The East Valley was hit with hazardous air quality levels early Monday morning, with residents encouraged to stay inside.

A High Pollution Advisory is in effect due to lingering dust, pollen and smoke across parts of the Valley. Expect hot ...

After years of failing to meet Clean Air Act standards, metro Phoenix won its argument that nonlocal ozone shouldn't count.

The best rain chances on March 29 were south of the Phoenix area, including southern Maricopa County and Pinal County.

Federal regulators ruled Monday that pollution from Mexico , not local sources, is why Phoenix fails air quality standards.

The EPA won't impose stricter air rules on Phoenix, citing international pollution as the cause for failing ozone standards.

The EPA's air quality assessment will allow businesses to avoid costly environmental-focused regulatory requirements after ...

The EPA's decision on the Valley's ozone nonattainment issue could have big impacts on public health and the local economy. Here's what to know.

The EPA is considering delaying a decision that would classify metro Phoenix's ozone problem as "serious" and potentially bring serious economic consequences. Local officials say they are working to ...