Environmental Health: The Complete Guide

How the air you breathe, the water you drink and the home you live in affect your health, and practical steps to cut exposure to lead, radon, mold, carbon monoxide, air pollution, chemicals, noise and UV. Written for US households, especially families with young children, pregnant people and anyone with heart or lung conditions.

Key numbers at a glance

Why your environment matters for your health

Environmental health is about the things around you that you take in without thinking: the air indoors and out, the water from your tap, dust and soil, the products under your sink, the noise you hear and the sunlight on your skin. Most of these exposures are low and harmless. A few, though, can quietly build up over months or years, and some, such as carbon monoxide, can be deadly within minutes. Because many hazards cannot be seen, smelled or tasted, the only way to know about them is to test or to follow simple routines.

What makes environmental health different from much of medicine is that the most effective steps happen at home rather than in a doctor's office. Testing a basement for radon, fitting a carbon monoxide alarm, checking a daily air quality forecast or wet-mopping dust in an older home are low-cost actions that prevent illness before it starts. A doctor is still important for blood tests, for managing conditions such as asthma that the environment can worsen, and for recognizing symptoms that may have an environmental cause.

This guide works through the hazards US agencies most often highlight for households, explains why each one matters and who is most at risk, and sets out what to do about it. You do not need to tackle everything at once. A one-time round of testing and a few habits cover most of the ground, and the plan at the end of the guide shows how to fit them into a year.

Who is most vulnerable

The same exposure does not affect everyone equally. Young children are especially vulnerable: they breathe more air, drink more water and eat more food for their body weight than adults, they crawl on floors and put hands and objects in their mouths, and their brains and lungs are still developing. Pregnant people matter because some exposures, such as lead, can pass to the developing baby. Older adults and people with heart disease, asthma, COPD or weakened immune systems are more sensitive to air pollution, mold and heat. Outdoor workers and people in older or poorly maintained housing often face higher exposures to begin with.

Lead in homes, soil and water

Lead is a metal that was widely used in paint, gasoline and plumbing before its health effects were understood. It harms the developing brain and nervous system, and no safe blood lead level has been identified in children. Even low levels are linked to effects on learning, attention and behavior that cannot be fully reversed. Children with lead in their blood often look and act healthy, which is why testing matters. In adults, lead is linked to high blood pressure and kidney problems, and in pregnancy it can affect the developing baby.

The most common source for US children is old lead-based paint and the dust it creates. Homes built before 1978 are the most likely to contain lead paint. When that paint chips, peels or is disturbed during renovation, it forms fine dust that settles on floors and windowsills and ends up on hands and toys. Soil near older homes and busy roads can also hold lead, and some imported spices, cosmetics, folk remedies, toys and ceramic dishes have been found to contain it. Adults who work with lead in construction, battery recycling or at firing ranges can carry dust home on clothes and shoes.

The CDC uses a blood lead reference value of 3.5 mcg/dL to identify children with higher levels than most children their age, so that families can find and remove the source. Ask your child's doctor about a blood lead test, especially around ages 1 and 2, if you live in an older home, or if anyone in the household works with lead. Many state Medicaid programs require testing of young children, and the test is usually a simple finger-prick or blood draw.

• Wet-mop floors and wet-wipe windowsills regularly, and wash children's hands and toys often
• Never dry sand, dry scrape or use an open flame on old paint
• Hire a lead-safe certified contractor for renovation, repair or painting in homes built before 1978
• Leave shoes at the door, and wash work clothes from lead-related jobs separately
• Avoid imported spices, cosmetics, folk remedies or ceramic dishes that may contain lead

Lead in drinking water

Lead rarely comes from the water source itself. It usually enters water from lead service lines, older solder or brass fixtures as water sits in the pipes. The EPA's health goal for lead in drinking water is zero. Ask your water utility whether your home has a lead service line. If water has been sitting for several hours, run the cold tap until it feels noticeably colder before drinking it. Use only cold tap water for drinking, cooking and mixing baby formula, because hot water draws more lead from pipes, and boiling does not remove lead. If you use a filter, choose one certified to NSF/ANSI Standard 53 for lead reduction.

Radon: the hidden gas in many homes

Radon is a radioactive gas that forms naturally as uranium in soil and rock breaks down. It seeps into buildings through cracks in foundations, gaps around pipes and sump pits, and it can build up indoors. You cannot see, smell or taste it. According to the EPA, radon is the second leading cause of lung cancer in the US and the leading cause among people who have never smoked, and it is linked to about 21,000 lung cancer deaths a year. About 1 in 15 US homes is estimated to have an elevated level.

Radon levels vary a great deal from house to house, even on the same street, so a neighbor's result does not predict yours. New homes, homes without basements and homes in areas considered low-risk can all have high levels. The only way to know is to test. Short-term test kits are inexpensive and are placed in the lowest lived-in level of the home for a few days, then mailed to a lab. Keep windows and outside doors closed as much as possible during the test and avoid testing during strong storms, which can skew results. Many state radon programs offer free or low-cost kits.

The EPA recommends fixing a home if the radon level is 4 pCi/L or higher, confirmed with a follow-up test, and considering a fix for levels between 2 and 4 pCi/L. The most common fix is a vent pipe and fan system that draws radon from beneath the foundation and releases it above the roof. A qualified radon mitigation contractor can install one, usually in a day. Retest after mitigation, every 2 years afterward, and after major renovations. Smoking greatly multiplies the lung cancer risk from radon, so if you smoke, quitting is the single biggest step you can take; free help is available at 1-800-QUIT-NOW.

Drinking water: public systems and private wells

Most Americans get their water from public water systems, which must meet EPA standards for dozens of contaminants and treat and test their water regularly. Each year, your utility must give you a Consumer Confidence Report, also called an annual water quality report, that lists what was found in your water and whether any standards were exceeded. Reading it takes a few minutes and tells you far more than the taste or look of the water. If you rent, your landlord or utility can provide it.

Tens of millions of people in the US, however, rely on a private well, and EPA drinking water rules do not apply to private wells. Testing and maintenance are the owner's responsibility. Wells can be contaminated by bacteria from septic systems or animal waste, by nitrate from fertilizer, and by naturally occurring substances such as arsenic or uranium, depending on local geology. Clear, good-tasting water can still be unsafe.

Test a private well at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH, and use a state-certified laboratory. Ask your local health department which other contaminants are common in your area. Retest after flooding, repairs to the well, or any change in taste, smell or color. Keep the wellhead capped, keep pesticides, fuel and animal waste away from it, and have your septic system inspected regularly. After a flood, do not drink well water until it has been tested or disinfected.

Nitrate and babies

Nitrate in drinking water is a particular concern for babies. High levels can interfere with how the blood carries oxygen in infants, a condition sometimes called blue baby syndrome. The EPA standard for nitrate in public water is 10 mg/L, measured as nitrogen. If you use well water, do not use it to mix baby formula until nitrate levels have been checked, and do not boil water to reduce nitrate, because boiling concentrates it. If tests show a high level, use another safe water source for the baby and talk to your child's doctor.

Mold, dampness and indoor humidity

Mold is a type of fungus that grows on damp surfaces, often after leaks, flooding or long periods of high humidity. Its spores are everywhere, indoors and out, so the goal is not to eliminate them but to stop them from finding the moisture they need to grow. Damp and moldy homes are linked to stuffy nose, wheezing, coughing, eye irritation and worse asthma, and people with weakened immune systems or chronic lung disease can develop more serious infections.

Controlling moisture is the key to controlling mold. The EPA recommends keeping indoor humidity below 60%, ideally between 30% and 50%, which you can check with an inexpensive humidity meter. Fix leaks in roofs, pipes and windows as soon as possible, use exhaust fans in bathrooms and kitchens, and run a dehumidifier in damp basements. After a leak or spill, dry wet materials within 24 to 48 hours to prevent mold growth.

If you find mold, you can usually clean small areas, up to about 10 square feet, yourself. Scrub it off hard surfaces with detergent and water and dry them completely. Throw out porous materials such as carpet padding or ceiling tiles that stay moldy. Wear an N95 respirator, gloves and goggles while cleaning. Painting or caulking over mold does not solve the problem. For larger areas, flood damage, or if you have asthma or a weakened immune system, consider a professional. Testing to identify the type of mold is usually not needed, because you should remove it whatever the type.

• Never mix bleach with ammonia or other cleaners, which releases toxic gases
• Look for hidden moisture behind furniture, under sinks and around windows if you notice a musty smell
• Vent clothes dryers to the outside

Carbon monoxide and gas appliances

Carbon monoxide (CO) is a colorless, odorless gas produced whenever fuel is burned, by furnaces, water heaters, gas stoves, fireplaces, cars, generators, grills and camp stoves. When it builds up indoors, it displaces oxygen in the blood. Early symptoms such as headache, dizziness, weakness, nausea and confusion are easy to mistake for flu, and people who are asleep or drunk can die before they notice anything. Poisonings rise during winter and after storms, when people run generators or use fuel-burning devices indoors for heat.

A working CO alarm is the most important protection. Install them on every level of your home and outside sleeping areas, test them monthly, and replace batteries and the units themselves as the maker directs. Have gas furnaces, water heaters and chimneys inspected every year by a qualified technician. Never use a gas oven or stovetop to heat your home, and never run a generator, grill, camp stove or car in a garage, basement or other enclosed space, even with the door open. Portable generators belong outdoors only, at least 20 feet from windows, doors and vents.

If a CO alarm sounds, or anyone has symptoms that could be from CO, do not wait to see whether people feel worse. Get everyone, including pets, outside to fresh air right away and call 911 from outside. Do not go back in until emergency responders say it is safe. Tell the doctors if anyone is pregnant, since carbon monoxide can harm a developing baby even when the parent's symptoms are mild, and get the source checked and repaired before you use that appliance again.

Gas stoves and indoor air

Gas stoves also release nitrogen dioxide, small amounts of carbon monoxide and fine particles while they burn. These can irritate the airways and are linked to worse asthma symptoms, especially in children. Use a range hood that vents outdoors every time you cook, and cook on the back burners where the hood captures more fumes. If you do not have a vented hood, open a window or run an exhaust fan. These steps also help with smoke and particles from frying, toasting and other cooking on any type of stove.

Outdoor air, wildfire smoke and the AQI

Outdoor air pollution comes mainly from vehicles, power plants, industry and, increasingly, wildfires. The pollutants that matter most for health are ground-level ozone, which forms on hot, sunny days, and fine particles, which are small enough to travel deep into the lungs and into the bloodstream. Polluted air is linked to asthma attacks, worsening COPD, heart attacks and strokes, and smoke from distant wildfires can affect air quality hundreds of miles away.

The Air Quality Index (AQI) turns pollution levels into a simple color-coded scale from 0 to 500. Green (0 to 50) is good. Yellow (51 to 100) is moderate, and a small number of unusually sensitive people may be affected. Orange (101 to 150) is unhealthy for sensitive groups: people with heart or lung disease, children, older adults, pregnant people and outdoor workers. Red (151 to 200) is unhealthy for everyone, purple (201 to 300) is very unhealthy, and maroon (301 or higher) is hazardous. You can check the daily AQI and forecast on AirNow or in most weather apps.

On orange days or worse, people in sensitive groups should cut back on long or hard outdoor exercise, and everyone should do so on red days or worse. Ozone is often highest on summer afternoons, so moving a run to early morning can help. During wildfire smoke, keep windows and doors closed, run a portable HEPA air cleaner, and use the highest-efficiency filter your heating and cooling system can take. Avoid adding to indoor pollution by burning candles or wood or frying food. If you must be outdoors in heavy smoke, a well-fitting N95 respirator offers far more protection than a cloth or surgical mask.

• If you have asthma or COPD, keep rescue inhalers and other medicines on hand and follow your action plan
• Choose a clean-air room at home, ideally one with a portable air cleaner, for the worst smoke days
• Ask your doctor before smoke season whether your treatment plan needs adjusting

Household chemicals and pesticides

Household cleaning products are among the most common causes of poisoning in young children, and most poisonings happen at home when a product is being used or has just been left out. Single-load laundry packets are a particular risk because they look like candy and can burst in a child's mouth. Store cleaners, laundry products and drain openers in their original containers, up high and locked, and away from food. Close containers right after each use, even if you will use them again in a minute, and never pour chemicals into drink bottles or food containers.

Mixing products can release toxic gases. Never mix bleach with ammonia, vinegar or other acids, or rubbing alcohol, and do not use two products in a row on the same surface without rinsing. Use one product at a time, follow the label, and open windows or run a fan while you clean. More product does not mean more cleaning power, only more fumes.

Pesticides, including insect sprays, rodent baits and weed killers, are designed to harm living things. Their label is a legal document, and using a product other than as directed is unsafe and against the law. Look for an EPA registration number, which shows the product has been reviewed for its labeled use, and avoid illegal products such as unlabeled "Chinese chalk". Integrated pest management, which removes the food, water and shelter pests need by sealing cracks, fixing leaks and storing food in sealed containers, often reduces the need for chemicals. When you do use them, choose baits in child-resistant stations over sprays and foggers, keep children and pets away from treated areas for as long as the label says, and wash your hands afterward.

• Save Poison Control, 1-800-222-1222, in your phone and post it at home; it is free, confidential and open 24/7
• Call Poison Control right away for any swallowing, skin, eye or inhalation exposure, even if the person seems fine
• Have the product container with you when you call

Noise and your hearing

Noise-induced hearing loss is permanent but preventable. Loud sound damages the tiny hair cells in the inner ear that turn sound into signals for the brain, and once they are destroyed they do not grow back. Damage can come from a single very loud event, such as a gunshot or firework at close range, or build up slowly from repeated exposure to power tools, lawn equipment, concerts, sporting events and headphones turned up high. Ringing in the ears or muffled hearing after a noisy event is a warning sign that your ears were overloaded.

Sound is measured in decibels, written dBA when adjusted for how people hear. Sounds at or below 70 dBA are unlikely to damage hearing, even over long periods; normal conversation is about 60 dBA. Long or repeated exposure at 85 dBA and above can cause hearing loss, and lawn mowers, power tools and concerts can easily reach that. NIOSH recommends limiting exposure to 85 dBA averaged over 8 hours, and every 3 dBA increase halves the safe time: about 4 hours at 88 dBA and only about 15 minutes at 100 dBA.

Wear earplugs or earmuffs for mowing, power tools, shooting, concerts and other loud activities, and keep a pair in your car or bag. Cotton balls and tissue do not protect hearing. Turn down personal listening devices, and use noise-canceling headphones so you do not need to raise the volume over background noise. Move away from loudspeakers and take breaks in quieter areas. A free sound level meter app can give you a rough idea of how loud a place is. If you are often around loud noise, get your hearing tested.

Sun, UV and heat

Ultraviolet (UV) radiation from the sun is the main preventable cause of skin cancer, and it also causes sunburn, eye damage and premature skin aging. UV strength depends on the time of day, season, altitude and reflection from snow, sand and water, not on how warm it feels, so you can burn on a cool or cloudy day. The UV Index forecast, available from the EPA and in weather apps, rates the expected strength from low (0 to 2) through moderate (3 to 5), high (6 to 7) and very high (8 to 10) to extreme (11 or higher). From about 3 upward, sun protection is worth planning.

Seek shade, especially between 10 a.m. and 4 p.m., and wear a wide-brimmed hat, UV-blocking sunglasses and clothing that covers your arms and legs. The American Academy of Dermatology recommends a broad-spectrum, water-resistant sunscreen with SPF 30 or higher, reapplied every 2 hours and after swimming or sweating. Most people use too little: an adult needs about 1 ounce, roughly a shot glass, to cover exposed skin. Keep babies under 6 months out of direct sun and talk to your child's doctor about sunscreen for them. Avoid tanning beds and sunlamps, which also give off UV.

Extreme heat is a growing environmental health risk and one of the leading weather-related causes of death in the US. Older adults, babies and young children, outdoor workers, athletes, and people with heart disease, obesity or mental illness, or who take certain medicines, are most at risk. Drink water regularly, spend the hottest hours in air conditioning if you can, including a public cooling center, and check on neighbors and relatives who live alone. Never leave a child or pet in a parked car, even briefly. Heat stroke, with confusion, fainting or hot skin, is an emergency.

Testing, costs and help in the US

Many environmental checks are cheap or free. State radon programs often offer free or discounted test kits. Blood lead testing for children is usually covered by health insurance and Medicaid. Many local and state health departments help private well owners find certified labs, and some offer reduced-cost testing. Your water utility's annual report is free. Poison Control is free and confidential. CO alarms, humidity meters and food and appliance thermometers cost little compared with the problems they prevent.

Larger fixes, such as lead paint removal, radon mitigation or replacing a lead service line, cost more, but help is often available. Some cities and states run lead hazard control and lead service line replacement programs, especially for families with young children or lower incomes. If you rent a home built before 1978, federal rules require landlords to disclose known lead-based paint hazards, and your local health or housing department can advise if you have concerns about lead, mold or broken heating. When you hire someone, check that they are certified for the job, such as a lead-safe certified renovator or a qualified radon mitigation contractor.

Your doctor is part of the picture too. Tell them about your home and work environment, especially if symptoms improve when you are away from home, if you live in an older house, if you have a private well, or if you work with chemicals, lead, dust or loud noise. That context can change which tests they order and how they treat conditions such as asthma, headaches or hearing loss.

Myths and a year-round plan

A few common beliefs leave people exposed. Clear, good-tasting water is not necessarily safe, and boiling water removes germs but not lead or nitrate. New homes and homes without basements can still have high radon. Opening a garage door does not make it safe to run a car or generator inside. Cloth and surgical masks do little against wildfire smoke. Bleach does not make mold safe to leave in place. And a cloudy or cool day does not mean UV is low. The common thread is that you cannot rely on your senses for most environmental hazards; you need to test, check a forecast or follow a routine.

Spreading the work through the year makes it manageable. Many of these tasks take minutes and only need doing once, or once a season. Start with the ones that protect against the fastest-acting dangers, carbon monoxide and poisoning, then work through testing. Revisit the list whenever you move, renovate, have a baby or someone at home develops asthma, since each of those changes which hazards matter most.

• Now: fit and test CO alarms on every level, save Poison Control in your phone, and lock up chemicals and medicines
• Fall: have the furnace, water heater and chimney inspected, and test your home for radon as windows close for winter
• Winter: check indoor humidity, keep generators outdoors at least 20 feet from the house, and test CO alarms monthly
• Spring: test a private well, read your utility's water quality report, and check for leaks and damp after winter
• Summer: check the AQI and UV Index daily, plan for heat and wildfire smoke, and pack hearing protection for loud events
• Every year: ask your child's doctor whether a blood lead test is due, and review your plan if you move or renovate

Every guide in this topic

• Lead in Homes and Water: Sorting the Evidence From the Noise
• Radon Testing: What Published Guidance Supports
• What the Guidance Really Says About Mold at Home
• What the Guidance Really Says About Drinking Water and Private Wells
• What the Guidance Really Says About Air Pollution and the AQI
• What the Guidance Really Says About Indoor Air and Gas Stoves
• The Evidence on Pesticides at Home, Without the Hype
• What the Guidance Really Says About Everyday Noise Exposure
• The Evidence on Sun and the UV Index, Without the Hype
• Household Chemicals: What the Evidence Actually Says

Frequently asked questions

Should my child be tested for lead?

Ask your child's doctor, especially around ages 1 and 2, if you live in a home built before 1978, if anyone at home works with lead, or if your child has eaten paint chips or uses imported products that may contain lead. Many Medicaid programs require testing of young children. No safe blood lead level has been identified, so finding and removing sources matters.

Is my tap water safe to drink?

If you are on public water, read your utility's annual Consumer Confidence Report, which shows what was found and whether standards were met, and ask whether you have a lead service line. Private wells are not covered by EPA rules, so test yours at least yearly for coliform bacteria, nitrates, total dissolved solids and pH, using a state-certified lab.

Does boiling water remove lead?

No. Boiling kills germs but does not remove lead, and it can concentrate nitrate. To lower lead exposure, use only cold tap water for drinking, cooking and baby formula, run the tap after water has sat for hours, and consider a filter certified to NSF/ANSI Standard 53 for lead reduction. Ask your utility about your service line.

How do I test my home for radon?

Buy a short-term test kit, often free or low-cost through your state radon program, and place it in the lowest lived-in level of your home with windows closed for the time stated. If the result is 4 pCi/L or higher, do a follow-up test and, if confirmed, hire a qualified mitigation contractor. Retest every 2 years.

Is black mold more dangerous than other mold?

Any mold growing indoors can cause symptoms such as stuffy nose, coughing, wheezing and worse asthma, so the advice is the same whatever the color or type: remove it and fix the moisture problem. Testing to identify the species is usually not needed. Clean small areas yourself with detergent and water, and get professional help for large areas or flood damage.

What are the signs of carbon monoxide poisoning?

Headache, dizziness, weakness, nausea, vomiting, chest pain and confusion, often in several people or pets at once, and often better when you leave the house. People who are asleep may have no warning. If you suspect CO or an alarm sounds, get everyone outside to fresh air right away and call 911 from outside.

When should I stay indoors because of air pollution?

Check the AQI on AirNow or a weather app. At orange (101 to 150), people with heart or lung disease, children, older adults, pregnant people and outdoor workers should cut back on long or hard outdoor activity. At red (151 or higher), everyone should. During wildfire smoke, keep windows closed and run a HEPA air cleaner.

Are gas stoves bad for my health?

Gas stoves release nitrogen dioxide, carbon monoxide and fine particles, which can irritate airways and are linked to worse asthma, especially in children. You can cut exposure by using a range hood that vents outdoors every time you cook, cooking on back burners, and opening a window if you lack a vented hood. Never use a gas stove to heat your home.

How loud is too loud?

Long or repeated exposure to sound at 85 dBA or above can damage hearing. NIOSH recommends limiting exposure to 85 dBA over 8 hours, and every 3 dBA increase halves the safe time. If you have to raise your voice to be heard at arm's length, wear hearing protection or move away.

Do I need sunscreen on a cloudy day?

Yes. UV passes through clouds and reflects off snow, sand and water, and it does not depend on temperature. Check the UV Index; at 3 or higher, use broad-spectrum, water-resistant sunscreen with SPF 30 or higher, reapplied every 2 hours and after swimming or sweating, along with shade, a hat and sunglasses. Keep babies under 6 months out of direct sun.

When to speak to a doctor

See your doctor about blood lead testing if a child may have been exposed to lead or anyone at home works with it; if asthma, COPD, a lasting cough or nasal symptoms worsen at home, on poor air days or improve when you are away; if you have lived with high radon and smoke or used to, or have a cough that will not go away, are coughing up blood or losing weight without trying; if you have ringing in the ears lasting more than a day or muffled hearing; or for a new or changing mole. See a doctor right away for sudden hearing loss. Call Poison Control at 1-800-222-1222 right away for any swallowing, skin, eye or breathing exposure to a household chemical or pesticide, or if a child swallows paint chips. If a carbon monoxide alarm sounds or anyone may have CO poisoning, get everyone outside and call 911. Also call 911 for severe trouble breathing, an asthma attack not relieved by a rescue inhaler, chest pain, a seizure, a person who is unconscious or hard to wake, a baby with bluish skin around the lips, or signs of heat stroke such as confusion or fainting.

Where this comes from

• CDC — Childhood Lead Poisoning Prevention
• EPA — Basic Information about Lead in Drinking Water
• EPA — A Citizen's Guide to Radon
• EPA — A Brief Guide to Mold, Moisture, and Your Home
• EPA — Private Drinking Water Wells
• AirNow — Air Quality Index (AQI) Basics
• CDC — Carbon Monoxide Poisoning Basics
• NIOSH — Noise and Hearing Loss
• EPA — UV Index Scale
• American Academy of Dermatology — How to Prevent Skin Cancer

How this page was put together

Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.

Medical disclaimer

This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.