Explore each chapter to understand the effort, benefits and context.
This chapter covers three things: accidental and injury deaths from crashes, fires and poisoning; a few vaccines and screening tests backed by particularly strong evidence; and symptoms that deserve a medical check. The numbers under Benefits come from randomized trials, studies following large groups for many years, or official statistics. Costs are the author's rough estimates of market prices in China, offered only for comparison; do not cite them as established figures.
Wearing a seat belt in the front seat cuts your risk of a fatal injury in a crash by roughly half; in the front of a light truck, by about 60%. Among US vehicle occupants killed in 2022 whose belt use was known, half were unbelted.
A helmet with its chin strap fastened lowers a motorcyclist's risk of dying in a crash by about 40% and of head injury by about 70%. Tighten the strap: a helmet resting loosely on your head does not count.
A working smoke alarm can lower the risk of death in a house fire by about 60%. Around four in ten victims were asleep when the fire began; smell alone will not reliably wake you. If you burn coal or use gas indoors in winter, add a carbon monoxide alarm. China recorded about 11,500 carbon monoxide deaths in 2018; in the three winter months, roughly 70% occurred at home.
A compliant hose costs only a few dozen renminbi. China's Regulations on the Administration of Urban Gas require users to replace expired equipment and prohibit unauthorized changes to pipework or removal of gas meters. The same regulations say a gas supplier cannot force you to buy its chosen products or services. You can refuse a door-to-door sales pitch claiming that you “must replace” something through that seller.
In China in 2025 alone, 828 mushroom-poisoning incidents affected 2,165 people and killed 13. That year also brought records of 34 species not previously documented as causing poisoning in China. Silver needles, insect bites and bright colors cannot tell you whether a mushroom is safe.
The source describes bringing e-bikes into corridors or elevators and charging them at home as prohibited by China's high-rise fire-safety rules. Refusing to correct a violation can mean an RMB 500–1,000 fine for non-business users, or RMB 2,000–10,000 for businesses. The bigger issue is a fire blocking your only escape route.
For every 10 mmHg reduction in blood pressure, major cardiovascular problems fall by about 20%, stroke by 27%, heart failure by 28% and death by 13%. Among Chinese adults aged 35–75, 44.7% had hypertension, and only 7.2% of those affected had it controlled.
A blood test costing a few dozen renminbi can detect prediabetes before symptoms appear. The US screening recommendation covers adults aged 35–70 who are overweight or obese, with repeat testing every three years when results are normal.
A 1% increase in average speed raises the risk of a fatal crash by about 4%. There is no reassuring “a little is fine” threshold for drinking and driving: risk starts increasing at very low blood-alcohol levels.
A car seat cuts fatal injury risk in a crash by about 70% for infants under 1 and about half for children aged 1–4. Holding a child does not provide that protection; you cannot hold on securely during sudden braking.
A few dozen renminbi buys a restrictor. In New York, a program combining free window guards for high-risk households with home visits halved reported child falls in one borough over three years. The city later required landlords to fit guards in homes with children. An insect screen can give way when pushed; it is not fall protection.
Wearing a life jacket roughly halves your risk of drowning after falling into water. Drowning remains the leading cause of death among children aged 1–14 in China; rural drowning mortality is about twice the urban rate.
Balance training a few times a week reduces the number of falls in older adults by about 23% and the number of people who fall by 15%. Home safety improvements such as nonslip surfaces and handrails reduce falls by about 20%. Falls are China's leading cause of injury death after 65, and over half happen at home.
The blood test is inexpensive. In a Qidong trial followed for 30 years, people vaccinated at birth had 84% less primary liver cancer and 72% less hepatitis B carriage. Adults without antibodies can complete three catch-up doses over six months for roughly one or two hundred renminbi.
Once tetanus develops, about one in ten patients dies. Deep or soil-contaminated wounds carry the greatest risk. Same-day wound care may cost only a few dozen renminbi; do not wait for swelling.
Among 1.67 million women in Sweden, those vaccinated before 17 later developed invasive cervical cancer at roughly one-eighth the rate of unvaccinated women. Vaccination at 17–30 still roughly halved the rate. Earlier vaccination offers more benefit.
US screening guidance explicitly recommends mammograms every two years for women aged 40–74. For women 75 or older, and for additional ultrasound or MRI in dense breasts, the evidence is considered insufficient. You can decline these as paid extras in routine checkup packages.
In a rural Indian trial, even a single lifetime HPV screening test approximately halved cervical cancer deaths and advanced cancers. The test costs roughly one or two hundred renminbi in China; a negative result supports a five-year interval.
A low-cost fecal occult blood test every year or two reduced colorectal cancer deaths by about 16%; among people who attended at least one round, the reduction was 25%. Inviting people for one colonoscopy reduced their 10-year colorectal cancer incidence from 1.20% to 0.98%.
In a trial of vaccination after a heart attack, one-year mortality fell from 4.9% to 2.9%. People with cardiovascular disease and older adults can get an autumn dose for RMB 50–150 in China.
A phase 3 trial found about 97% protection against shingles, similar across age groups. The drawback is the RMB 3,000–4,000 out-of-pocket price for two doses. What that buys is roughly a 97% reduction in incidence.
In a trial of 84,500 older adults, the 13-valent vaccine prevented about 46% of pneumonia caused by covered strains and 75% of invasive infections, the most serious form. It did not show a benefit against pneumonia from all causes, so it cannot prevent every case.
In a trial from Linqu, Shandong, followed for 22 years, H. pylori eradication treatment roughly halved stomach cancer incidence and cut stomach cancer deaths by about 40%. Testing costs roughly one or two hundred renminbi, and treatment takes two weeks.
For eligible heavy smokers, annual low-dose CT reduced lung cancer deaths by 20% and overall deaths by 6.7% compared with chest X-rays alone. The tradeoff is further testing and worry after suspicious results.
Evidence for moving potentially lethal items out of reach keeps growing: controls on painkillers were followed by 43% fewer related suicides, and barriers at frequently used jumping sites by an 86% reduction. Avoid stockpiling sleeping pills or pesticides. In China, 12356 is the nationwide psychological support number, available at least 18 hours a day.
All four appear on the Chinese Ministry of Emergency Management's 11-item household emergency checklist. A set costs several hundred renminbi. Studies of safety guidance delivered in people's homes found about a quarter fewer injuries.
After visible blood in urine, about 2.8% of people over 60 and 1.2% of those aged 40–59 were ultimately found to have bladder cancer. That is not a high percentage, but it is high enough to warrant a check—even if the bleeding stops the next day.
Men with erectile dysfunction later developed about 40% more cardiovascular disease and 60% more heart attacks. Relative differences were larger in younger men. Erectile problems often appear before chest pain, so check blood pressure, glucose and lipids instead of masking the problem with self-purchased pills.
Reducing cardiovascular risk factors can improve erectile function itself by an average of 2–3 points on a questionnaire. The scale tops out at 25; scores of 22 or above are considered normal.
Using a condom throughout sex every time reduces heterosexual HIV transmission by more than 70%. “Most of the time” offers much less protection, little different from not using one in the source's account. Condoms also protect against infections such as syphilis and gonorrhea.
HIV testing at a Chinese CDC is free. China's testing-management rules prohibit staff from disclosing your name, address or results. A diagnosis is not a death sentence: people who consistently take treatment and maintain an undetectable viral load do not transmit HIV to sexual partners. A study of over 700 couples and more than 70,000 acts of condomless sex found no within-couple transmission.
Nearly half of interviewed suicide-attempt survivors said no more than 10 minutes passed between the first thought and the attempt. Getting through those minutes can matter enormously. Three-quarters had contact with someone during that period but did not necessarily disclose what was happening. Among people treated in hospital after self-harm, about 2% died by suicide within a year and about 7% over follow-up of 9 years or more; the great majority did not later die by suicide.
Paraquat has no antidote; in the cited study, more than four in ten poisoned patients died. It can inflame and scar the lungs and injure the kidneys and liver. After carbon monoxide poisoning, nearly half of patients given ordinary oxygen still had cognitive problems six weeks later; even with hyperbaric oxygen, the proportion was one-quarter.
Only 5.5% of patients admitted to the cited trauma ICU after a fall from height died, but injuries and treatment were substantial. Nearly half had injuries in at least three body regions, over one-third needed a ventilator, and the longest ICU stay was 132 days. Half fell no more than 3 meters. In a separate severe-injury study, fewer than 60% returned to work.
Among carefully screened kidney donors with medical follow-up, the estimated 15-year risk of end-stage kidney disease was about 31 per 10,000, versus 4 per 10,000 among similarly healthy nondonors. Kidney sellers do not have the same screening and follow-up. Six years after selling, 86% in one survey reported worse health and three-quarters were still in debt.
Radiation has no smell, color or temperature, and many sources look like ordinary metal. Appearance cannot establish safety. Encounters are extremely rare—fewer than one incident annually per 10,000 sources—but the consequences can be irreversible. In Brazil in 1987, people dismantled an abandoned clinic's radiotherapy equipment as scrap; four people died.