county page will list them. Take stock twice a year: consolidate half empty duplicates, retire products you no longer use through that collection route, and check that every remaining container still has a readable label and a working cap. Safe storage is not a locked fortress. It is height, labels, original containers, and a regular clear out.
Lesson 9
Healthy homes run on repairs, and the route to a repair differs if you rent or own. Renters start with speed and paper. The EPA's mold guidance tells renters to report all plumbing leaks and moisture problems immediately to the building owner, manager, or superintendent. Put the report in writing, keep a copy with the date, take photos of leaks, stains, peeling paint, or pests, and note any health symptoms and when they started. A polite, dated paper trail is what turns a hallway conversation into a repair that actually happens.
If a written request is ignored, you have more steps. The same EPA guidance says that where persistent water problems are not addressed, renters may contact local, state, or federal health or housing authorities, and your state health department is a listed contact. Many cities run housing inspection or code enforcement offices that can order repairs, and local legal aid and tenant organizations can explain the remedies your state and city allow, which vary widely, so get local advice before withholding rent or breaking a lease. For lead, know that your landlord must follow the EPA RRP rule when work disturbs paint in a pre-1978 rental, using lead safe certified firms.
Owners hold the schedule themselves, so the skill is prioritization. HUD's maintained principle says to inspect, clean, and repair routinely, taking care of minor problems before they become large ones. Work the order this course has taught: active water first; alarms next, because they guard sleep; then lead safe and radon work, using certified professionals where required; then ventilation, pests, and storage. Keep a simple repair log with dates, photos, contractor names, and test results. Whether you rent or own, documentation makes the next conversation easier.
Lesson 10
Finish the course in your own hallway, notebook in hand. Walk slowly, room by room, grading your home against the seven principles: dry, clean, safe, pest free, contaminant free, ventilated, and maintained. Start at the front door and look for peeling paint, especially if your home was built before 1978, door sweeps that let pests and weather in, and whether a smoke alarm covers this level. In the kitchen, check under the sink for leaks and drips, confirm cleaners are stored up high or locked and in their original containers, and test that the stove exhaust actually vents outside.
In bathrooms and the basement, hunt water. Look for mold on grout, ceilings, and around pipes, and use the 10 square foot rule: a small patch is a cleaning job after you fix its moisture source; anything bigger goes on the professional list. Check that bathroom fans run and vent out, and look for foundation cracks where radon and water enter. Press the test button on every smoke and carbon monoxide alarm, check their dates, and replace any unit 10 years or older. If your home has never been tested for radon, put a test kit at the top of the shopping list: fix at 4 pCi/L, consider fixing between 2 and 4.
End the walk by sorting the list, not by doing it all. Make three columns: do it this week for free, such as wet cleaning, sealing a gap, moving chemicals up high, and reporting a leak in writing; schedule it, such as a radon test, filter changes, and gutter cleaning; and hire it, for lead work in pre-1978 paint, asbestos concerns, large mold, radon mitigation, and furnace inspection. That sorted list is your healthy home plan, tied to the seven principles and the EPA numbers from this course. Repeat the walk every season, and your home will keep the grade you just gave it, or better.
Sources
This course is built from the free healthy housing guidance of the U.S. Environmental Protection Agency and the U.S. Department of Housing and Urban Development. Every cleanup size, radon level, and alarm rule in the lessons traces to one of these official sources.
Graduation
You learned the seven principles of a healthy home, how to fix moisture before cleaning mold, where lead hides and why its removal belongs to certified professionals, and how to test for radon and act at the right level. You placed and maintain carbon monoxide and smoke alarms, improved your indoor air in the EPA order of source control, ventilation, and filtration, handled pests without reaching for poisons first, stored chemicals safely, and learned how renters and owners each get repairs made. Your walk through checklist turns all of it into a plan for your own front door.
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This course is part of Starvard University, striving for greatness.
A note on accuracy: Much of what you read at Starvard was created with help from AI agents, working alongside people. We check what we can, but we cannot guarantee that everything here is true, current, or complete. If something really matters, your health, your money, a grade, a job, please verify it with a trusted source before you rely on it.