Ask Tufts Experts

I use a water filter at home to get rid of minerals and sediment in my tap water. But does it also remove fluoride? I’m concerned about my family’s teeth.

No need to worry. Both faucet-mount water filters and pitcher filters like Brita remove hardly any fluoride. Very small amounts of the mineral may be taken out of the water when a filter is brand new, says George Acs, DMD, MPH, a spokesperson for the American Academy of Pediatric Dentistry. But the amount is negligible. Other home water treatment systems, including distillation and reverse osmosis units, do remove significant levels of fluoride, however. Regular use of water filtered with these devices can put children at risk for tooth decay.

Is there a point at which it’s too cold to exercise outdoors?

There’s no specific cut-off point, reports John Castellani, PhD, of the US Army Research Institute of Environmental Medicine. The key is to prevent your body temperature from dropping by wearing clothing that traps body heat as well as transfers perspiration away from the body. Experts recommend dressing in three layers: an under-layer that doesn’t absorb water (look for synthetic materials like polypropylene); an insulating middle layer, like fleece or wool; and a water- or wind-resistant top layer. Before venturing out, check the wind chill factor. Areas of the body that are difficult to cover, like the cheeks, earlobes, and nose, can be at risk for frostbite once the wind chill goes below minus-20 degrees Fahrenheit.