Why it’s so confusing to determine air quality in Los Angeles right now

on AirNow fire card includes data from PurpleAir sensors (that’s what the little circles represent) and Watch Duty, a non-profit fire tracking appalso shows PurpleAir data. But possibly due to different calculations and processing delays, the air quality index reported by the same sensors can vary significantly from map to map. For what’s known as PM2.5 pollution, or tiny respirable particles of smoke and dust, a PurpleAir sensor located south of Los Angeles International Airport simultaneously returned an air quality index of 28 Monday on the AirNow website. 20 on WatchDuty and 5 on PurpleAir official page.

Each of these values ​​generally indicates healthy air, but things can get more complicated when other types of data are added to the calculations. That’s exactly what companies like BreezoMeter and Ambee are doing, hoping to provide what they describe as accurate “hyperlocal” estimates over many miles between some sensor locations.

BreezoMeter was founded in Israel and has raised tens of millions of dollars in venture capital funding before Google acquires it in 2022. for more than $200 million, according to Israeli media. (Google declined to comment on the value of the deal.) It powers the air quality data seen in the Weather app on Apple devices and the Google Maps app. Meanwhile, Indian startup Ambee is responsible for the air quality data in the WeatherBug app, which is among the most popular weather apps in the world.

Yael Maguire, vice president of geosustainability at Google, tells BreezoMeter assesses air quality on an hourly basis across a wide range of pollutants and locations, generating more data than many government systems. To make its calculations, the company uses information collected not only from EPA and PurpleAir sensors, but also from satellites and other sources, such as weather and traffic reports. Similar data is included in Ambee’s own algorithm, according to its CEO Jaideep Singh Bachher. “We want to give people the right data when and where they need it,” he says.

Volkens says he doesn’t trust those systems. The inexpensive PurpleAir sensors they use in part are not suited to the conditions they are often deployed in the U.S., including during wildfires, he says. But he admits that while they tend to be off on the raw numbers, these sensors can be accurate about 90 percent of the time in determining the recommended level — that green-to-maroon scale that’s often enough for people to take decisions about how to protect their health.

Andrew White, a representative of PurpleAir, says that its sensors are found to be accurate and that it does not control how other services perform calculations using its data. Google’s Maguire says the company “provides industry-leading, highly accurate air quality information,” including “even in areas with limited monitoring.”

Jennifer Richmond-Bryant, an associate professor of forestry and environmental resources at North Carolina State University who has studied PurpleAir sensors, says the safest bet for anyone concerned about air quality is to trust the most the high number or color level among different services. “I have more faith in AirNow’s numbers because I understand them,” she says. But “it can never hurt to be overly conservative when it comes to protecting yourself.”