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Scientists are ramping up research on the possible health effects of a large group of common but little-understood chemicals used in water-resistant clothing, stain-resistant furniture, nonstick cookware and many other consumer products. Per- and polyfluoroalkyl substances are generally referred to by their plural acronym, PFAS. PFAS are resistant to water, oil and heat, and their use has expanded rapidly since they were developed by companies in the mid-20th century. Today, PFAS' nonstick qualities make them useful in products as diverse as food wrappers, umbrellas, tents, carpets and firefighting foam. The chemicals are also used in the manufacture of plastic and rubber and in insulation for wiring. (Hersher, 4/22)

When Yondje Choi was told she would need a face mask for an upcoming trip to South Korea, Ms. Choi, a 31-year-old New Yorker, was shocked. “I knew air pollution is a major problem in Beijing, but I didn’t know it was this bad here,” she said last month in Seoul. While China takes a bulk of the heat when it comes to unhealthy levels of air quality, air pollution is a major issue throughout Asia and beyond, even to Europe and North America. Without research and self-care, even short-term visitors may feel the effects. Here are some precautions you can take to help you breathe easier. (Yoon, 4/21)