(Following are excerpts of the speech and slide presentation of Fred W. Bowditch, director of emissions controls for GM, before the M.I.T. joint advisory committee. Some graphs referred to in the speech are reproduced here.)

THERE are at least five major kinds of air pollution. so identified by the regulatory agencies in the state of California and the federal government. These include oxides of nitrogen, sulfur compounds, particulate, hydro-carbons, and carbon monoxide.

The automobile is a contributor of three-these include carbon monoxide, hydrocarbons, and oxides of nitrogen. So, to the degree that any one or all three of these are air pollution problems in a local area, or any urban area, like Boston here, then the automobile is to that degree a significant source of air pollution in that total area.

This of course ranges from being a major problem in the Los Angeles area to being not quite so great a problem in Boston.

Now to understand the problem let' look to where we get these emissions from automobiles. There are basically the four sources indicated here (slide #1). There are evaporative lesses, in the from of hydro-carbon. Of all the, hydrocarbons we get from an automobile, about 20 per cent are evaporative losses. We get that from the fuel tank and the carburetor.

Another 20 per cent of the losses from an uncontrolled car come from the crankcase. And another 60 per cent of those hydro-carbon losses come from the exhaust itself. Now practically all of the carbon-monoxide come from the tail-pipe of the car. And practically all of the oxides of nitrogen-the third pollutant-come from the tailpipe of the car.

What's Being Done?

Now what have we been doing about it? The next slide (slide #2) is an overall view of where we have been. We've been different places between California and nationwide, as you see here. As I indicated initially, California had a major problem so we began in that region.

That is the reason for the two sets of dates. California in 1960 in the first bar-USA same year in the first year because now we are talking about the totally uncontrolled car in our first bar on the left. The bottom part of that bar is the hydro-carbon crankcase emission. The center section of that bar is the exhaust emission losses. That as we said before is about 60 per cent. And the top part of that bar comes from the evaporative losses-about another 20 per cent.

California First

Beginning with 1961 for California cars and 1963 for cars nationwide, a crankcase control system was put on all cars. That took care of about 80 per cent of all crankcase loss. In 1963 in California and 1968 nationwide, we eliminated that remaining crankcase loss.

In that same year, nationwide and in 1966 in California the first exhaust control system was put on the cars and that brought us down to about a 50 per cent reduction from where we started from.

The last bar is the 1970 California model and the 1971 nationwide model and that shows a little over 100 gramsof automobile pollution per car per day.

Now you get a slide rule, make a division and there you have an 80 per cent reduction in those hydro-carbon losses.

These numbers are not from prototype engineering cars. Those numbers are from cars now in the hands of the public. We borrow them, run tests on them, and give them back to the public.

There are cars with higher emissions than that and there are also cars with much lower emissions than that. Those numbers cited are the average emissions from cars in the hands of the public.

Carbon Monoxide

So that's what we've done thus far in controlling hydro-carbon losses. Now the second source of emission that we've been working on is the carbon monoxide (slide =3). And with this, we've made a reduction of about 65 per cent. Now what's even more important, of course, Is what has all this done for our atmosphere. In this instance, we make estimates of what we think is done in the atmosphere.