SACRAMENTO - Just weeks after the Air Resources Board (ARB), California's anti-smog agency, ordered car makers to produce the world's lowest polluting cars, it is considering standards for much smaller utility engines, ranging from those used in leaf blowers and chainsaws to small utility generators and lawn mowers.

Many of these engines individually emit up to 50 times more pollution per horsepower than a typical truck engine. A chainsaw, for instance, typically operated for two hours, emits as much smog-forming hydrocarbons as a new car driven 3,000 miles, according to ARB staff estimates, while a lawn mower running for 30 minutes will match a car's hydrocarbon output over 172 miles. Combined, the pollution from all small engines operating in the state is equal to the hydrocarbon from 3.5 million 1991 model cars, each driven 16,000 miles a year.

The ARB will consider the standards during a hearing Friday, December 14, in San Francisco at the Bay Area Air Quality Management District, 939 Ellis Street, beginning at 8:30 a.m.

The ARB staff has proposed two sets of standards, one of which will cut emissions of smog-forming hydrocarbons and carbon monoxide by 46 percent by the year 1994 and another that will reduce emissions 55 percent by the year 1999. In all, the proposed standards are expected to reduce emissions by about 433 tons per day, statewide, by the year 2010.

The standards will cover two types of engines. They include two-smoke models such as those used in chainsaws and leaf blowers, as well as more sophisticated four stroke engines, similar to those used in cars, which are used in equipment such as riding mowers and small generators.

The ARB is not proposing a ban on any type of equipment or engines and expects all types currently being produced to continue being available,

Two-stroke engines, such as those used on hand-held equipment, have very high emissions because they mix lubricating oil with gasoline and because of their very rich air/fuel mixtures. Manufacturers are expected to meet the proposed standards by improving the fuel-efficiency of their engines by using better carburetor systems. At least one engine that currently meets the proposed standards consumes 25 percent less gasoline than other models.

Manufacturers of both two and four-stroke engines are also expected to improve engine operations by more use of overhead valve designs, similar to those on cars, to improve the burning of fuel.

To meet the proposed 1999 standards, some makers of four-stroke models may rely on catalytic converters, similar to those used on some motorcycles engines as early as 1984. Some chain saws sold in Europe also have been equipped with catalytic converters since 1989.

ARB staff has estimated the cost of future controls to average about $30 per engine.
In addition to their clean air benefit, the standards are being proposed to satisfy a court order in the San Francisco Bay Area. Earlier this year, the Federal District Court ordered the ARB to adopt rules governing these engines by January, 1991, to carry out commitments made by local air quality officials in a clean air plan for the area.

Last September, the ARB adopted standards that will cut emissions from cars and trucks by an additional 85 percent by the year 2003 and will force the use of alternative fuels. The new standards also required production of up to 40,000 electric cars by 1998 and 200,000 a year by 2003.

The proposal governing these smaller engines is just as important to future clean air gains, according to the ARB staff. "All pollution sources, both big and small, must do their share if we are ever able to offer all Californians air that is healthy to breathe," noted James D. Boyd, ARB executive officer. "We've been regulating some major pollution sources, such as motor vehicles and oil facilities for over 20 years and these small utility engines have much higher emissions for their size simply because they have been unregulated up to this point.

"We are simply asking these manufacturers to take the first step in controlling their pollution just like car manufacturers and others did years ago."