The House yesterday passed legislation designed to give millions of American workers sweeping new protections against occupational diseases.

The legislation, approved by a vote of 225 to 186, sets up procedures under which the government would have to notify workers if they are at risk from hazardous substances in the work place, and requires businesses to pay for monitoring the health of those employes and even the costs of relocating them.

The bill's passage capped a furious lobbying effort that pitted numerous business organizations against an array of groups representing labor, health and some industrial groups -- including chemical companies that supported it after winning changes in the bill.

The Reagan administration has threatened a veto of the measure, a similar version of which is awaiting action on the Senate floor.

Proponents argue that it would make major strides toward preventing the deaths and disabling of hundreds of thousands of workers each year by encouraging early medical intervention against diseases that often are not discovered until decades after workers are exposed to chemicals.

They say the approximate annual cost of about $25 million would be more than offset by reductions in the medical expense of treating occupational diseases -- now estimated at as much as $10 billion a year. "We have the responsibility to workers across this country to let them know about the hazards of the work place," said Rep. Bruce F. Vento (D-Minn.).

But opponents said the measure would create a new layer of bureaucracy, be an expensive burden for business, put U.S. industry at a competitive disadvantage with foreign firms and invite a flood of lawsuits and worker compensation claims.

"This does not respond to the needs of American workers for a safe workplace," said Rep. Richard Armey (R-Tex.). "It responds to the needs of lawyers to live comfortably. It will add a margin of cost that will shut down firms. It is a pound of cure for the AFL-CIO and its declining membership."

Opponents had pushed a weaker alternative that would have toughened current Occupational Safety and Health Administration standards requiring industries themselves to clearly label hazardous materials and train employes in their safe handling. The substitute would have required businesses to notify employes if they have been exposed to harmful substances in concentrations exceeding OSHA standards, forced OSHA to update its existing exposure limits, and mandated a two-year study of the need for a risk-notification program.

The House defeated the substitute Wednesday by a vote of 234 to 191.

The House version would:

Establish a risk assessment board to review medical data and identify groups of workers whose health might be endangered by exposure to hazardous substances.

Require the National Institute for Occupational Safety and Health to notify at-risk workers of the hazard they face, its possible consequences and where workers can obtain medical monitoring and counseling.

Force employers to pay the cost of the periodic medical exams for their at-risk employes unless those workers were exposed while working for a previous employer.

Establish procedures under which exposed workers can be transferred to another job. If no suitable position is available, companies can be required to pay the removed worker's salary and benefits for up to a year.

The House also modified the bill to permit exemptions for firms that can demonstrate they have exceptional health and safety programs and to require employes requesting removal benefits to prove that a disease is about to manifest itself.

Passage of the bill has been a major goal of labor this year, which won the support of some chemical firms and insurance interests. Other business interests, including the National Association of Manufacturers and the National Federation of Indpendent Business, waged an intense campaign to kill it