Health impact of air pollution

Since the onset of the industrial revolution, there has been a steady change in the composition of the atmosphere mainly due to the combustion of fossil fuels used for the generation of energy and transportation.

Air pollution is a major environmental health problem affecting the developing and the developed countries alike. The effects of air pollution on health०২੨੩৩ are very complex as there are many different sources and their individual effects vary from one to the other. It is not only the ambient air quality in the cities but also the indoor air quality in the rural and the urban areas that are causing concern. In fact in the developing world the highest air pollution exposures occur in the indoor environment. Air pollutants that are inhaled have serious impact on human health affecting the lungs and the respiratory system; they are also taken up by the blood and pumped all round the body. These pollutants are also deposited on soil, plants, and in the water, further contributing to human exposure. As you read on you can learn about health impacts of specific air pollutant.Sources of air pollution

Air pollutants consist of gaseous pollutants, odours, and SPM, (suspended particulate matter) such as dust, fumes, mist, and smoke. The concentration of these in and near the urban areas causes severe pollution to the surroundings. The largest sources of human-created air pollution are energy generation, transportation, and industries that use a great deal of energy sources. Depending on their source and interactions with other components of the air, they can have different chemical compositions and health impacts. Since these pollutants are generally concentrated in and around urban areas, the outdoor urban pollution levels are far higher than in the rural areas.

Fires are another major source of air pollution and can lead to severe problems if the smoke is inhaled for a period of time. These fires can either be forest fires, oil well fires, burning of leaves in the backyard or as in the case of rural areas, large-scale burning of agricultural waste. Other sources include industries and power plants located in these areas.Impact of air pollution on health

The magnitude of the London fog of 1952, which affected such a large number of people, was the first incident that made people aware of the damage done to the atmosphere due to industrialization. The SPM levels increased manifold and resulted in over 4000 deaths.

Indoor air pollution can be particularly hazardous to health as it is released in close proximity to people. It is stated that a pollutant released indoors is many times more likely to reach the lung than that released outdoors. In the developing countries a fairly large portion of the population is dependent on biomass for their energy requirements. These include wood, charcoal, agricultural residue, and animal waste. Open fires used for cooking and heating are commonly found in the household both in the rural and the urban areas. The stove is often at floor level, adding to the risk of accident and the hygiene factor. In addition, they are often not fitted with a chimney to remove the pollutants. In such households the children and women are most likely to be affected, as they are the group that spends more time indoors. The main pollutant in this environment is the SPM. In fact, death due to indoor air pollution, mainly particulate matters, in the rural areas of India are one of the highest in the world. Many of the deaths are due to acute respiratory infections in children; others are due to cardiovascular diseases, lung cancer, and chronic respiratory diseases in adults. If emissions are high and ventilation is poor, household use of coal and biomass can severely affect the indoor air quality.

Pollutant emissions per meal are also very high compared to those of other fuels. Household use of fossil fuel is also fairly common in the developing countries, particularly coal—both bituminous and lignite. These are particularly damaging as they burn inefficiently and emit considerable quantities of air pollutants. If emissions are high and ventilation poor, then the exposure levels to the gases emitted are far higher. The most harmful of the gases and agents that are emitted are particulate matter, carbon dioxide, polycyclic organic matter, and formaldehyde. The indoor concentrations of these are far higher than the acceptable levels and is cause for concern in rural areas.

Health impact of specific air pollutants

Some of these gases can seriously and adversely affect the health of the population and should be given due attention by the concerned authority. The gases mentioned below are mainly outdoor air pollutants but some of them can and do occur indoor depending on the source and the circumstances.

Tobacco smoke. Tobacco smoke generates a wide range of harmful chemicals and is a major cause of ill health, as it is known to cause cancer, not only to the smoker but affecting passive smokers too. It is well-known that smoking affects the passive smoker (the person who is in the vicinity of a smoker and is not himself/herself a smoker) ranging from burning sensation in the eyes or nose, and throat irritation, to cancer, bronchitis, severe asthma, and a decrease in lung function.Biological pollutants. These are mostly allergens that can cause asthma, hay fever, and other allergic diseases. Volatile organic compounds. Volatile compounds can cause irritation of the eye, nose and throat. In severe cases there may be headaches, nausea, and loss of coordination. In the longer run, some of them are suspected to cause damage to the liver and other parts of the body.Formaldehyde. Exposure causes irritation to the eyes, nose and may cause allergies in some people.Lead. Prolonged exposure can cause damage to the nervous system, digestive problems, and in some cases cause cancer. It is especially hazardous to small children.Radon. A radioactive gas that can accumulate inside the house, it originates from the rocks and soil under the house and its level is dominated by the outdoor air and also to some extent the other gases being emitted indoors. Exposure to this gas increases the risk of lung cancer.Ozone. Exposure to this gas makes our eyes itch, burn, and water and it has also been associated with increase in respiratory disorders such as asthma. It lowers our resistance to colds and pneumonia.Oxides of nitrogen. This gas can make children susceptible to respiratory diseases in the winters.Carbon monoxide. CO (carbon monoxide) combines with haemoglobin to lessen the amount of oxygen that enters our blood through our lungs. The binding with other haeme proteins causes changes in the function of the aff
ected organs such as the brain and the cardiovascular system, and also the developing foetus. It can impair our concentration, slow our reflexes, and make us confused and sleepy.Sulphur dioxide. SO₂ (sulphur dioxide) in the air is caused due to the rise in combustion of fossil fuels. It can oxidize and form sulphuric acid mist. SO₂ in the air leads to diseases of the lung and other lung disorders such as wheezing and shortness of breath. Long-term effects are more difficult to ascertain as SO2 exposure isoften combined with that of SPM.SPM (suspended particulate matter). Suspended matter consists of dust, fumes, mist and smoke. The main chemical component of SPM that is of major concern is lead, others being nickel, arsenic, and those present in diesel exhaust. These particles when breathed in, lodge in our lung tissues and cause lung damage and respiratory problems. The importance of SPM as a major pollutant needs special emphasis as a) it affects more people globally than any other pollutant on a continuing basis; b) there is more monitoring data available on this than any other pollutant; and c) more epidemiological evidence has been collected on the exposure to this than to any other pollutant.

3 Natural ways to Whiten teeth at home

Whiter teeth, like is something that many people in our cosmetically driven world desire today. In fact, Americans spend over $1.4 billion dollars in over-the-counter teeth whitening products every year-that’s a good chunk of money just to achieve a different shade of teeth. I’ll be the first to admit that I’ve tried OTC teeth whitener-I even paid to have my dentist do it once. It worked for a bit, but my teeth got so sensitive I couldn’t stand it. I also felt I really didn’t need to be so obsessed with the color of my teeth that I paid a bunch of money for a bunch of who-knows-what that made my teeth hurt, so I started looking into more natural alternatives. With a bit of patience, I think you can naturally restore whiteness to your teeth. They may not get to be scary sear-out-somebodies-corneas –when-you –smile white, but they’ll appear more like you took good care of your pretty pearly whites rather than just bleaching them like crazy.

Fresh juices are good for health

Whole fruits are great to eat because they have insoluble fibre that helps with digestion. Author and natural medicine expert Dr. Michael T. Murray says as a complement to eating fresh fruits and vegetables, we should also consider drinking fresh juices to get our recommended seven to 10 fruits and veggies a day. Fresh juices are also packed with soluble fibre -- a type of fibre that's been shown to lower cholesterol.

Juice Helps With Digestion 
If you're having digestion problems, drinking fresh juice may help. Murray says since juice is easier for our bodies to digest than whole fruits, we're more likely to get the nutrients we need to help us poop.

Your Body Saves Energy 
There's a reason why your body feels good when you eat healthy foods — and why you feel so tired after eating junk. According to Murray, our bodies use energy to convert the foods we eat into liquids to be absorbed. When you drink juice, your body is essentially skipping this step and saving energy.

More Nutritious Than That Store-Bought Stuff 
Fresh juice contains more vitamins, minerals, and other nutritional compounds like enzymes and flavonoids than the canned or bottled options you find in grocery stores. Store-bought juices also often have added sugar -- an ingredient the World Health Organizations says we should be reducing.

More Antioxidants For Your Body
Homemade juices contain increased antioxidant, antiviral, and anticancer properties, Murray says. One study comparing commercial apple juice with freshly squeezed apple juice found fresh, raw juice had more antiviral compounds than the store-bought versions. Another study found that fresh, raw apple juice and berry juice (especially those made with raspberries and blackberries) had more ellagic acid — an anticancer and antioxidant compound that's stripped from juice when it's processed.

Can It Help You Detox? 
Murray says fresh fruits contain glutathione, a small protein composed of three amino acids which aid our bodies in the detoxification of things like lead and pesticides. Most processed fruit juices, however, do not contain this protein.

It Can Help With Weight Loss 
Studies have found diets containing a high percentage (up to 60 per cent of calories) of uncooked foods are associated with weight loss and lowered blood pressure in overweight individuals. Murray suggests making a juice with two whole apples and 1/2 cup each of raspberries and blackberries to help with weight

Build muscle at your Home

Do push-ups to work your arms and chest, starting with 100 a day. Push-ups are the bread and butter of home workouts. Make sure your form is good to get the most out of it. Your spine should be straight and in line with your butt, which isn't sagging. Your palms are generally a little wider than your shoulders, but you can go wider for a better chest workout and narrower for a better arm workout. In addition, you should mix in incline and decline push-ups for better overall muscle growth.

• Incline push-ups work different muscle heads. To do them, simply plant your arms on a low coffee table or chair so that you're angled up.
• Decline push-ups require your place your feet 1-2 feet above your hands, then performing normal push-ups. Remember to keep your head up and spine straight      Do handstands against the wall to build your shoulders and back. Not for the faint of heart, handstands are nonetheless great multi-muscle workout. To get into position, crouch with your back to the wall. Plant your hands on the ground and "walk" your feet slowly up the wall. From there, use your toes for balance, and slowly lower your head to the ground, pushing back up to complete one rep. Try to get three sets of ten in.
  • If you're too nervous for this, you can cheat with a high table. Place your feet on the table with your thighs and torso hanging over the edge, enough that you can place your hands on the ground. Then do a push-up with your head hanging straight down. This is often called a pike push-up.                   
  • Do dips to work out your arms. For good dips, you'll need a sturdy bench, table, or chair roughly 1-2 feet above the ground. Place your hands behind you on this bench so that your butt is in the air and your knees bent 90 degrees. With your feet firmly on the ground, lower your butt to the ground until your arms are bent at roughly 90 degrees. Push back up. Repeat for three sets of 15-20 reps                                                               
  • Do planks. Planks are a great way to work your entire core, and they are easily adapted for an extra challenge. To do one, get in push-up position. However, instead of placing your palms on the ground, rest on your forearms. Tighten your butt muscles and straighten your spine -- you should be able to rest a broom between your neck and butt. Hold this position for one minute, rest, and repeat two more times.
    • Side planks are when you open your body, resting on one forearm and the outside of the same foot. Again, keep your spine straight by focusing on keeping your butt up.
    • Plank to Push-up: Start in a plank position with your arms shoulder width apart and your feet hip width apart. Move down onto your forearms so that you are now in a forearm plank, then lift yourself back up to a full plank position. Do 12 reps in each set.                      
    • Do crunches to build your abs and core. Crunches are still some of the best possible ab workouts out there, so get working. Lay on your back with your feet planted and your knees bent. Supporting your neck with your hands, raise your shoulders 6-8" off the ground, hold for one second, then slowly lower yourself back down. Immediately bounce back up, keeping your eyes on the sky and making your movements slow and deliberate. Perform 1-200 every day for the best results.
      • Straight Leg sit-up: Lay on your back with your legs extended fully, the reach your arms up towards the ceiling and perform a sit-up, keeping your legs straight. Bring your arms down, trying to touch your toes, and then slowly lower back down. Do 10 reps.
       
    Use a gallon of milk, a heavy book, or home dumbbells to perform basic curls. While the rest of the exercises require little to no equipment, most upper body workouts require some sort of resistance in order to be effective. Once you have a weight you can comfortably hold, try out:
    • Bicep Curls
    • Tricep workouts
    • Shoulder raises. 
      

Build Muscle With Specific exercise

Target your pecs with chest exercises. The bench-press is the most dependable way to gain chest muscle, although there are lots of different exercises for the chest.

• Do push-ups. Combine push-ups with other chest exercises, or do them independently. Keep your arms at shoulder-width when you lower yourself down. The closer your hands are to one another, the more you'll work your triceps.
• For the bench-press, start with a weight that you can lift comfortably. If you are a beginner, try lifting the bar along with 5lbs or 10lbs on each side. With arms at shoulder-width apart, grab onto the bar and slowly lower the bar until it's about to touch the bottom of your chest; push up explosively until your arms are fully extended upwards. Do 8-10 repetitions (reps) like this for three sets (3 x 8), adding additional weight each set.
• Lift weights on the incline bench press. The incline is like the bench press, but the bench is slightly elevated at about 40 degrees. Do 3 x 8. It will be harder to lift the bar on an incline, so start out with less weight than you would on the bench-press    
• Target your triceps with arm exercises. Dips are probably the most effective way to work your triceps, which is the muscle beneath your biceps. You'll need to have strong triceps to bench-press large amounts of weight.
  • To do dips, place your hands at shoulder-width apart on a bench, with your body and feet stretched out in front of the bench. Slowly bend your elbows and lower your body down so that your butt nearly touches the floor. Lift back up with your arms to starting position; repeat, doing 3 x 20.
  • Alternately, you can do a chest dip on a dip machine, grabbing hold of two beams, bending your feet back off the ground, and lowering your body until your knees nearly touch the ground. Lift back up with your arms until they are locked.
  • Do skull crushers. Lay down flat on a bench with a bar. Bend your elbows so that the bar is about a couple inches from your forehead. Slowly push the bar up until your arms are fully extended before bringing the weight back down. Keep your elbows close together. Repeat 3 x 8.
  • Do overhead dumbbell press. Take a dumbbell and carefully lift it over your head so that your forearms, gripping the dumbbell, are horizontal behind you. Lift your forearms into a vertical position above your head, taking care not to hit your head with the dumbbell. Keep your elbows close together. 3 x 8.                                                                                                                   
  • Target your biceps with arm exercises. Dumbbell arm curls are probably the most effective way to improve strength in your biceps. As with all exercises, build muscle by steadily increasing the weight you lift.
    • Do individual arm curls with dumbbells. Sit down on a bench and grab onto a dumbbell on the ground, with your hand in between your thighs. Using your thigh as a fulcrum, lift the dumbbell all the way to the upper chest by curling your arm upward. Switch to the opposite hand and repeat. 3 x 8.
    • Do arm curls on a weighted bar. Standing up, grab hold of a weighted bar with both hands. Let the arms extend all the way down to the thighs. Using only your arms, lift the weight up to your chest by curling your arms upward. 3 x 8.
    • Do pull-ups. Jump onto or grab hold of a horizontal bar that is comfortably taller than you. Lift your legs back so that you are hanging from the bar. With your hands shoulder-width apart, and your palms facing toward you, lift your chin up to the bar using only your arms. 2 x 8.                                                                           Work your quads and hamstrings with squats. Squats are the go-to exercise for building muscle in your legs. Here are three different kinds of squats that will work different parts of your leg muscles.
      • Do standard squats with a weighted bar. Place enough weight on a bar and rack it so that it's a little lower than shoulder height. It should be heavy enough that doing a squat is difficult, but not impossible. If you're a beginner, this may mean using a bar without any weight to start with. Duck under the bar and come up so that the bar fits comfortably between your shoulder blades. Your knees should be slightly bent. Lift the bar up off the rack and move backwards one step. Your legs should be slightly wider than shoulder-length.
        • Slowly bring the weight down by bending your knees. Keep your hips under the bar.
        • Arch your back slightly but keep your torso erect.
        • Bring your butt down as far as you can, keeping the tension on the leg muscles.
        • Exhale deeply and use your legs and hips, not your back, to lift out of the squat. 3 x 10.
      • Do front squats with a weighted bar. Rack a weighted bar at just-below shoulder-level. Come up to the bar from the front, positioning the bar on the front shoulders. Cross your arms over onto the bar and walk it out. Keeping your back straight, bend your legs into a squat, with your hips under the bar. Explode upward and repeat. 3 x 10.
      • Do Belgian squats with a dumbbell. Hold out in front of your chest a dumbbell using both hands. Standing in front of a bench, lift your right leg back so that it's parallel to the floor and resting comfortably on the bench. Bend into a squat using the left leg, so that the right knee almost hits the floor. Explode upward. 3 x 8. Repeat using opposite leg.                                                                                        
      Target abdominal muscles with crunches and core exercises. Your abs define the muscles on your stomach, giving you that chiseled 6-pack look. There are a variety of exercises that work out your abdominals. Here are a couple.
      • Do standard/oblique crunches. Lie down on a mat and position both arms behind your head without locking the hands. Bend your knees so that your feet are flat on the ground. Pushing the small of your back into the ground, slowly roll your shoulders off the ground only a couple of inches (not all the way to your feet). Don't use your momentum to help you up; use slow, regulated movements. Repeat 3 x 20.
        • For oblique crunches, tilt your torso to one side as you lift your shoulders off the ground. Alternate sides after each crunch.
      • Do planks to work the abs and the core. Lie face-down on the floor. Lift yourself up so that your body is still parallel to the floor, with your forearms (flat on the floor) and your toes supporting your weight. Keep your body straight and hold your position for as long as possible.
       

Walking it off

Walking has it all. Simple and natural, it doesn't require any instruction or skill. It can be a very modest form of exercise or it can demand enough skill and intensity to be an Olympic sport. You can walk alone for solitude or with friends for companionship. You can walk indoors on a treadmill or outside in the city or country, at home or away. You can get all the benefits of moderate exercise with a very low risk of injury. And to boot, walking is inexpensive. All things considered, Charles Dickens got it right: "Walk to be healthy, walk to be happy." Exercise burns calories. In the case of walking and running, the calories you burn depend much more on the distance you cover and your body weight than on your pace. This table shows calories burned per mile of walking or jogging on the level for people of varying weights: A hundred or so calories a mile might not seem like much, but they can add up to better weight control. For example, a 2009 study of 4,995 men and women found that the average American gains about 2.2 pounds a year during middle age. But during the 15-year study, people who walked gained significantly less weight than those who didn't; the more walking, the less weight gain. And the benefit was greatest in the heaviest individuals. For example, walking for just 35 minutes a day saved a 160-pound person about 18 pounds of flab over 15 years of aging. Your weight Approximate calories per mile 120 lbs 85 140 lbs 95 160 lbs 105 180 lbs 115 200 lbs 125 220 lbs 135

Exercise burns calories. In the case of walking and running, the calories you burn depend much more on the distance you cover and your body weight than on your pace. This table shows calories burned per mile of walking or jogging on the level for people of varying weights:

A hundred or so calories a mile might not seem like much, but they can add up to better weight control. For example, a 2009 study of 4,995 men and women found that the average American gains about 2.2 pounds a year during middle age. But during the 15-year study, people who walked gained significantly less weight than those who didn't; the more walking, the less weight gain. And the benefit was greatest in the heaviest individuals. For example, walking for just 35 minutes a day saved a 160-pound person about 18 pounds of flab over 15 years of aging                                                 

Walking has it all. Simple and natural, it doesn't require any instruction or skill. It can be a very modest form of exercise or it can demand enough skill and intensity to be an Olympic sport. You can walk alone for solitude or with friends for companionship. You can walk indoors on a treadmill or outside in the city or country, at home or away. You can get all the benefits of moderate exercise with a very low risk of injury. And to boot, walking is inexpensive. All things considered, Charles Dickens got it right: "Walk to be healthy, walk to be happy."

Walking: your steps to Health

Every parent knows that a child's first step is a landmark event. It takes many months for that halting step to develop into a sturdy gait, but as toddlers become walkers, they open the door to independence, exploration, and, eventually, productivity. And just as walking is a signal achievement for each person, the two-footed upright gait is a banner accomplishment for our species. In fact, walking is one of the things that distinguishes man from all other animals.

Walking is an automatic, intrinsic human function, and it serves many practical roles. Strange as it seems, though, modern man appears determined to walk as little as possible. Not many men would walk five miles to work — but remarkably few choose to walk even a half mile to a friend's house or neighborhood store. And it's not just a question of walking for transportation; moving walkways whisk us through airports, and elevators and escalators lure many able-bodied men away from stairways. If the Segway "walking" machine ever catches on, walking will suffer yet another setback.

Walking doesn't get the respect it deserves, either for its health benefits, its value for transportation, or its role in recreation.

"But it's not aerobic"

Ever since the 1970s, the aerobic doctrine has dominated the discussion of exercise and health. In a scientific update of your high school coach's slogan "no pain, no gain," the doctrine holds that the benefits of exercise depend on working hard enough to boost your heart rate to 70% to 85% of its maximum, sustaining that effort continuously for 20 to 60 minutes, and repeating the workout at least three times a week.

Aerobic exercise training is indeed the best way to score well on a treadmill test that measures aerobic capacity. It is excellent preparation for athletic competition. And it's great for health. But intense workouts carry a risk for injury, and aerobic exercise is hard work. Although the aerobic doctrine inspired the few, it discouraged the many.

Running is the poster boy for aerobic exercise. With some preparation and a few precautions, it really is splendid for fitness and health. But it's not the only way to exercise for health. Perhaps because they've seen so many hard-breathing, sweat-drenched runners counting their pulse rates, ordinary guys often assume that less intense exercise is a waste of time. In fact, though, moderate exercise is excellent for health — and walking is the poster boy for moderate exercise.

Exercise guidelines The benefits of physical activity depend on three elements: the intensity, duration, and frequency of exercise. Because walking is less intensive than running, you have to walk for longer periods, get out more often, or both to match the benefits of running. As a rough guide, the current American Heart Association/American College of Sports Medicine standards call for able-bodied adults to do moderate-intensity exercise (such as brisk walking) for at least 30 minutes on five days each week or intense aerobic exercise (such as running) for at least 20 minutes three days each week. That makes running seem much more time-efficient — but if you factor in the extra warm-ups, cool-downs, and changes of clothing and shoes that runners need, the time differences narrow considerably. Add the time it takes to rehab from running injuries, and walking looks pretty good. Mix and match to suit your health, abilities, personal preferences, and daily schedules. Walk, jog, bike, swim, garden, golf, dance, or whatever, as long as you keep moving. Remember that Einstein himself explained, "Life is like riding a bicycle. To keep your balance, you must keep moving."

Walking to health

Hundreds of medical studies show that regular exercise is good for health — very good, in fact. But many of these studies lump various forms of exercise together to investigate how the total amount of physical activity influences health. It's important research, but it doesn't necessarily prove that walking, in and of itself, is beneficial.

More than 2,400 years ago, Hippocrates said, "Walking is a man's best medicine." To find out if he was right, two scientists from University College London performed a meta-analysis of research published between 1970 and 2007 in peer-reviewed English-language journals. After sifting through 4,295 articles, they identified 18 studies that met their high standards for quality. In all, these studies evaluated 459,833 participants who were free of cardiovascular disease when the investigations began. Each of the studies collected information about the participants' walking habits along with information about cardiovascular risk factors, including — in most studies — age, smoking, and alcohol use and, in many cases, additional health data as well. The participants were tracked for an average of 11.3 years, during which cardiovascular events (angina, heart attack, heart failure, coronary artery bypass surgery, angioplasty, and stroke) and deaths were recorded.

The meta-analysis makes a strong case for walking. In all, walking reduced the risk of cardiovascular events by 31%, and it cut the risk of dying during the study period by 32%. These benefits were equally robust in men and women. Protection was evident even at distances of just 5½ miles per week and at a pace as casual as about 2 miles per hour. The people who walked longer distances, walked at a faster pace, or both enjoyed the greatest protection.

This meta-analysis included studies from seven countries on three continents. At the risk of being chauvinistic, here is a brief summary of three Harvard studies of walking and cardiovascular health:

• Among 10,269 male graduates of Harvard College, walking at least nine miles a week was linked to a 22% lower death rate.
• Among 44,452 male health professionals, walking at least 30 minutes a day was linked to an 18% lower risk of coronary artery disease.
• Among 72,488 female nurses, walking at least three hours a week was linked to a 35% lower risk of heart attack and cardiac death and a 34% lower risk of stroke.

Extra steps

All 18 studies in this 2008 British meta-analysis are observational studies. As such, each investigation began with a defined group of healthy volunteers (called a cohort) and then observed them over a time period that averaged 11.3 years to see if people who walked enjoyed a reduced risk of cardiovascular disease and a lower rate of death. The results all provide a strong recommendation for walking; however, observational studies are less conclusive than randomized clinical trials. But one clinical trial of walking adds extra weight to the other research. A 10-year study of 229 postmenopausal women randomly assigned the volunteers to walk at least one mile a day or to continue normal activities. At the end of the trial, the walkers enjoyed an 82% lower risk of heart disease.

All 459,833 participants covered by the meta-analysis were free of cardiovascular disease when they enrolled in the 18 studies. But can walking help people who already have heart disease? Randomized clinical trials of cardiac rehabilitation say the answer is yes. A meta-analysis of 48 trials in 8,946 patients showed that moderate exercise — typically walking or riding a stationary bicycle for 30 minutes three times a week — produced a 26% reduction in the risk of death from heart disease and a 20% reduction in the overall death rate.

How walking works

The cardiovascular benefits of walking are biologically plausible; like other forms of regular moderate exercise, walking improves cardiac risk factors such as cholesterol, blood pressure, diabetes, obesity, vascular stiffness and inflammation, and mental stress. And if cardiac protection and a lower death rate are not enough to get you moving, consider that walking and other moderate exercise programs also help protect against dementia, peripheral artery disease, obesity, diabetes, depression, colon cancer, and even erectile dysfunction.

Ready, set, walk.

Walking vs. running Walking is not simply slow running; competitive racewalkers can zip by recreational joggers. The difference between the two is not based on pace. At any speed, walkers have one foot on the ground at all times, but runners are entirely airborne during some part of every stride. As the pace increases, the percentage of each stride that is airborne increases; competitive runners have "hang times" of about 45%. What goes up must come down. That's why running is a high-impact activity. Each time they land, runners subject their bodies to a stress equal to about three times their body weight. In just one mile, a typical runner's legs will have to absorb more than 100 tons of impact force. It's a testament to the human body that running can be safe and enjoyable. At the same time, though, it's a testament to the force of gravity that walkers have a much lower (1% to 5%) risk of exercise-related injuries than runners (20% to 70%).

Blood Pressure

Blood pressure has gotten a bad rap. Some pressure is essential for circulation. Without it, blood couldn't move from the heart to the brain and the toes and back again. The heart provides the driving force — each contraction of the left ventricle, the heart's main pumping chamber, creates a wave of pressure that passes through all the arteries in the body. Relaxed and flexible arteries offer a healthy amount of resistance to each pulse of blood.

But too much of a good thing is a bad thing. Arteries that are tensed, constricted, or rigid offer more resistance. This shows up as higher blood pressure, and it makes the heart work harder. This extra work can weaken the heart muscle over time. It can damage other organs, like the kidneys and the eyes. And the relentless pounding of blood against the walls of arteries causes them to become hard and narrow, potentially setting the stage for a heart attack or stroke.

Most people with high blood pressure (known medically as hypertension) don't know they have it. Hypertension has no symptoms or warning signs. Yet it can be so dangerous to your health and well-being that it has earned the nickname "the silent killer." When high blood pressure is accompanied by high cholesterol and blood sugar levels, the damage to the arteries, kidneys, and heart accelerates exponentially.

High blood pressure is preventable. Daily exercise, following a healthy diet, limiting your intake of alcohol and salt, reducing stress, and not smoking are keys to keeping blood pressure under control. When it creeps into the unhealthy range, lifestyle changes and medications can bring it down.

Stroke should attack caught to snow

Brain cells need a constant supply of oxygen and nutrients. They are delivered by a network of blood vessels that reach every part of the brain. When something cuts off that supply, brain cells downstream begin to die. The injury that follows is called a stroke.

Most strokes strike when a blood clot becomes lodged in one of the brain's arteries, blocking blood flow. In some cases, the clot forms inside the artery, usually because a cholesterol-filled plaque inside the artery breaks open. This is called a thrombotic stroke. In other cases, a blood clot or a solid mass of debris that originates elsewhere travels to the brain, where it blocks a brain artery. This is called an embolic stroke. A third type of stroke, hemorrhagic stroke, occurs when a blood vessel in the brain bursts.

Since different areas of the brain are responsible for different functions, symptoms of stroke vary. They can be changes in sensation, movement, sight, speech, balance, and coordination. Sometimes a stroke is preceded by one or more transient ischemic attacks (TIAs). These are brief episodes of stroke-like symptoms that last for a few minutes — or possibly up to 24 hours — but that go away on their own.

If you think that you, or someone you are with, is having a stroke, call 911 right away. The sooner you call, the sooner treatment can begin — "time is brain," as emergency room doctors say. The type of treatment depends on the type of stroke that has occurred. If the brain's blood supply is restored quickly and completely, a full recovery with little or no disability is possible. The more widespread the damage, and the greater delay of treatment, the more severe and long-lasting the damage.

Recovery after a stroke depends on how well healthy areas of the brain take over duties that had been performed by the damaged brain tissue. To some extent, especially in children and young adults, recovery is possible because of the brain's ability to compensate for damage in one area by working harder in another — by relying on alternate wiring for some functions or by rewiring around the injured site. When such rewiring isn't possible, rehabilitation techniques can help the brain recover function.

Diabetes

Diabetes occurs when the body has trouble using the sugar it gets from food for energy. Sugar builds up in the bloodstream. High blood sugar can have immediate effects, like blurry vision. It can also cause problems over time, like heart disease and blindness.

There are two main types of diabetes: type 1 diabetes (once called juvenile-onset diabetes) and type 2 diabetes (once called adult-onset diabetes). Both are caused by problems making or using insulin, a hormone that makes it possible for cells to use glucose, also known as blood sugar, for energy.

When you eat, your body breaks down carbohydrates into a simple sugar called glucose. It also produces a hormone called insulin that signals the body's cells to absorb glucose from the bloodstream. Type 1 diabetes occurs when the body doesn't make enough insulin, or stops making it altogether. Type 2 diabetes occurs when the body's cells don't respond to insulin. Either way, since sugar can't get into cells, it builds up in the bloodstream. 

Too much sugar in the blood can cause a range of uncomfortable symptoms. These include:

• blurry vision
• intense thirst
• need to urinate often
• fatigue
• numbness or tingling in the hands or feet

Type 1 diabetes often comes on suddenly. It usually strikes children and teenagers, but can appear later in life. It is an autoimmune disease, meaning it happens because the body's immune system mistakenly attacks and destroys the body's insulin-making cells. Type 1 diabetes can't be cured, but it can be managed by taking insulin before eating.

Type 2 diabetes takes longer to develop. It can begin any time from childhood onward. Type 2 diabetes is usually triggered by being overweight or obese and not getting much physical activity. Treatment for type 2 diabetes includes weight loss if needed, daily exercise, a healthy diet, and medications.

Skin Cancer should attack skin and human body

Skin cancer is the most common kind of cancer in the United States. There are different types of this disease. The two most common are basal cell cancer and squamous cell cancer. Melanoma, another type, is less common, but more dangerous. Nearly 70,000 Americans are diagnosed with melanoma each year, and it causes 8,700 deaths. Melanoma is now twice as common as it was two decades ago. The increase is so dramatic that the U.S. Surgeon General has issued a call to action to take steps to prevent melanoma.

One way to protect yourself from skin cancer is by protecting your skin from getting too much of the sun's ultraviolet light. It's especially important to avoid getting sunburned, as this increases the risk of melanoma. Using sunscreen and wearing protective clothing, including a hat with a brim, are good ways to do this.

While sun protection is important for adults, it's even more important for children. Most of the average American's sun exposure happens before age 18. Even a couple of blistering sunburns in childhood increase the risk of later skin cancer.