• Combustion of fuels by vehicles produces dangerous fumesexhaust fulmes image by bilderbox from Fotolia.com
  
  The Environmental Health Investigations Branch of the California Environmental Health Tracking Program defines traffic pollutants as contaminants present in air arising from the operations of vehicles and representing a danger to human health. People who are at the most risk for adverse health effects include those who are in contact with heavy amounts of traffic pollutants, such as individuals living in high-traffic areas or those who stay inside cars for long periods of time. People living in areas where 10,000 vehicles or more travel per day may exhibit signs of heart disease, asthma and reproductive irregularities.
  
  

Carbon Monoxide

• Carbon monoxide gas emits no odors and is invisible. Carbon monoxide, with its simple chemical formula of CO, comes from the incomplete burning of fuels. The gas poses a threat to human health since CO acts as a poison, reducing the amount of oxygen available to human tissues. With an insufficient supply of oxygen, humans suffer from nausea, dizziness and a general lack of energy. Individuals subjected to more concentrated levels of carbon monoxide may develop mental confusion, lose coordination, lapse into unconsciousness and ultimately die without medical intervention. The U.S. Product Consumer Safety Commission states that an annual average of 170 people succumbs to CO poisoning which is not due to vehicular emissions.
  
  

Particulate Matter (PM)

• Particulate matter, or PM, consists of tiny particles or liquid droplets ranging in size from 2.5 to 10 microns. These minuscule specks originate from the smoke, fumes and mist of burning fuels and wood. The New Hampshire Department of Environmental Services finds that particulate matter damages materials such as paint and clothing while also affecting human health. PM irritates the throat and nasal passages, adversely affecting respiration and possibly leading to early death. Smaller particles pose risks not only in the immediate vicinity but also traverse borders, creating health hazards in adjoining states and nations.
  
  

Nitrogen Dioxide

• Gasoline- and diesel-guzzling vehicles produce nitrogen dioxide gas. In 1971, the Environmental Protection Agency set a limit for nitrogen dioxide at 53 parts per billion (ppb) averaged every year to protect the public from the harmful effects of exposure to the gas. Nitrogen dioxide may cause reproductive damage in women and abnormalities in fetuses. At high exposure levels, nitrogen dioxide may cause severe respiratory distress leading to death, according to the National Institutes of Health.
  
  

Volatile Organic Compounds (VOCs)

• Burning fossil fuels such as gasoline and diesel in car engines emits volatile organic compounds, or VOCs. Inhaling VOCs over a long period of time harms the liver, kidneys and nervous system, warns the National Institutes of Health. Short-term exposure leads to dizziness, nausea and memory problems. Exposure risks increase during the summer months, when pollutants mix with the heat to form smog. VOCs include substances such as benzene, formaldehyde, toluene and perchloroethylene. In addition to emissions from vehicles, these compounds are present in everyday products such as glue, permanent markers and air fresheners.