Assessment of the Contribution of Wildfires to Ozone Concentrations in the Central US-Mexico Border Region

Abstract

The annual trends and spatiotemporal patterns of monthly 8-hour maximum ozone (8-hr max O 3 ) concentrations in the Paso del Norte region were analyzed, and their associations with fires were examined for the 2001-2010 period. Hourly O 3 measurements were retrieved from the Environmental Protection Agency (EPA) Air Quality System, while the times and locations of fires were acquired from the MODIS fire detection module. The absolute 8-hr max O 3 concentrations were comparable in urban, rural and background sites. Time series analysis of deseasonalized monthly 8-hr max O 3 levels showed statistically significant declining trends for most of the sites located in populated areas, and high correlation coefficients among these. Conversely, a 0.12 ppbv/yr increase of 8-hr max O 3 concentration was computed for Chiricahua, a background site located in a Class I protected area. Strong relationships between the monthly 8-hr max O 3 concentrations and categorical variables representing the number of fire detections for each month in six buffer zones were computed. Fire incidents near the sites (within 400 km) in central Arizona, central Texas and western Mexico triggered a decrease in the 8-hr max O 3 concentration by 1 to 12 ppbv in urban and rural sites, and an increase of 3 ppbv in Chiricahua. Conversely, fire incidents in southeast US, Cuba and central Mexico contributed from 5 up to 19 ppbv. These findings indicated that regional fire incidents may trigger high O 3 episodes, which may exceed air quality standards.

Characterization of water-soluble organic matter in urban aerosol by 1H-NMR spectroscopy

“…We previously determined that biomass burning contributed 3.0 μg/m 3 to PM 2.5 ; however, the profiles of the remaining factors also contained elemental and organic carbon (Chalbot et al, 2013a,b,c,d). The outcomes of the PMF analysis were re-processed by regressing the factor contributions to organic carbon (OC) and elemental carbon (EC) levels to estimate the influence of biomass burning on PM 2.5 OC and EC.…”

A review of atmospheric chemistry observations at mountain sites

“…At HPO and MBO, which are both strongly influenced by springtime outflow from East Asia, the O 3 levels showed larger increases at higher percentile levels than those at lower percentile levels (Gratz et al 2015;Tanimoto 2009). A statistically significant positive trend in the mean maximum daily 8-h average (MDA8) O 3 concentration at 0.12 ppb year −1 was observed at CHA for the period from 1989 to 2010 (Chalbot et al 2013). The surface O 3 recorded at MLO in the Northern Pacific has shown a significant increase of 0.16 ± 0.04 ppb decade −1 (Oltmans et al 2013).…”

“…Jaffe et al (2008) showed that the area of summer burning in the western USA was significantly correlated with daytime summer O 3 concentrations at LAV and YEL, which indicates that the presence of fire played an important role in increasing the summer O 3 in the western USA. Chalbot et al (2013) indicated that regional fire incidents might trigger high O 3 episodes. They estimated a 3 ppb increase in the MDA8 O 3 concentration at CHA in Arizona by such incidents within 400 km of the sites.…”

Effect of Nearby Forest Fires on Ground Level Ozone Concentrations in Santiago, Chile

“…These plumes can also affect nearby cities leading to ground level concentrations that largely surpass air quality standards [8,10,11]. Nevertheless, there are few evaluations regarding ozone behavior in large cities exposed to polluted masses transported from nearby forest fires [3,8,11,12] Results range from moderate decreases at Arizona and Central Texas, US, and western Mexico, when the cities are located less than 400 km from fire [12], to large increases as in the city of Edmonton, Canada, when the city is located 300 km from the fire [11]. On the other hand, measurements in Mexico City (MCMA) did not demonstrate significant differences in ground level ozone concentrations in periods with active fires [13].…”