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Editor's Note: This article has been translated and editorially updated for accuracy and to reflect current Canadian drinking-water guidance. Some historical information has been retained from the original publication for context. When I first came to Canada, I was told by long-time residents that Canadian tap water was safe to drink directly from the tap. Public drinking fountains are common, and many people regularly drink tap water at home, at school, and in other public places. But can we really be confident that tap water is always safe at the point where we drink it? Reports of elevated lead levels in drinking-water outlets at Canadian schools and homes have raised important questions about the difference between the quality of treated municipal water and the quality of water that ultimately comes out of an individual tap. Elevated Lead Levels Found at Some BC Schools Historical testing in British Columbia found elevated lead levels at a number of drinking-water outlets in schools. According to reporting by the Vancouver Sun, testing carried out across 60 school sites in BC during 2016 and 2017 involved approximately 10,000 drinking-water sources and 15,000 tests. Some samples contained lead concentrations above the drinking-water guideline in effect at the time. The reported results varied considerably between locations. In some individual outlets, very high lead concentrations were detected. For example, testing reported at Walter Lee Elementary School in Richmond found one drinking-water sample with a lead concentration more than 300 times the applicable standard at the time. Other individual samples reported in [...]

Pollution (environmental pollution) refers to the introduction of substances or forms of energy into the environment that can cause harmful effects to ecosystems, wildlife, or human health. Pollution can be caused by human activities as well as natural processes. Even when there is no immediate visible harm, environmental contamination can have harmful long-term effects. For example, nitrogen oxides released into the atmosphere can contribute to the formation of ground-level ozone and other components of photochemical smog when they react with other pollutants in the presence of sunlight.Pollution occurs on both regional and global scales. In the past, attention was focused primarily on regional pollution. For example, burning coal produces particulate matter and sulfur dioxide, which can harm human health and contribute to acid rain. However, scientific research has shown that pollution can also have effects across national borders and around the world. Burning coal also produces carbon dioxide, a greenhouse gas that contributes to climate change when emitted in large quantities.Whether something constitutes pollution depends on its effects on the environment and human health. For example, excess nitrogen and phosphorus from agriculture, wastewater, and other human activities can enter rivers, lakes, and coastal waters. Excess nutrients can promote abnormal algae growth, resulting in harmful algal blooms and reduced oxygen levels that can damage aquatic ecosystems.Pollution is generally classified into air pollution, water pollution, soil or land pollution, and pollution from chemicals and waste. Other forms, including marine pollution, noise pollution, light pollution, and thermal pollution, can also affect human health and ecosystems.Major sources of pollution [...]

To ensure clean drinking water or high-quality water for cooking, many households install water filters. However, before installation, you should consider the factors listed below to avoid facing charges or criminal liability. Select an appropriate water filterHire a certified installer or water quality specialist to handle the installationInspect the installed filter regularly; perform regular disinfection and maintenance proceduresReplace filter media and cartridges regularly. Many countries and cities have laws regulating and prohibiting citizens from installing water filters, as improper installation, lack of maintenance, failure to perform repairs, or improper replacement of filter media or cartridges may directly or indirectly contaminate the public water supply system (since household water pipes are interconnected) and endanger public health. Therefore, consumers should pay attention to the key points provided above when installing water filters to avoid unnecessary losses or, worse still, legal consequences. By Michael Chiu, MWS, CIPreviously published in Ming Pao Daily News - Updated and Revised in 2026

According to scientific research, the greenhouse effect refers to the natural process by which certain gases in the atmosphere absorb and re-emit infrared radiation, warming the Earth's surface and lower atmosphere. The natural greenhouse effect makes Earth habitable; however, human activities have increased the concentration of greenhouse gases in the atmosphere, strengthening the greenhouse effect and causing global warming.The greenhouse effect is primarily associated with greenhouse gases such as carbon dioxide, methane, nitrous oxide, and water vapor. These gases absorb some of the infrared radiation emitted by the Earth's surface and re-emit it in different directions, including back toward the surface. As greenhouse gas concentrations increase, more energy is retained within the climate system, causing the Earth's average temperature to rise.Solar radiation consists primarily of shorter-wavelength radiation, while the Earth's surface emits energy primarily as longer-wavelength infrared radiation. The atmosphere is relatively transparent to much of the incoming solar radiation but absorbs some of the infrared radiation emitted by the Earth's surface.During the day, sunlight reaches the Earth, and some of its energy is reflected back into space while the rest is absorbed by the atmosphere, land, and oceans.The Earth's surface continuously emits infrared radiation. Some of this radiation passes through the atmosphere and escapes into space, while greenhouse gases absorb and re-emit some of it. This process helps keep the Earth's surface warmer than it would otherwise be.The greenhouse effect is sometimes compared with the glass of a greenhouse, although the actual atmospheric process is different. Without the natural greenhouse effect, Earth would be [...]

Global warming refers to the long-term rise in the average temperature of the Earth's atmosphere and oceans. It primarily refers to the warming observed since the pre-industrial period, which is mainly caused by human activities and the increasing concentration of greenhouse gases in the atmosphere.During the 20th century, the global average temperature increased significantly. Since the pre-industrial period (1850–1900), the global surface temperature has risen by approximately 1.1 degrees Celsius. Scientific evidence shows that human activities, particularly the burning of fossil fuels and the resulting increase in greenhouse gas emissions, are the principal cause of the warming observed since the mid-20th century.The rising concentrations of carbon dioxide and other greenhouse gases are the primary human-induced factors contributing to global warming. Activities such as burning fossil fuels, deforestation, and agriculture increase greenhouse gas concentrations and intensify the greenhouse effect.Since the Industrial Revolution, carbon dioxide concentrations in the atmosphere have increased substantially. Although plants and the oceans absorb a significant portion of the carbon dioxide released by human activities, these natural processes do not remove all of the additional carbon dioxide, and atmospheric concentrations have continued to rise.Global warming can lead to many other changes, including rising sea levels and changes in the amount and patterns of rainfall and snowfall. Climate change is also contributing to changes in extreme weather, including more frequent and intense heat waves and heavier precipitation in many regions. Other consequences include changes in crop yields, retreating glaciers and ice sheets, changes in river flows, shifts in the distribution of plant and animal [...]

Drinking enough water is the best way to address the problem of excess water retention in the body. When water intake decreases, the body perceives this dehydration as a survival warning and begins to store water. Water is stored outside the cells (in the spaces surrounding them), which is why swelling often appears in the hands, feet, and inner thighs. Diuretics can provide a temporary solution to edema by forcing the body to expel stored water along with some essential nutrients. However, the body recognizes this loss of water as a survival threat and immediately replenishes the lost fluids. As a result, the swelling quickly returns. The best way to overcome the problem of excessive water retention is to provide the body with the ample amount of water it needs. Only then can the body release the accumulated water. If your body is retaining too much water, excessive salt intake may be the culprit, as your body can only tolerate a certain concentration of sodium. Therefore, the more salt you consume, the more water your body retains to dilute the salt concentration. However, flushing out excess salt from the body is actually quite simple—just drink plenty of water, and the kidneys will excrete the excess sodium through urination. Overweight individuals need more water than slimmer people because their larger bodies have a heavier metabolic workload. Since we already know that water is key to converting fat into energy, it’s easy to understand why overweight people need more water.Water enables muscles to perform their natural function [...]

In a subsequent report, United Nations experts pointed out that global warming could threaten food security in some countries, particularly in vulnerable tropical and subtropical regions. The report also warned that climate change could increase the frequency and severity of extreme weather events such as heat waves, droughts, heavy rainfall, and floods, creating additional costs that could affect economies around the world.Experts from the United Nations Intergovernmental Panel on Climate Change (IPCC) stated that agriculture worldwide is being affected by climate change, raising concerns about food supplies for the growing global population.Agricultural yields can decline when crops are exposed to higher temperatures, drought, and other climate extremes. Some higher-latitude regions may experience longer growing seasons or temporary increases in suitability for certain crops, but these potential benefits can be accompanied by increased risks from pests, diseases, and other climate-related stresses.In tropical regions where farming is particularly dependent on rainfall, some crops are already approaching or exceeding their temperature tolerance limits. Further warming, combined with changes in precipitation, drought, and extreme heat, could lead to greater losses in crop production. The IPCC reports that climate change is already affecting food security and that the risks increase with every additional degree of warming.Human activities have released large quantities of carbon dioxide and other greenhouse gases into the atmosphere, causing global temperatures to rise. The IPCC's latest assessments show that continued warming will increasingly affect food production, water supplies, human health, ecosystems, and economies around the world.The economic effects of climate change are difficult to express as a [...]

Air pollution refers to the contamination of the atmosphere by substances that are harmful to human health and the surrounding environment. These substances may be gases, solid particles, or liquid droplets. The air we breathe every day is composed of various chemical substances, with nitrogen being the most abundant element (about 78%), followed by oxygen (about 21%), along with trace gases like argon and carbon dioxide. The composition of each gas is not entirely fixed and can vary slightly over time. If the concentration of pollutants in the air remains low, the impact on human health and the environment will be relatively minor; however, when these pollutants reach dangerous levels, we must find ways to reduce or remove them from the air.Air pollution can be broadly divided into three main categories: chemical pollution (gases and vapors like carbon monoxide or nitrogen oxides), biological pollution (pollen, mold, and airborne pathogens), and particulate matter pollution (PM10 and fine PM2.5 particles). While noise, heat, radiation, and light pollution are sometimes mentioned alongside atmospheric issues, modern environmental science classifies these specifically as physical hazards rather than air contaminants. Generally, the causes of air pollution can be categorized into natural and human-made sources.Natural sources of air pollution include:Volcanic activity releasing sulfur dioxide and ashDust and sand blown from desert regions or areas lacking vegetationGases emitted by biological processes, such as methane released by livestock during digestionSmoke and fine particulate matter produced by wildfiresHuman-made (anthropogenic) air pollution is typically caused by industrial processes and the combustion of fossil fuels, which result [...]

Air pollutants can broadly be classified into gaseous pollutants and particulate matter. In reality, air pollution is a complex mixture of gases, particles, and other substances, and pollutants can affect both outdoor and indoor air. Among the pollutants with the strongest evidence of adverse effects on human health are particulate matter, ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide.Common gaseous pollutants include sulfur dioxide (SO₂) and nitrogen dioxide (NO₂), which are associated with the combustion of fossil fuels and industrial processes. Nitrogen oxides and sulfur dioxide can contribute to the formation of acid deposition. Other important gaseous pollutants include carbon monoxide (CO), a toxic gas produced by incomplete combustion; ground-level ozone (O₃), a major component of photochemical smog; and various volatile organic compounds (VOCs), some of which are toxic or contribute to the formation of ozone.Carbon dioxide (CO₂) is a greenhouse gas and an important driver of climate change, although it is not generally classified as a conventional toxic air pollutant at the concentrations normally found outdoors. Chlorofluorocarbons (CFCs) are also powerful greenhouse gases and, historically, were widely used as refrigerants and in other applications. They are particularly important environmentally because they also destroy stratospheric ozone. International controls under the Montreal Protocol have greatly reduced their production and use.Ozone requires particular attention because its effects depend strongly on where it is found. Ground-level, or tropospheric, ozone is an air pollutant that can irritate and damage the respiratory system and is an important component of smog. In contrast, most atmospheric ozone is found in the stratosphere, [...]

Scale is a hard, grayish-white or yellowish-white deposit commonly found on the inner surfaces of kettles, water heaters, and poorly maintained hot-water systems. Similar deposits can form inside old water pipes, on faucets, shower surfaces, and other areas where hard water evaporates. The type of scale varies depending on the water chemistry and the surface where it forms. The main component of scale deposited on heating elements in water heaters and similar appliances is often calcium carbonate, which can precipitate when hard water is heated. Hard water contains dissolved calcium and magnesium, which are the principal minerals responsible for water hardness. Calcium carbonate is less soluble under many conditions associated with heating, which can cause mineral deposits to form on heated surfaces. As water is heated and some of it evaporates, dissolved minerals can also become more concentrated, increasing the potential for precipitation and scale formation. Calcium and magnesium in hard water can also react with traditional soap, producing an insoluble material commonly known as soap scum. This residue can deposit on bathtubs, sinks, shower walls, glass, and other surfaces. Hard water can also make it more difficult for soap to lather and may require greater amounts of soap or detergent. Soap scum can remain on the skin and hair after washing, although the effects can vary from person to person. Hard water and soap residues may contribute to a feeling of dryness or irritation in some individuals, but hard water itself should not be described as a proven cause of skin inflammation or itching. [...]