For a long time they said we didn’t need them, but then something changed and they said that we did: gas masks. This was after 9/11, after the establishment of Homeland Security, when the factory of America’s imagination had achieved its peak production of threats, attacks, conspiracies. I was standing barefoot in the kitchen, listening to the radio turned up loudly, as I liked to do in the morning. The radio! It gives the news a greater impact, and increases the drama of beginning another day in a world I’ve grown used to but know can change at any moment. When the announcement was made, my first instinct was to hold my breath in case whatever it was had already been released into the air. “What?” Victor asked, coming in and turning down the volume. I exhaled. “Gas masks,” I said.

But outside the window, the morning was pale and clear. There appeared to be nothing in the atmosphere beyond the invisible blessing of oxygen. Other things too, equally invisible: a trace of benzene, a low-level reading of mercury or dioxin maybe. But nothing we hadn’t learned to live with. Sometimes at dusk I watch runners on the track around the reservoir, their lungs pumping to take in the maximum cubic feet of air, and the thought occurs to me that maybe they belong to a more evolved subspecies, one actually benefiting from—actually able to break down and harness for energy—elements still toxic to the rest of us. Victor calls it the flagellation parade. He says that they’re wearing away their joints, grinding down cartilage. He says they’ll leave the world limping or crawling on all fours. But to me they seem the image of health: lithe, agile, unharmed by pollution. They know it makes the sunsets more beautiful, all of those particles in the air. The sky turns colors that seem to reflect the peculiar ache of being alive at that hour.

“The threat may not come from common pollutants or shifting winds,” the radio said. “It may not come from airborne pesticides, or a factory fire, or underground tests.” The coffee-maker purred, and Victor took two mugs off the shelf. “Where will the threat come from?” I asked aloud. I felt an intimate connection to the voice, at liberty to ask it questions. “The threat may come from an unknown source,” the radio replied. Even when the news is bad, I am glad to have been answered.

For the time being, the air was still safe to breathe, the radio said. It was all right to go outside, remembering to stop and get a mask at one of the distribution centers being set up in each neighborhood. Victor had been planning on staying in to grade papers, so I offered to pick up masks for both of us on my way back from work.