The idea of a green jobs-centric economic growth strategy is hardly new, having been touted by progressives for over a decade now. But progressives have done a poor job explaining how exactly green investments fuel economic growth. Instead, the issue has been weighed down by debates over the definition of a green job and exactly how many jobs a certain green policy creates. These are important questions, but fixating on them obscures the broader case: Green investments create a stronger economy by promoting health and opportunity, particularly for low- and middle-income workers.

The middle-out growth model rests on the notion that economic growth doesn’t come from the rich. To be sure, the economy needs people to run companies and allocate financial capital, and these jobs tend to pay quite well. But growth comes from the vast majority actually working in the economy, not the ones running it from above.

Unfortunately, rhetoric promoting green investments tends to glide past the broader middle-out narrative in favor of emphasizing the growth potential of the green industries themselves. The fact is that investments in green industries are a vital component of a middle-class focused economic growth strategy. The industries most often characterized as green are renewable energy and energy efficiency (such as home weatherization), but data from the Bureau of Labor Statistics (BLS) show that industries such as public transportation, water treatment, and waste services are also highly green and exhibit significant growth potential. And jobs in these industries push against the trend of ever-rising employer demand for higher education. Evidence shows that the greener the industry, the greater its share of jobs that don’t require a college degree. For instance, the school bus transportation industry is considered heavily green, and more than 85 percent of its workers (mostly school bus drivers) lack a four-year college degree. This is important for the roughly 70 percent of the workforce that lacks one.

Furthermore, green investments promote middle-out growth by revitalizing the manufacturing sector. The green economy is roughly twice as manufacturing intensive as the overall economy, with key industries that include the manufacture of energy-efficient household appliances and heating, ventilation, and air conditioning systems. Whether directly or indirectly, green investments help manufacturing regain its importance in the economy.

Luckily, green industries are already oriented toward growth. Over the last ten years, green industries have grown faster than nongreen industries, and BLS projections suggest that they will continue to outpace the rest of the economy over the next ten. This is true even within the manufacturing sector, where green manufacturing industries are growing over a third faster than nongreen manufacturing industries.

It’s not surprising that green industries outperform their nongreen counterparts. Many green industries are relatively new compared to the more mature, dirtier industries, so there’s more room for growth—and the climate evidence certainly suggests that the need (and thus demand) for green technologies will be strong for decades to come.

But there is another case for green investments that should be made beyond simply highlighting green industries: The current “dirty economy” model inherently favors the rich at the expense of the lower and middle classes, and this in turn hampers middle-out growth. This outdated economic model relies on allowing businesses to pollute, causing disproportionate harm to the low- and middle-income workers that the economy depends on for its growth.

There are a few reasons why pollution disproportionately affects low- and middle-class workers. Cheaper housing, such as those near highways and refineries, tends to have greater exposure to environmental pollutants. Studies of metropolitan areas and pollution data have found a strongly negative relationship between income and pollution exposure. This relationship persists even within specific cities: A University of Massachusetts study looked at communities and the pollution distribution within cities, and found that a $10,000 increase in a community’s median income is associated with a 7 percentage point decrease in the probability of being in the more polluted half of the city. In other words, the lower the community’s income, the more likely it will be exposed to pollution.

Moreover, EPA researchers find that the most polluted locations have higher-than-average concentrations of African Americans, Latinos, and Asian Americans. Low- and middle-income people also tend to be in older housing and attend schools in poor condition, and are thus more likely to be exposed to indoor pollutants.

Persons in low-income households can also be more sensitive to pollution, meaning that the same level of pollution actually causes them more harm than higher-income persons. This is driven in part by having less access to health care and, for African Americans in particular, higher incidence of diseases like diabetes that can interact with pollution-induced afflictions such as asthma.

Why does this all matter? Pollution can severely dampen the ability of middle-class workers to be productive, to innovate, and to reach their economic potential. For example, lead pollution, which can come from both leaded-gasoline emissions and lead paint in older buildings, can lower intelligence, increase violent behavior, and is even associated with higher incidence of ADHD. For middle-out economic growth to occur, we’ll need productive, innovative workers. A cleaner environment is essential to building such a workforce.

The power of this message is enhanced as the policies get more specific. For example, investing in the weatherization of homes, especially for low-income families, would reduce pollution and boost these households’ discretionary income—both effects promoting middle-out growth. And returning to the example about lead pollution, cleaning up the lead in old houses and the surprisingly high concentrations still in the soil (especially in urban areas) would enhance productivity and reduce crime, easily paying for itself; Kevin Drum at Mother Jones estimates the benefit would be a whopping ten times the initial cost.

Green investments can be justified solely through their creation of green jobs and the development of green industries. To be sure, the above examples, like most green investments, would create tens of thousands of jobs in the short-run. But such messaging is highly sensitive to economic conditions. Green investments sold to the public this way can be more easily dismissed if jobs don’t appear to follow immediately—if, say, the effect gets swamped by larger macroeconomic trends or if the projects take time to get off the ground. This helps explain why public support for green investments has waned over the last few years.

Instead, the case must be made that green investments provide broad—and permanent—economic benefits by moving us toward a more sustainable economic model, one that promotes a healthier, more productive, and stronger middle-class and greater economic mobility for all. It may seem more difficult to make this argument, but bundled as part of a broader middle-out agenda, it may prove the more resilient and persuasive case for a clean economy.