Ozone

When wildfire smoke is in the air, doctors urge people to stay indoors to avoid breathing in harmful particles and gases. But what happens to trees and other plants that can’t escape from the smoke? They respond a bit like us, it turns out: Some trees essentially shut their windows and doors and hold their breath. As atmospheric and chemical scientists, we study the air quality and ecological effects of wildfire smoke and other pollutants. In a study that started quite by accident when smoke overwhelmed our research site in Colorado, we were able to watch in real time how the leaves of living pine trees responded. How plants breathe Plants have pores on the surface of their leaves called stomata. These pores are much like our mouths, except that while we inhale oxygen and exhale carbon dioxide, plants inhale carbon dioxide and exhale oxygen. A highly magnified view of stomata in a maize leaf. Umberto Salvagnin/Fli...

Did you receive a mail-order package this week? Carriers in the U.S. shipped 64 packages for every American in 2022, so it’s quite possible. That commerce reflects the expansion of large-scale retail in recent decades, especially big-box chains like Walmart, Target, Best Buy and Home Depot that sell goods both in stores and online. This has led to the growth of distribution centers that fulfill these orders. While mail-order commerce is convenient, these centers also have harmful impacts, including traffic congestion and air and water pollution. I study environmental history, and I am part of a group of scholars examining the environmental impacts of big-box stores like Walmart, Target, REI and Bass Pro Shops. Sustainability is a hot topic in the retail sector, but my research on the history of Target – the sixth-largest retailer in the U.S. – shows how retail companies have largely escaped the kinds of environmental regulations that affect other sectors such...

As the eastern U.S. and Canada reeled from days of thick wildfire smoke in early June 2023, millions of people faced the reality of climate change for the first time. Shocking images of New York under apocalyptic orange skies left many people glued to air quality indices and wondering whether it was safe to go outside. What they might not realize is that the air many of them breathe isn’t healthy even when wildfire smoke isn’t filling the sky. In fact, the air that 99% of the world’s population breathes is not safe, according to the World Health Organization. Air pollution is everywhere, in cities and in the countryside, visible and invisible. It kills an estimated 7 million to 10 million people a year, taking 2.2 years off global average life expectancy. Worldwide, that’s a combined 17 billion life years. There is growing evidence that even low levels of air pollutants damage the human body, increasing the risk of cardiovascular and respiratory illness...