Mold

• Mold can be found in the tidiest of homes. It can cause allergic reactions, including severe respiratory problems, in people who are sensitive to it. According to the Alliance for Healthy Homes, more than 1,000 types of mold have been found in U.S. homes.
  
  

Pesticides

• Chemicals used to rid the home of pests can cause a number of maladies, including injury to the nervous and reproductive systems, cancer and birth defects. Immediate symptoms of sensitivity to these chemicals include nausea, dizziness, fatigue and headache.
  
  

Carbon Monoxide

• Hundreds of Americans are killed each year by breathing in toxic carbon monoxide as a result of malfunctioning or improperly used fuel-burning appliances. Proper use and maintenance of these appliances and good ventilation will greatly reduce the risk of carbon monoxide poisoning.
  
  

Combustible Materials

• Combustible materials, such as gasoline, oily rags and papers, can become a fire hazard when left near a flame source, such as a gas water heater. Keep the area around the water heater free from any easily ignited material.
  
  

Poisonous Plants

• Plants are the leading cause of poisoning in children under age 1, according to Parenthood.com. Children should be taught at an early age not to taste anything growing in the yard.