It's best to have a leaking gas valve repaired by a professional in order to be safe, according to DoItYourself.com. This may seem like an expensive solution, but once it has been determined that there is in fact a gas leak, calling in a technician is the safest option.
A homeowner runs the risk of inhaling toxic fumes if they are exposed to leaking gas that isn't remedied in a timely manner, notes DoItYourself.com. Regular maintenance is important; anything in a household that uses gas should be regularly inspected and checked for leaks often. One way to check for leaks in gas lines or valves is to put some soap and water in a spray bottle and spray the mixture onto the gas lines when the appliance is on. If the soap and water starts to bubble on any part of a valve or gas line, that's an indication of a leak. In this case, it is best to seek the help of a professional. Even if they don't make a service call, it's worth it to at least talk to one on the phone and get advice.
Carbon Monoxide is a gas that can leak but go undetected. The way to keep track of any possible carbon monoxide leaks is to always have a home's carbon monoxide detector tested and supplied with fresh batteries.