Scientific research has shown that housing-related hazards pose a broad spectrum of risks to human health. Housing conditions can play a significant role in respiratory health and greatly increase and intensify susceptibility to asthma, allergies, and other respiratory illnesses. Substances found in the home, such as radon and asbestos, can increase the risk of cancer, which is the second leading cause of death among adults and children in the US. Lead poisoning causes reduced IQ and attention span, hyperactivity, impaired growth, reading and learning disabilities, hearing loss, insomnia, and a range of other health, intellectual, and behavioral problems. Carbon monoxide poisoning results in more than 200 accidental deaths a year and, at much lower levels, causes flu-like symptoms, which often go undiagnosed.