Avoiding harm

The biggest preventable risks#

Heart disease, cancer, and unintentional injuries were again the leading US causes of death in 2024, and much of each traces to a short list of exposures. The categories below overlap (alcohol contributes to crashes and drownings), so they do not add up.

Air pollution is harder to count at the national level but is a leading risk worldwide: it accounted for 8.1 million deaths in 2021, making it the second leading risk factor for death. Falls are the leading cause of injury for adults 65 and older, with a death rate of 69.9 per 100,000 in 2023 and rising; see muscle, bone, and mobility for prevention.

Tobacco and nicotine#

Smoking#

Smoking kills more than 480,000 Americans a year, including through secondhand smoke. In a study of more than 200,000 US adults, current smokers had about three times the death rate of never smokers and lost more than 10 years of life expectancy.

Quitting helps at every age Strong, and earlier is better. People who quit at 25 to 34, 35 to 44, and 45 to 54 gained about 10, 9, and 6 years of life compared with those who kept smoking, and quitting before 40 reduced the excess risk of death from continued smoking by about 90%.

If you have a significant smoking history, ask about lung cancer screening; see cancer.

Vaping#

The CDC's position is that no tobacco product is safe, including e-cigarettes, whose aerosol can contain heavy metals, fine particles, and carcinogens. Nicotine harms the developing brain until about age 25.

For adults who smoke, e-cigarettes may help if they completely replace cigarettes; using both is not a safe middle ground. The August 2026 Cochrane review found high-certainty evidence that nicotine e-cigarettes help more people quit smoking than nicotine patches or gum, about four more quitters per 100 Strong. Long-term safety is unknown, so aim to quit nicotine eventually.

Nicotine pouches#

Nicotine pouches (such as Zyn and Velo) sit between lip and gum. In January 2025 the FDA authorized marketing of 20 Zyn products, the first pouches it has authorized, because they contain far fewer harmful chemicals than cigarettes or snuff. Authorization is not approval or a finding of safety. Pouches deliver a highly addictive drug and make sense only as a complete substitute for smoking or chewing tobacco.

The optimal amount of nicotine is none. Nicotine without smoke is far less harmful than cigarettes, but it has effects that could contribute to heart events, especially in people with heart disease. Do not start pouches or gum for focus or weight control.

Quitting#

Medication roughly doubles to triples the odds of quitting compared with placebo (EAGLES 2016), and counseling adds more. The US Preventive Services Task Force gives an A grade to offering adults both behavioral support and FDA-approved medication.

Alcohol#

Optimal: none. For most outcomes the lowest risk is at zero. Cancer risk rises from the first drink (below), blood pressure rises in a straight line with no safe threshold (about 1.3 mm Hg higher systolic at one drink a day in a 2023 pooled analysis), and in 107,845 Europeans one drink a day was linked to a 16% higher risk of atrial fibrillation. The live debate is whether light drinking has any offsetting heart benefit, and even its defenders do not claim one for cancer Moderate. If you choose to drink, Canada's low-risk range is 2 or fewer drinks a week, never more than 2 in a day. Guideline minimum: the US Dietary Guidelines say only to drink less (below).

The evidence in brief:

• Cancer. The World Health Organization's position is that no level of drinking is safe for health. The US Surgeon General's January 2025 advisory highlighted alcohol as a cause of at least seven cancers, with risk rising even at low intake. Alcohol caused about 5% of US cancer cases in 2019, nearly 100,000 cases and 25,000 deaths.
• Mortality. The famous "J-curve," in which moderate drinkers outlive abstainers, comes largely from counting sick former drinkers as abstainers. A 2023 meta-analysis of 107 studies with 4.8 million people that corrected for this found no survival benefit for low-volume drinkers compared with lifetime nondrinkers, and higher mortality from about three drinks a day (45 g of alcohol), with women at higher risk at lower intakes.
• A dissenting review. A 2024 National Academies review found 16% lower all-cause mortality in moderate drinkers than never drinkers, from eight studies with risk-of-bias concerns, and in the same report a 10% higher risk of breast cancer.
• Guidelines. The 2025–2030 Dietary Guidelines for Americans dropped numeric limits and say only to "consume less alcohol for better overall health". Canada's 2023 guidance is more specific (below).

Alcohol also fragments sleep (see sleep) and triggers atrial fibrillation. In a 2020 trial of 140 regular drinkers with atrial fibrillation, those assigned to abstain had recurrences in 53% versus 73% of those who kept drinking Moderate. See heart.

In absolute terms, the Surgeon General's advisory estimated that of 100 women who have less than one drink a week, about 17 will develop an alcohol-related cancer, compared with 19 of those who have one drink a day and about 22 who have two. For men, the numbers are 10, 11, and 13.

A US standard drink is 14 grams of alcohol: 12 ounces of 5% beer, 5 ounces of 12% wine, or 1.5 ounces of 40% spirits. Binge drinking, which drives most injuries, means five or more drinks for men or four or more for women in about two hours.

If you drink, keep it to 2 or fewer drinks a week, avoid binges, and try alcohol-free months to see how you feel. Once a year, answer the three AUDIT-C questions, a validated check for risky drinking, at your checkup or on your own. Guideline minimum: the USPSTF recommends that primary care clinicians screen all adults for unhealthy alcohol use, with no set interval. If cutting back is hard, ask your doctor about counseling and medication, or call the SAMHSA helpline.

Cannabis and other drugs#

Cannabis#

• Heart and stroke. In a 2024 study of 434,104 US adults, daily cannabis use was associated with 25% higher odds of heart attack and 42% higher odds of stroke, even among people who had never smoked tobacco. The data were self-reported and cross-sectional.
• Addiction. About 3 in 10 people who use cannabis have cannabis use disorder, and the risk is higher with frequent use, early starts, and concentrated THC products.
• Vomiting syndrome. Heavy, long-term use can cause cannabinoid hyperemesis syndrome, cycles of severe vomiting. In Ontario, emergency visits for it rose 13-fold between 2014 and 2021.
• Psychosis. In a European study, daily use was linked to about 3 times the odds of a first psychotic episode, and daily use of high-potency cannabis (10% THC or more) to nearly 5 times.
• Driving. Cannabis impairs driving skills; 25% of seriously injured drivers at seven trauma centers tested positive, though a positive test does not prove impairment.

The optimal amount is none. If you use cannabis, use it occasionally rather than daily, avoid concentrates and high-THC products, go slowly with edibles, and do not drive high.

Other drugs and fentanyl#

Overdose deaths fell sharply in 2024, to 79,384, with the rate involving synthetic opioids such as fentanyl down 35.6% from 2023.

Illegally made fentanyl is up to 50 times stronger than heroin and is mixed into heroin, cocaine, and methamphetamine and pressed into counterfeit pills made to look like oxycodone or Xanax. Any pill not from a pharmacy should be assumed to be counterfeit. The animal sedative xylazine is increasingly mixed in as well; it causes severe wounds and is not reversed by naloxone, though naloxone should still be given because opioids are usually present too.

Fentanyl test strips are inexpensive and give results in about 5 minutes, but a negative test does not guarantee safety, because strips may miss more potent fentanyl-like drugs such as carfentanil. Never use alone. For treatment of any substance use disorder, including medications for opioid use disorder such as buprenorphine and methadone, see FindTreatment.gov.

Injuries#

Driving and road safety#

In 2024, 39,254 people died in US crashes. Speeding was a factor in 29% of those deaths, and only 46% of drivers killed were known to be belted.

• Buckle up, every seat, every trip. Seat belts reduce serious crash injuries and deaths by about half Strong.
• Choose a safe car. The Insurance Institute for Highway Safety rates crash protection and crash avoidance; its Top Safety Pick lists are a good shortlist. Automatic emergency braking with forward collision warning cut rear-end crashes in half in IIHS studies.
• Drive with zero alcohol. The legal limit is not a safe level: crash risk rises steadily with any alcohol and sharply above 0.05%, and after Utah lowered its limit to 0.05% in 2018, its fatal crash rate fell 20%, against 6% elsewhere. In 2022, 13,524 people died in crashes involving an alcohol-impaired driver, 32% of all traffic deaths. The same rule applies to cannabis and sedating medicines.
• Drive at or below the limit. Raising impact speed from 40 to 60 mph increases the crash energy the car must absorb by 125%.
• Put the phone away. Nine people a day die in US crashes reported to involve a distracted driver. Use do-not-disturb mode while driving.
• Don't drive drowsy. Drivers who slept less than four hours in the past day had 11.5 times the crash rate of well-rested drivers, comparable to driving well over the legal alcohol limit. Untreated sleep apnea is a common cause; see sleep.
• Plan for aging. Drivers 70 and older have higher fatal crash rates per mile than middle-aged drivers; vision checks and medication reviews help. See Aging well after 65 for warning signs and how to decide when to stop.

Bicycles and helmets#

In 2024, 1,075 cyclists were killed in crashes with motor vehicles in the US, the third-highest number on record. In a meta-analysis of 40 studies with more than 64,000 injured cyclists, helmets cut the odds of head injury by about half and of serious head injury by about 70%, and fatal head injury by about 65% Strong. Wear one on bikes, e-bikes, scooters, motorcycles, and ski slopes, and use lights day and night. Motorcycles are the riskiest common way to travel: per mile, deaths in 2024 were almost 27 times those in cars. The optimal choice is not to ride; if you do, train, wear a helmet and protective gear, and never ride after drinking.

Firearms#

More than 48,000 people died from firearm injuries in the US in 2022, and more than half of those deaths were suicides. Most people who use a firearm in a suicide attempt die from the injury, which is why access matters. A 2014 meta-analysis found that access to a firearm at home was associated with about 3 times the odds of suicide and 2 times the odds of homicide victimization for household members.

If you own firearms, storage is the key variable. In a study of youth suicides and unintentional shootings, guns stored locked, unloaded, and separate from locked ammunition were much less likely to be involved Moderate. Practical steps:

• Store firearms unloaded in a locked safe or lockbox, or with a cable or trigger lock.
• Lock ammunition separately.
• During a household mental health crisis, consider temporary storage outside the home, and call or text 988.

Drowning#

About 4,000 people drown in the US each year, and drowning is the leading cause of death for children ages 1 to 4. Prevention is simple: swim lessons, life jackets on boats, close supervision of children without phones or alcohol, fenced pools, and no alcohol when swimming or boating.

Fire and carbon monoxide#

Home fires killed 2,890 people in 2023. The US Fire Administration recommends smoke alarms in every bedroom, outside each sleeping area, and on every level, ideally interconnected so they all sound together. Test them monthly, replace 9-volt batteries yearly, and replace each alarm 10 years from its manufacture date.

Carbon monoxide, an odorless gas from furnaces, generators, grills, and cars, kills more than 400 Americans a year outside of fires and sends more than 100,000 to emergency departments. Install battery-powered or battery-backup CO alarms near every sleeping area, check them when you change the clocks, and replace them on the manufacturer's schedule. Never run a generator, grill, or camp stove indoors or in a garage. Flu-like symptoms in several people at once suggest CO; get out and call 911.

Air quality#

Outdoor air and wildfire smoke#

Fine particles (PM2.5, particles small enough to reach deep into the lungs and bloodstream) cause heart disease, stroke, lung disease, and lung cancer. In February 2024 the EPA tightened the annual PM2.5 standard to 9.0 micrograms per cubic meter; in March 2025 it announced it would reconsider that standard, and the outcome is pending as of October 2026.

You can control your exposure on bad days. Check the Air Quality Index (AQI) at AirNow or a weather app.

A reasonable rule: at orange, sensitive groups shorten hard outdoor exercise; at red or worse, everyone moves it indoors. During wildfire smoke, keep windows closed, run a HEPA purifier or a central system with a high-efficiency filter, and if you must be outside, wear a NIOSH-approved respirator such as an N95.

Indoor air and gas stoves#

Cooking is often the biggest source of indoor pollution. In a study of 87 homes, gas and propane burners emitted 10 to 25 times more benzene, a carcinogen, than electric burners, sometimes raising bedroom levels above health benchmarks for hours. Induction stoves emitted none Moderate. A 2024 modeling study estimated that gas stoves raise long-term nitrogen dioxide exposure by an amount equal to 75% of the WHO guideline on average and may account for about 50,000 current cases of childhood asthma in the US.

If you cook with gas, run a range hood that vents outdoors every time, use the back burners, and open a window. When the stove needs replacing, induction is the clean option.

Purifiers and ventilation#

Optimal: run a HEPA purifier in your bedroom every night, not only on smoke days, especially if you live near busy roads or in a polluted city. In 10 trials with 604 people, home air filtration lowered systolic blood pressure by about 4 mm Hg over about two weeks Moderate, a surrogate outcome but a cheap, low-risk one. Guideline minimum: the EPA treats air cleaners as a supplement to removing pollution sources and ventilating.

A portable air cleaner with a HEPA filter removes particles. Size it by its clean air delivery rate (CADR): the industry's two-thirds rule says the smoke CADR should be at least two-thirds of the room's floor area in square feet, so a 10-by-12-foot room (120 square feet) needs at least 80. For gases and odors, you need a substantial activated carbon filter; there is no standard rating for gas removal. Coway, Blueair, and Levoit are widely sold examples; trust an AHAM Verifide CADR over marketing. Avoid ozone generators.

A carbon dioxide monitor (Aranet4 and Awair are common examples) is a simple way to check ventilation: if CO2 keeps climbing in a closed bedroom or office, open a window or run ventilation.

Radon#

Radon is an odorless radioactive gas that seeps from soil into homes. It is the second leading cause of lung cancer Strong in the US after smoking and the leading cause in people who have never smoked, responsible for an estimated 21,000 deaths a year, about 2,900 of them in never smokers. The risk is much higher for smokers.

Testing is the only way to know your level. Optimal: test every home, and fix it at 2.7 pCi/L (100 Bq/m³) or higher, the World Health Organization's reference level. WHO estimates that lung cancer risk rises about 16% for every 100 Bq/m³ of long-term exposure and treats the relationship as linear, with no threshold, so lower is better even below the EPA's action level Strong. Guideline minimum: the EPA recommends that all homes be tested and fixed at 4 pCi/L or higher.

Short-term test kits are cheap at hardware stores, and some state programs give them away free. Test the lowest level you regularly use. Retest every two years (the EPA treats a test older than two years as no longer recent when a home is sold), after renovations, if you start using a lower floor, and after any mitigation. Mitigation, usually a fan and pipe that vent soil gas above the roof, can cut levels by up to 99% and costs about the same as other common home repairs.

Drinking water#

Optimal: read your utility's annual report, test your own tap once for lead, and filter the water you drink and cook with through a filter certified for lead and PFAS (below). USGS sampling found at least one PFAS chemical in about 45% of US tap water, and a utility's report cannot show lead that comes from your own pipes. Retest after plumbing work or if your utility reports a lead problem Moderate. Guideline minimum: utilities test and publish an annual Consumer Confidence Report; the EPA says home testing is the only sure way to know about lead from household plumbing but sets no schedule.

Lead. There is no safe level of lead, and the main source in drinking water is lead pipes. EPA's 2024 Lead and Copper Rule Improvements require water systems to identify and replace lead service lines within 10 years. Ask your utility whether your line is lead, especially in a home built before 1986. Until it is replaced, use cold water for drinking and cooking and a certified filter.

PFAS. These "forever chemicals" from nonstick, stain-resistant, and waterproof products and firefighting foam persist in the body. In April 2024 the EPA set the first national limits: 4.0 parts per trillion each for PFOA and PFOS, and limits for four others. In May 2025 the agency said it would keep the PFOA and PFOS limits but rescind the rest, and in May 2026 it proposed rules to do that and to let systems request two more years, to 2031, to comply. As of October 2026 those changes are proposals.

Filters. Look for certification to NSF/ANSI Standard 53 (or Standard 58 for reverse osmosis) for the specific contaminant you care about, such as lead or PFOA and PFOS. The EPA cautions that current PFAS certifications do not yet confirm removal down to its new limits. Change cartridges on schedule.

Wells. Private wells are not regulated. Test every year for total coliform bacteria, nitrates, total dissolved solids, and pH, and ask your health department about local concerns such as arsenic, uranium, radon, or PFAS.

Microplastics and chemicals#

Here worry often runs ahead of the evidence. Some concerns are real; the size of the harm is mostly unknown.

• Microplastics. Tiny plastic particles are everywhere, including bottled water (see nutrition). In a 2024 study of 257 people having carotid artery surgery, those with plastic particles in their artery plaque had 4.5 times the risk of heart attack, stroke, or death over about three years. A 2025 study found plastic concentrations in brain tissue were higher in 2024 than in 2016, and higher still in people with dementia. Both are observational, the measurement methods are new, and neither shows that plastics caused the harm Weak.
• BPA. Regulators disagree. In 2023 the European Food Safety Authority cut its tolerable daily intake by about 20,000-fold, to 0.2 nanograms per kilogram of body weight, and concluded that typical exposure is a health concern. The FDA's position is that BPA is safe at current levels in food.
• Phthalates. These plasticizers are in food packaging, vinyl, and fragrances. A 2022 analysis of US national data estimated 90,761 to 107,283 attributable deaths a year among adults 55 to 64, an extrapolation from observational data.
• PFAS in products. The International Agency for Research on Cancer classifies PFOA as carcinogenic to humans and PFOS as possibly carcinogenic. PFOA is no longer made in the US; most nonstick pans use PTFE, a different fluorinated plastic. Use them on low to medium heat, never heat them empty, and replace them when scratched or flaking; stainless steel and cast iron avoid the question.
• Black plastic utensils. A widely shared 2024 study found flame retardants, likely from recycled electronics, in 85% of black plastic household products it analyzed; the paper was corrected twice in 2025. Swapping them for wood or steel is easy either way.

Low-cost steps: do not microwave food in plastic, use glass or steel for hot food and drinks, filter drinking water (see above), choose fragrance-free products where you can, and ventilate when cooking and cleaning.

Noise and extreme heat#

Noise#

Loud noise damages hearing gradually and permanently. NIOSH sets its workplace exposure limit at 85 dBA averaged over eight hours and halves the safe time for every 3 dBA above that, so 100 dBA is safe for only about 15 minutes. Carry earplugs to concerts, keep earbud volume moderate, and use earmuffs with power tools. Chronic traffic and aircraft noise is also associated with high blood pressure, heart attack, and stroke, especially at night. See eyes, ears, teeth, and skin for hearing tests and hearing aids.

Extreme heat#

Heat-related deaths in the US more than doubled from 1999 to 2,325 in 2023. The people most at risk are adults 65 and older, infants and young children, people with heart, lung, or kidney disease, outdoor workers, and athletes (CDC). Many prescription and over-the-counter medications impair the body's ability to cool itself.

Heat stroke is an emergency; body temperature can reach 106°F (41°C) within 10 to 15 minutes. On hot days, spend the hottest hours somewhere air-conditioned, drink water before you are thirsty, check on older relatives, and never leave anyone in a parked car. Sun protection is covered in eyes, ears, teeth, and skin.

Action plan#