Not everyone is aware of it, but Earth Day on April 22 provides workers and unions with a major opportunity to promote occupational health and to forge strategic alliances with environmental organizations.

Of course, not all Earth Day activities promote occupational health, but it’s easy to think of countless ways to make the earth more healthful for workers at the same time as making it more healthful for everyone.

That’s because the distinction between occupational and environmental health is largely artificial. The world is not divided into two realms, with the environment over here and workplaces over there. Workplaces are part of the environment.

Most of the pollution that threatens the environment outside the workplace originates inside the workplace, where the first people who are exposed to it are often workers. Not only are workers the first exposed, they are also often exposed to higher concentrations of pollutants than the rest of the population.

Theatrical smoke is a perfect example: actors and musicians get the heaviest exposure, but enough finds its way into the hall to sicken some of the audience. Too many substances — such as lead, asbestos, formaldehyde and pesticides — harm the health of workers before being released into the broader environment, where they may harm the health of any living thing.

If a toxic material is used in a workplace, it should be controlled so it does not contaminate the workers. If it can be controlled to protect the workers, it must also be possible to control it to protect the rest of the environment. A healthful workplace should also be a non-polluting workplace.

Of course, many employers keep contamination out of the workplace by purposely exporting it through ventilators and smokestacks, so the general population gets the heavier dose. But sending toxins up the stack doesn’t protect workers, because they spend most of their time off the job, where they, too, are part of the general population. Directing pollutants out of the workplace into the rest of the environment only spreads the poison around, often giving workers a double dose, inside the workplace and out.

Really protecting workers from dangerous chemicals and other health threats isn’t accomplished by sending the toxins up a smokestack. The only way to protect them is to completely prevent toxic materials from being released into any part of the environment.

The simplest way to achieve that objective, by far, is to stop using toxic materials in the workplace and stop making products out of toxic materials. Anything that is produced will eventually be incinerated or sent to a landfill or wind up as litter. Even under ideal conditions, any toxic material used in production will eventually contaminate the rest of the environment, because landfills are not eternal. Given enough time, poisons that are used or produced in the workplace will eventually find their way into the broader environment.

So this Earth Day, when we remember that workplaces are part of the environment, we won’t forget the wider benefits of making our workplaces truly healthful, free of toxic materials that can harm the health of workers. Not only is it good for workers, it’s good for the general population and it’s good for the whole environment.

Joel Shufro is the executive director of the New York Committee for Occupational Safety and Health.