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Investigating Degraded Air Quality Despite A Lack of Smoke

Though most time spent as an Air Resource Advisor is spent working with the impacts of the fire, this isn’t always the case. At the end of May, the West Mims Fire was producing little smoke, but air quality was mysteriously degrading. All sites in the area were showing moderate air quality, with several showing brief periods of worse conditions on May 30, 2017.


The worse air quality did not match the smoke produced by the fire, and though there were some other fires in the area that could contribute, they likely still weren’t enough to produce such a noticeable region-wide response. Indeed the monitors nearest West Mims ironically showed some of the lowest PM 2.5 values in the area. MODIS satellite imagery confirmed an increase in particulates with a higher aerosol optical depth on May 30:


Though high clouds (or perhaps even the obscuring haze itself triggering the cloud flag) masked much of the area, it’s apparent the values were relatively high, especially compared to what was observed over the area a few days earlier:


Ultimately, after some discussions with a National Weather Service meteorologist and an environmental consultant with the Florida Department of Environmental Protection, the most likely culprit was an outbreak of Saharan dust. A US Navy model also analyzed the presence of dust in the region:


Though the 30th showed the poorest conditions associated with the dust, it took several days for regional PM 2.5 levels to return to more typical values.

Community Concerns about Air Toxics – Using environmental biomonitors

Plants can also be exposed to air contaminants and can store these chemicals in their roots, stems, or leaves. These plants can be used as environmental biomonitors to understand levels of chemicals in our environment.

Pinal fire possible helispot

Here in Globe, there is a community concern about exposure to dioxin from the Pinal Fire. This concern stems from past herbicide application in 2,500 acres of brush at the base of the Pinal Mountains. Although the herbicides were not detected in previous environmental samples, there were concentrations of dioxins detected in the soil of the helicopter landing pads (helispots) where the herbicides were mixed.

Group photo of collection Guys collecting biomass

Dioxins bind to soil and do not easily separate into the air. However, roots that run through contaminated soils could release dioxin into the air if those plants are burned. For this reason, we collected biomass samples of brush at two locations near the Pinal Fire – (1) a site that based on historical environmental sampling and local information may be the site of an herbicide mixing helispot and (2) a location near the fire that was not treated with the herbicide (a control site).

USFS is currently working with the US EPA and academic researchers to determine the best analytical method to measure for dioxin in the collected brush samples.

Photos of crew collecting biomass samples to be analyzed for dioxin concentrations

Community Concerns about Air Toxics – Using Specialized Air Monitors 


Evaluating smoke exposure generally involves measuring the air for PM2.5 as a main concern for public health. However, if we want to know what specific chemicals are in the air we need to utilize specialized air sampling equipment. Here in Globe, there is a community concern about exposure to dioxin from the Pinal Fire. The Arizona Department of Environmental Quality contracted Ramboll-Environ to conduct a 2-day air sampling campaign in Globe to measure for dioxins.

Air samples were collected using established sampling methods from the US EPA. This method utilizes the Tisch Environmental Poly-Urethane Foam (PUF) high volume air sampling system (pictured below). These high volume samplers use a vacuum blower motor to draw large amount of air across a combination filter and glass sampler (125-250 liters per minute). For this sampling campaign, two sets of 24-hr PUF samples were collected at each location – Globe Ranger Station and Globe Courthouse on Sunday May 28th through Tuesday May 30th. Collected samples will be sent to Vista Analytical Laboratory for a rush analysis completed by Monday June 5th.

Dioxin 1  Dioxin 3

The measured air concentrations can be used to calculate health risk levels to be compared to established risk levels. Additionally, these concentrations can be compared to other communities where dioxin exposure is common to understand if these measurements are elevated. Dioxins bind to soil and do not easily separate into the air. They are not expected to be found at significant levels in the ambient air or smoke.














The sampling and subsequent laboratory analysis is conducted using US Environmental Protection Agency (EPA) Compendium Method TO-9A




Meet the E-Sampler Nephelometer


Meet the Met One E-Sampler portable Nephelometer

Short-term exposure to particulate matter (PM) is the principal public health concern from exposure to wildfire smoke. Airborne smoke particulates, especially particulates smaller than 2.5 micrometers (µm) in diameter (PM2.5), pose potential safety and health consequences that can negatively affect the nearby communities. Deployment of air monitors during wildland fires is important to identify the impact, assess the public’s level of risk, and to determine adverse health effects to the local communities. Through the use of the E-Sampler we are able to display particulate concentration levels in affected areas, then we can use that data so that we can broadcast health advisories, and promote recommendations to decrease public exposure.

The E-Sampler system offers real-time data reporting capability and links to the EPA’s AirNow website to provide air quality information.

The E-Sampler is a type of nephelometer (an instrument for measuring concentration of suspended particulates) automatically measures and records real-time airborne PM10, PM2.5, or TSP particulate concentration levels using the principle of forward laser light scatter. In addition, the E-Sampler has a built-in 47 mm filter sampler which can optionally be used to collect the particulate for subsequent gravimetric mass or laboratory evaluation. The E-Sampler combines the excellent real-time response of a nephelometer with the accuracy and traceability of a low flow manual gravimetric sampler.

Laser Light Scatter System

Sample air is drawn into the E-Sampler and through the laser optical module, where the particulate in the sample air stream scatters the laser light through reflective and refractive properties. This scattered light is collected onto a photodiode detector at a near-forward angle, and the resulting electronic signal is processed to determine a continuous, real-time measurement of airborne particulate mass concentrations.

The AirNow Web site provides the public with easy access to national air quality information and offers daily Air Quality Index (AQI) forecasts as well as real-time AQI conditions for over 300 cities across the US, and also provides links to more detailed State and local air quality Web sites.

Wildland Fire Air Quality Response Program:

AIRNOW website: