Thinking about air

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Most people don’t want to think about air. We know it’s there, the medium in which we live and move and have our being. We depend on it with every breath we take. But precisely because of its ubiquity, air is something we take for granted.

Increasingly, though, we can’t do that. Whether our air will be clean enough not to make us sick, whether it will be free of unpleasant odors, whether it will contain low enough CO2 levels to keep the earth from overheating — these are things we find ourselves worrying about.

We’d like air to act as an invisible sponge, soaking up whatever we release into it. But we know that’s unrealistic. Sometimes when we overburden the air’s carrying capacity, we can see or smell the results. But air also contains pollutants that human eyes and noses cannot detect.

For those things we depend on more sensitive measuring devices: machines that sense gases, particulates, oxides and the like. And because most of us lack the equipment to measure such things, we depend on other entities to monitor air quality — government agencies such as the EPA and PCA.

In our more naïve moments, we’d like to imagine that those entities would prevent the knowing discharge of any pollutants at all into the air. But the fact is you can’t burn anything without leaving some residue or creating some byproduct.

So ambient air quality standards have thresholds. They talk about parts per million and include language such as this: “No owner or operator of existing indirect heating equipment shall cause to be discharged into the atmosphere from said equipment any gases which exhibit greater than 20 percent opacity, except for one six-minute period per hour of not more than 60 percent opacity.”

As states go, Minnesota has a pretty good track record of protecting the air. The 2007 legislative session produced bills that increase our commitment to renewable sources of energy and reduce our CO2 emissions. Legislators passed a statewide smoking ban that will greatly reduce citizens’ exposure to secondhand smoke. They appropriated money to study the fuel conversion process at the Rock-Tenn plant, one of the state’s single largest energy users.

Such legislation reflects the obvious fact that air is public property. Even if you own a boiler and smokestack, you don’t own the air into which that stack empties. Even if you own a restaurant, the air your customers breathe wasn’t written into your purchase agreement.

The complicating thing about air quality is that air moves and pollutants disperse. So power plant emissions can’t just be measured at the stack. Readings must also be taken at various distances from the source. Whether you live upwind or downwind from a source of air pollution will greatly influence its effects on you. In extreme conditions, an atmospheric event — a forest fire or a volcano — can affect the air hundreds or thousands of miles away.

Even in normal conditions, the buildup of greenhouse gases in the upper atmosphere is the result of CO2 emissions all over the globe. One area’s efforts to cut such emissions can be offset by another’s indifference.

So part of the challenge in addressing air quality is determining the arena in which the discussion takes place. Should states be allowed to have tougher standards than the federal government? Should the United States sign international agreements if other big polluters refuse to?

Another complication of air quality is that fragrance is in the nose of the smeller. Apart from its health effects, cigar smoke strikes some nonsmokers as foul, but the same person who curses at the first scent of a Havana might welcome an occasional whiff of pipe tobacco.

Even smells that apparently enjoy near universal favor may stir protests from some people. The owner of the BP station at Como and Raymond, who at one time had plans to add a Subway restaurant to a renovated facility on that corner, confronted an unexpected form of resistance. In addition to impassioned discussion about zoning changes, traffic levels, noise and general neighborhood ambience, he was astonished to hear a neighbor voice the fear that an oven at the proposed Subway would emit the smell of freshly baked bread.

And then there are odors that go beyond mere preference. Some people are allergic to the smell of perfume and may suffer asthmatic symptoms in its presence. Should we therefore legislate scent-free workplaces and public buildings?

“What’s in a name?” asked Shakespeare. “That which we call a rose / By any other name would smell as sweet.”

A more vexing question would have been, “What’s in a smell?” And what happens when we don’t agree on its sweetness?