Frequently Asked Questions (FAQs)

Below are some common questions about the PHOENIX air quality monitoring project.

What is PM_2.5 and PM₁₀?

PM_2.5 is the amount, or mass, of particles in the air with a diameter less than 2.5 μm. PM₁₀ refers to particles less than 10μm in size. The EPA regulates PM_2.5 and the current standard is 9 μg in each cubic meter of air (μg/m³) annually averaged.

For short-term exposure, the EPA sets the Air Quality Index (AQI) at 100:

when PM_2.5=35 μg/m³.
when PM₁₀=154 μg/m³.

In Los Angeles during the winter the total AQI reported by the EPA is generally controlled by particulate pollution.

Does your sensor tell us about how toxic the aerosol is?

No, our sensors only tell us how much (mass) is there but not what the particles are made of.

The PM_2.5 is elevated near my home, does that mean it is caused by stirred dust?

Not necessarily. Los Angeles is plagued by poor air quality and PM_2.5 is often elevated across the city. The PM_2.5 in Altadena is often similar to pollution levels in other areas of the city that are far from the fire zone. A goal of this project is to use all the data to separate the particulate that is regional – our ‘normal’ pollution from particulate that likely originates from the burn zone dust and debris.

When do you plan to release maps of dust events?

Now that most of the sensors are in place, we will be turning our focus to doing more analysis aimed at providing the public with a guide to interpreting these data. We hope to have more extensive information on the website within the next couple of weeks.