Knowledge Center

Many people, after purchasing and drinking bottled water, habitually reuse the plastic bottles that held the water for convenience—to carry drinking water in their cars or while working outside. However, this is not a good idea.Generally speaking, polyethylene terephthalate (PET), a material found in some plastic bottles and containers, has been found in recent studies and inspections to contain a potential carcinogen: diethylhydroxylamine (DEHA). For safety reasons, these plastic bottles or containers should be used only once. If longer-term use is necessary, one week is the absolute limit, and they should not be used to hold hot drinking water or food.Repeated washing and rinsing of plastic bottles or containers can cause the plastic to break down and release carcinogens, which dissolve into the water inside and, when ingested, can cause irreversible, permanent damage to the body.When selecting a water bottle, choose reusable plastic bottles, glass bottles, or bottles with stainless steel liners. Be sure to wash them thoroughly after each use to prevent bacteria from breeding in warm, damp bottles.When purchasing water bottles, consumers should make rational choices based on logic and science, and avoid blindly trusting exaggerated claims in advertisements about health, safety, or “magical” designs.By Michael Chiu, MWS, CIPreviously published in Ming Pao Daily News - Updated and Revised in 2026

Diarrheal disease remains one of the world's major public-health problems. WHO estimates that nearly 1.7 billion cases of childhood diarrheal disease occur every year, and approximately 443,832 children under the age of five die from diarrhea each year. Diarrheal disease is particularly serious in low- and middle-income countries, where access to safe drinking water, sanitation, and hygiene remains a challenge.Unsafe drinking water is an important source of diarrheal disease. In 2022, at least 1.7 billion people worldwide were using a drinking-water source contaminated with feaces. Microbial contamination of drinking water can transmit diseases including diarrhea, cholera, dysentery, typhoid, and polio. Improving access to safe drinking water, adequate sanitation, and good hygiene can substantially reduce the risk of diarrheal disease. Important preventive measures include using safe drinking water, washing hands with soap, maintaining good food hygiene, and using appropriate sanitation.Household water treatment can also be an important public-health intervention, particularly for people who rely on contaminated or unreliable water supplies. Treatment methods can include filtration, boiling, chlorination, and other technologies designed to reduce microbial contamination. WHO continues to evaluate household water-treatment technologies for their ability to remove or inactivate pathogens.Safe drinking water is therefore not simply a matter of taste or convenience. Where drinking water is contaminated or unreliable, improving water safety can play an important role in preventing disease, particularly among young children.By Michael Chiu, MWS, CIPreviously published in Ming Pao Daily News - Updated and Revised in 2026

When the weather changes or seasons shift, many people experience a runny nose, nasal congestion, itchy eyes, and a sore throat. Often, they assume they have simply caught a cold and overlook the possibility that these may be allergy symptoms. Allergies and colds can produce similar symptoms, but distinguishing between them can help people choose the appropriate treatment.Allergy symptoms include: a runny nose (usually with thin, clear discharge), sneezing, nasal congestion, wheezing, and itchy eyes, nose, or throat. Allergy symptoms may also include watery eyes and usually do not cause a fever.Causes/Duration: These symptoms are commonly caused by exposure to allergens such as pollen, dust mites, mold, animal dander, and certain chemicals or other substances. Symptoms can continue as long as a person remains exposed to the allergen. Seasonal allergies are particularly common during periods when pollen levels are high.Symptoms of a common cold caused by a virus can include: a runny or stuffy nose, sneezing, sore throat, cough, mild fever, headache, and feelings of tiredness or weakness. Nasal discharge may become thicker or change color during a cold, but the color of mucus alone cannot reliably distinguish a cold from an allergy.Causes/Duration: Cold symptoms usually develop about 1–3 days after exposure to a respiratory virus and commonly improve within about 7–10 days, although a cough or other symptoms may last longer.If symptoms are severe, persistent, repeatedly interfere with daily activities, or include significant difficulty breathing, medical advice should be sought.By Michael Chiu, MWS, CIPreviously published in Ming Pao Daily News - Updated and Revised [...]

When considering the purchase of an air purification system, consumers should understand the different technologies available, what pollutants each technology can remove, and the limitations of the system. A useful air purifier should be selected according to the particular indoor-air problem, the size of the room, the amount of air it can effectively clean, and the manufacturer's maintenance requirements. No single air-cleaning technology removes every type of indoor pollutant.Some air purifiers use ionization or other technologies that electrically charge particles. These devices can cause airborne particles to become charged and either collect on surfaces or be captured by a collection system. However, some ion-generating air cleaners can also produce ozone as a by-product. Ozone is itself an air pollutant and can irritate the lungs and worsen respiratory symptoms. For this reason, consumers should be cautious about air cleaners that intentionally generate ozone or produce significant ozone as a by-product. The U.S. Environmental Protection Agency does not recommend the use of ozone generators in occupied spaces for controlling indoor air pollution.Ionization technology should also not be confused with ordinary mechanical filtration. An ionizer may cause particles to settle onto walls, floors, furniture, and other surfaces rather than actually removing them from the indoor environment. The performance of individual products varies considerably, so claims that an air cleaner “kills germs” or “purifies the air” should be evaluated carefully.Mechanical filtration is one of the better-established methods for removing airborne particles. High-Efficiency Particulate Air (HEPA) filters are designed to remove very small particles from an airstream with high efficiency. [...]

The human body contains a large amount of water, and water is essential for maintaining normal body functions. Water helps regulate body temperature, transport nutrients, remove waste, and keep our organs and tissues functioning properly. Therefore, drinking enough fluids is essential for maintaining good health.Tips for Drinking Water:Drink water regularly throughout the day. There is no universal requirement to drink exactly eight 8-ounce glasses of water every day. The amount of fluid a person needs varies depending on age, body size, diet, activity level, climate, and other factors. People who exercise or spend time in hot weather generally need more fluids.Don't wait until you are extremely thirsty to drink, particularly during exercise or hot weather. Thirst is an important signal that your body needs fluids, but during strenuous activity or high temperatures, fluid losses can occur quickly.Drink plenty of water throughout the day. Bring a water bottle to work or school and keep water readily available as a reminder to drink regularly.Water is an excellent choice for hydration. Alcohol can increase fluid loss, particularly when consumed in large amounts. Normal amounts of caffeinated beverages, however, generally still contribute to daily fluid intake and do not automatically cause dehydration.Drink enough water during exercise to replace fluids lost through sweating, especially during prolonged or strenuous activity and hot weather. During long periods of intense exercise, electrolytes may also need to be replaced.Drink enough fluids throughout the day and adjust your intake according to your needs. There is no general need to drink a large amount of water [...]

Many people wonder whether they should clean their home's air ducts every year. The answer varies from home to home.Air duct cleaning companies, from a business perspective, may recommend regular cleaning to prevent or alleviate allergies or asthma. In reality, there are many factors that contribute to poor indoor air quality and related health problems. While air duct cleaning may sometimes be helpful, it is not generally considered a comprehensive solution for improving indoor air quality.The U.S. Environmental Protection Agency (EPA) does not recommend routine cleaning of air ducts. Cleaning may be appropriate when there is substantial visible mold growth inside hard-surface ducts, when the ducts are infested with insects or rodents, or when substantial amounts of dust and debris have accumulated and are actually being released into the home. The EPA notes that there is currently no evidence that simply having dirty air ducts increases the amount of dust in a home or that duct cleaning prevents health problems.Residents may have difficulty determining the condition of their ductwork because much of the system is inaccessible. However, ordinary household dust should not be assumed to be accumulating in ducts in quantities that make duct cleaning necessary. Dust mites and their waste can contribute to allergies and asthma, but they primarily live in household furnishings such as bedding, carpets, and upholstered furniture rather than inside air ducts.Many people mistakenly believe that indoor dust is routinely distributed throughout the home by the air ducts. In reality, dust enters and accumulates in homes from many sources, including outdoor [...]

Caffeine is a central nervous system stimulant that can temporarily reduce drowsiness and increase alertness. Caffeine-containing products such as coffee, tea, soft drinks, chocolate, and energy drinks are extremely popular, making caffeine one of the most widely consumed psychoactive substances in the world.Coffee and tea are two of the most common natural sources of caffeine, although the amount varies considerably depending on the type of product and how it is prepared. Caffeine is also found naturally in ingredients such as cocoa, guarana, and yerba mate. Energy drinks and other foods may also contain added caffeine.Unlike some other central nervous system stimulants, the effects of caffeine are temporary. For most people, moderate caffeine consumption can increase alertness and attention. However, sensitivity varies from person to person, and consuming caffeine later in the day can interfere with sleep.Regular caffeine consumption can cause the body to become accustomed to caffeine. If someone who regularly consumes caffeine suddenly stops, withdrawal symptoms such as headache, fatigue, irritability, and difficulty concentrating may occur. These symptoms are generally temporary, and gradually reducing caffeine intake can make withdrawal easier.Research has found an association between caffeine consumption and a lower risk of developing Parkinson's disease in some populations. However, this does not establish that caffeine prevents Parkinson's disease, and more research is needed to understand the relationship.Excessive caffeine intake can cause symptoms such as nervousness, irritability, anxiety, insomnia, headache, increased heart rate, heart palpitations, and stomach upset. Health Canada recommends a maximum daily caffeine intake of 400 milligrams for adults 18 and older. The [...]

Laser printers and photocopiers can release small amounts of pollutants into indoor air during operation. Older laser printers, in particular, could produce ozone during the printing process. Therefore, it is better not to place a printer immediately beside a person's desk, especially in a poorly ventilated room.Laser printers have become common in homes and offices. During printing, toner is transferred to the paper and then fixed to the paper by heat and pressure. The printing process can release particles and volatile organic compounds (VOCs), while some older laser-printer technologies could also generate ozone.Ozone is a respiratory irritant, and exposure to elevated concentrations can cause coughing, throat irritation, breathing difficulties, and other respiratory effects. However, the amount of ozone produced varies considerably between printer models. Studies by the National Institute for Occupational Safety and Health (NIOSH) found that older printers using corona-wire technology could produce significantly more ozone, while newer printers using charged-roller technology produced very little ozone.Laser printers and copiers can also contribute to indoor particulate matter and VOCs. The U.S. Environmental Protection Agency (EPA) recommends good ventilation when operating printers and copiers and notes that increased filtration and ventilation can reduce exposure to indoor particles from these devices.For better indoor air quality, place printers and copiers in well-ventilated areas rather than directly beside people who spend many hours at a desk. Regular maintenance should also be performed according to the manufacturer's instructions. If a printer produces a strong or unusual odor, excessive dust, or other noticeable emissions, improving ventilation and having the equipment inspected [...]

A parasite is an organism that lives in or on another organism, known as a host, and obtains nutrients or other benefits from the host. Parasitic organisms can cause harm to their hosts, although the effects vary depending on the type of parasite and the host.Parasites that infect humans can enter the body through contaminated food or water, insect bites, contact with contaminated soil or surfaces, or direct contact with an infected person or animal. Some parasites can live in the intestines, while others can infect tissues, blood, or other parts of the body.However, it is impossible for humans to completely isolate themselves from parasites. According to the World Health Organization, parasitic infections remain an important global health problem, particularly in tropical and subtropical regions where inadequate sanitation, unsafe water, poor hygiene, and limited access to health care can increase the risk of infection. Diseases such as lymphatic filariasis, schistosomiasis, and soil-transmitted worm infections affect millions of people worldwide.Parasites can cause a wide range of health problems, including abdominal pain, diarrhea, anemia, malnutrition, fever, and damage to organs or tissues. Lymphatic filariasis, for example, is caused by microscopic parasitic worms transmitted through mosquito bites and can lead to severe swelling and enlargement of affected parts of the body.There may also be a beneficial side to the study of parasites. Researchers have investigated whether certain parasitic worms, known as helminths, or substances produced by them could help regulate an overactive immune system. This research has led to studies involving conditions such as inflammatory bowel disease and [...]

Air conditioning, commonly abbreviated as “AC,” is a system or appliance that removes heat from an indoor space, typically through a refrigeration cycle, and transfers that heat outdoors. Modern air-conditioning systems can also dehumidify and filter indoor air. When heating, ventilation, and air conditioning are considered together, the overall system is commonly referred to as HVAC (heating, ventilation, and air conditioning).Air conditioning has become increasingly widespread around the world, particularly in regions with hot or humid climates. In East Asia, it is now common in countries and regions including Japan, South Korea, mainland China, Hong Kong, and Taiwan. China has experienced especially rapid growth in air-conditioning ownership and cooling demand. The International Energy Agency (IEA) estimates that nearly 90% of households in Japan and the United States have an air conditioner, while air-conditioning ownership in China has risen substantially over the past decade.Residential systems in East Asia commonly include room air conditioners, ductless mini-split systems, and multi-split systems. These systems can provide efficient cooling to individual rooms or several rooms without requiring the large duct networks used by many North American central-air systems. As incomes, access to electricity, and demand for thermal comfort have increased, air conditioning has also expanded in Southeast Asia. Nevertheless, ownership remains considerably lower there than in countries such as Japan and the United States, despite the region's substantial need for cooling. The IEA projects continued rapid growth in residential air-conditioning use in Southeast Asia. In the United States, air conditioning is now widespread across most regions rather than being concentrated [...]