Abstract
The annual trends and spatiotemporal patterns of monthly 8-hour maximum ozone (8-hr max O3) concentrations in the Paso del Norte region were analyzed, and their associations with fires were examined for the 2001–2010 period. Hourly O3 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 O3 concentrations were comparable in urban, rural and background sites. Time series analysis of deseasonalized monthly 8-hr max O3 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 O3 concentration was computed for Chiricahua, a background site located in a Class I protected area. Strong relationships between the monthly 8-hr max O3 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 O3 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 O3 episodes, which may exceed air quality standards.
Highlights
The World Health Organization (WHO), the US Environmental Protection Agency (EPA) and the European Commission enacted the air quality threshold values for atmospheric O3 to protect human health
O3 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
A 0.12 ppbv/yr increase of 8-hr max O3 concentration was computed for Chiricahua, a background site located in a Class I protected area
Summary
The World Health Organization (WHO), the US EPA and the European Commission enacted the air quality threshold values for atmospheric O3 to protect human health. In the US, the latest National Ambient Air Quality Standards (NAAQS) revision in 2008 requires that the three-year average of the annual fourth-highest daily 8-hour maximum (8-hr max) average at every ozone monitor is less than or equal to 75 ppbv (from 80 ppbv enacted in 1997) (US EPA, 2008). Non-attainment areas (exceeding the O3 standard) include metropolitan urban and surrounding communities across the country and rural regions in the vicinity of oil and gas exploration activities (Schnell et al, 2009; EPA, 2011). The increase in the number and magnitude of fires is even more pronounced for forests in the western US (Westerling et al, 2006). Longer summers, which are driven by increasing temperatures, increase the fire ignition risk by 10-to-30% and are expected to increase burned areas by as much as 120% by the end of the century
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
