Car care and health care: what's the connection? Ask anyone whose bald tires lead landed him in the emergency room. Ask an asthmatic who becomes ill from thick air pollution in rush hour traffic.

The latter is a serious issue with environmentalists as well as automotive designers. 1994 model cars produce a fraction of the harmful emissions that their 1984 predecessors did.

Still, nearly two thirds of the total carbon monoxide, more than a quarter of the hydrocarbons and a third of the nitrogen oxides which pollute our atmosphere come from motor vehicles. These percentages decrease dramatically as the vehicle population, with enhanced emission control systems, gets younger. As we improve maintenance of existing vehicles we significantly reduce harmful exhaust.

Periodic engine checkups, along with necessary maintenance, can make a big difference in exhaust emissions. Even the simple replacement of a dirty air filter, one of the most common offenders, can reduce emissions and save gas.

A few more things motorists should know about vehicle condition:

If smoke is coming out of the exhaust, it may mean:

• The fuel system is malfunctioning.
• The engine control computer system is malfunctioning.
• The engine may need major work due to worn piston rings or valves.

If an exhaust analyzer shows high carbon monoxide content, it may mean:

• The air filter is dirty.
• The PCV (positive crankcase ventilation) system is clogged.
• The cold start system is malfunctioning.
• The fuel system is operating too rich.
• The ignition timing is incorrectly adjusted.
• The thermostatic air control is malfunctioning.
• The air injection system is malfunctioning.

If an exhaust analyzer show high hydrocarbon content it may mean:

• Fouled spark plugs.
• Faulty spark plug wires.
• Faulty ignition cap or rotor.
• Incorrect ignition timing
• The fuel system is too rich.
• There's a vacuum leak.

For most cars, with their numerous sensors, computers and other electronic circuitry, accurate diagnosis is a "must". In the long run this procedure, along with needed service, can save time, fuel and, of course, our environment.