context: If you're like most folks, when you hear that someone has lung cancer, you probably assume he's a smoker. But there's more to it than that. The truth is you can get the disease even if you've never put a cigarette to your lips. There are lots of reasons why this can happen, but if you can help cut down your risk. First, pay attention to some of the things that bring on lung cancer when you don't have the tobacco habit. Secondhand smoke. There are two types: the stuff a smoker breathes out and the cloud that drifts from a cigarette, pipe, or cigar. Both are bad for you. So even if you wouldn't dream of lighting up a cigarette, you still take in harmful chemicals when you're around someone who does. There are at least 70 kinds in secondhand smoke that can lead to cancer. There are no safe amounts, so try to avoid secondhand smoke as much as you can. Take a pledge to make your home and car tobacco-free zones. Radon. It's a gas that naturally forms from soil and rock. You can't see, smell, or taste it. Low levels of the stuff are a natural part of the air outdoors, but it's more likely to be a problem inside homes and buildings. It can creep in from the ground through cracks in the floors or walls. If you breathe in radon over long periods of time, you may end up with lung cancer. That's because it breaks down into tiny particles that can get into your lungs and damage cells there. The gas is the second most common cause of the disease besides smoking. You can check how much of it is in your home with a detection kit, or you can hire a professional to do it. If the levels are too high, it's a good idea to work with a contractor who has experience with this issue. He may seal cracks in your floors and walls and use other techniques to help lower the amount of the gas in your home. Asbestos. It's a group of minerals that was used in a lot of building supplies and products until researchers found it was harmful. When you breathe it in, the fibers get stuck deep in your lungs and over time may lead to lung cancer. The more you're in contact with asbestos, the higher your risk. It sometimes lurks in older homes in places like steam pipes or tiles. It's not a hazard unless the material gets damaged and releases fibers. Hire a trained professional if you need to repair or remove it. Genes. Sometimes changes to the DNA of your lung cells, known as "mutations," can lead to cancer. There are several ways this can happen. For example, you may be born with problems in chromosome number 6 that make you more likely to get lung cancer. Or you may naturally have less of an ability to clear away chemicals from your body that can cause the disease. Another possibility: Your body may be unable to repair damaged DNA, which puts you at higher risk when you come into contact with chemicals that can cause lung cancer. There aren't any tests to check if you have any of these genetic problems. Your best bet is to avoid things that are known to increase your odds of getting the disease. Air pollution. In the U. S. dust, smoke, and chemicals in the air cause about 1%-2% of lung cancers. Researchers suspect that polluted air can cause changes in your DNA that may set the stage for a higher risk of the disease. The more air pollution you breathe in, the greater your chances of getting this type of cancer. Diet. What you put on your plate could affect the health of your lungs. A new study looked at how the glycemic index, which measures how quickly a carbohydrate raises your blood sugar, may be linked with lung cancer risk. Researchers in one study found that people who ate a diet with the highest glycemic index had a higher risk of getting the disease. Foods that may be troublesome are white bread, sugary cereal, white rice, pretzels, and popcorn. Healthier choices are whole-wheat bread, oatmeal, sweet potatoes, lentils, and most fruits. Experts aren't exactly sure why a high-glycemic diet may be connected with lung cancer. One possible reason is that it raises your blood sugar, which increases levels of proteins called insulin-like growth factors. Earlier studies suggest they may play a role in the development of the disease.