In Third Rail Repertory Theatre's production of Duncan Macmillan's play Lungs, W (Cristi Miles) and M (Darius Pierce) have an existential crisis about a baby they might have. W is concerned that the mere act of bringing another person into the world is unsustainable. In order to balance the carbon neutrality of the life they've inflicted onto the world, a lifetime of car rides, airplane flights, plastic bag usage and avocado importation, W says, the parents of a newborn baby would need to plant 2,550 trees. "Unless intelligent people stop having babies," she says, "The world is totally fucking fucked."

Of course, you could also say that if intelligent people stop having children the world would eventually run out of intelligent people and also be totally fucking fucked. The question is at the forefront of the play: Should W and M commit to bringing another person into the world? All 90 minutes of run time are spent teasing out the morality and consequences of that action.

W is a Ph.D. candidate in an environmental field, which explains why she has such terrifying statistics and projections about the environment ready at her fingertips (Did you know each person releases 10,000 tons of CO2 into the air in their lifetime, which is the equivalent of 10,000 elephants made of CO2?). The earth contains only so many resources and so much oxygen, and each new person brings us one step closer to maximum capacity. We are reminded of this fact even in the extremely minimalistic set design, which consists of barely enough stage for the actors to move. The backdrop is made of 112 plastic grocery bags hanging on hooks, each with an eerily glowing plastic water bottle.

The environmental issue is at the forefront of the play, but the deeper and more interesting issues lie within its heart. Putting aside overpopulation, does W really want a child? Does she really want a child with M? Fittingly, Cristi Miles imbues W with tremendous complexity in scenes of quiet, traumatic devastation as well as rapid-fire monologues lamenting the state of the planet.
There are no set changes, costume changes, or even lighting or sound changes in director Rebecca Lingafelter's staging of Lungs. There are also no other actors aside from Miles and Pierce. The play takes place over many conversations over the course of several years, with new scenes announcing themselves simply as bits of dialogue that don't fit within the previous scene—such as a chipper "Good morning!" at the conclusion of a scene that takes place at night.

In that way, the play merges many conversations across several years into one long conversation. But the extreme minimalism goes beyond thematic or aesthetic value. In a strange way, it makes Lungs seem more real. It feels like a memory—like one of the characters revisiting their decision years after they came to it.

SEE IT: Lungs is at CoHo Theater, 2257 NW Raleigh St., thirdrailrep.org. 7:30 pm Thursday-Saturday, 2 pm Sunday, through August 26. $25-$45.