Stay-at-home orders issued by local and state governments this spring have led to more people working and taking classes from home, which means fewer cars on the road. They also spurred business closures or slowdowns that likely reduced industrial emissions. But how much was our local air quality affected since the shutdown began?
To answer that question, GASP examined daily average PM2.5 concentrations at the Liberty, Parkway East, and Avalon monitor sites and then compared those numbers to the average concentrations over the past three years. We used that comparison to account for the fact that particulate matter pollution tends to improve as winter turns to spring.
This is what we found: Since the orders first took effect in mid-March, PM2.5 concentrations are about 23 percent lower than the area might expect at the Liberty monitor, and concentrations at the Parkway East air quality monitor are about 13 percent lower than expected.
But GASP also found the improvements are not universal. Our math showed that PM2.5 concentrations at Avalon are almost entirely unchanged when adjusted for the usual seasonal improvement.
In addition, hydrogen sulfide exceeded the 24-hour state standard twice earlier in May. This should serve as a reminder that even ‘improved’ air still leaves a lot left to be desired on the road to clean air.
We hope the data can help shed some light on ways to improve air quality as the economy reopens.
One actual bit of good news our research showed was that before this novel coronavirus came to town, Allegheny County air quality was trending toward an improvement in 2020. Specifically, at all the monitor data we looked at, PM2.5 levels from Jan. 1 through March 15 were – on average – lower than they had been the past three years.
“While there have been modest improvements to air quality recently, regulators should not take their eye off the ball,” GASP Executive Director Rachel Filippini said. “ACHD committed earlier this year to promulgating new coke oven regulations and to coming up with a plan to impose corrective action requirements on industry during short-term pollution events.”
She added: “As the economy reopens and as industry ramps up production, ACHD needs to be prepared and not caught flat-footed like they were during the last significant air inversion event.”
For those who would like to take a deeper dive into the data, check out these graphs:
