Seventy-four days – and counting – without good air quality in Sacramento region

Smoke hovers over Northern California on Saturday, September 2 in this image from NASA.
Smoke hovers over Northern California on Saturday, September 2 in this image from NASA. NASA

It’s been hazy for months in Sacramento.

Regulators typically deem air quality “good” across the entire region at least 100 days a year. Even during the summer, when pollution is typically at its worst in Sacramento, spurts of bad air are reliably alleviated by good days.

But not since June 26 have regulators declared air quality good throughout the entire region, according to data from Sacramento Region Spare the Air.

During July and through much of August, the problem was ozone pollution, which is typically caused by motor vehicle and industrial emissions. Lately, smoke has been the primary culprit for air pollution.

The last time the region went this many days without at least a single day of “good” air quality was July 2 to Oct. 3, 2012.

The Environmental Protection Agency classifies air quality into six categories: good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous. The categories correspond to an Air Quality Index that runs from 0 to 500. When the index is between 0 and 50, air quality is considered good.

Special districts track air quality at multiple points throughout the region. Every day, they publish the maximum air quality index for the Sacramento area – the worst reading of the day across all tracking points. At some place in the region for the last 74 days, that index has been above 50.

Already, the region has seen 17 Spare the Air days in 2017, tied with 2016 for the most Spare the Air days in 15 years.

Since June 26, regulators have classified 38 days as moderate air quality; 35 days as unhealthy for sensitive groups and one day as unhealthy.

The official forecast through at least Tuesday: air quality that is moderate to unhealthy for sensitive groups.

Phillip Reese is The Bee’s data specialist and teaches at Sacramento State. Reach him at 916-321-1137 or 916-278-5420.