Kelley Christensen

Nov 21, 2024 | ehp.niehs.nih.gov | Kelley Christensen

Our planet may be experiencing its sixth known mass extinction event,1,2 with a precipitous loss of insects,3 birds,4 and other species.5 Unseen by our eyes, even Earth’s microbial biodiversity is decreasing.6,7 Yet human immune systems rely on microbial exposures to build up defenses.8,9 In a state-of-the-science review published recently in Environmental Health Perspectives,10 researchers assessed studies on the relationships between the inner and outer layers of microbial...

May 8, 2024 | ehp.niehs.nih.gov | Kelley Christensen

As urban temperatures rise, air pollution concurrently worsens—especially ground-level ozone1 and particulates2,3—because heat alters both atmospheric chemistry cycles and air circulation patterns.4,5 One population that is among the most vulnerable to the twin threats of heat exposure and air pollution is also chronically understudied and plagued by stigma: people experiencing homelessness.

Mar 27, 2024 | ehp.niehs.nih.gov | Kelley Christensen

For many, mention of the Arctic conjures images of polar bears, frigid temperatures, and vast expanses of snow. Yet, as the planet warms—and the Arctic is warming four times faster than the rest of the world1—the permafrost underneath that snow thaws more deeply than in times past. Once-buried waste rises to the surface, and as the ground slumps, infrastructure damage may lead to spills and other releases.