Correction to: Hazardous air pollutant emissions estimates from wildfires in the wildland urban interface

This is a correction to:

Amara L Holder, Aranya Ahmed, Jeffrey M Vukovich, Venkatesh Rao, Hazardous air pollutant emissions estimates from wildfires in the wildland urban interface, PNAS Nexus, Volume 2, Issue 6, June 2023, pgad186, https://doi.org/10.1093/pnasnexus/pgad186

Several unit conversion errors were made when transcribing emission factors from two references into the WUI emission factor compilation. These errors led to the PAH emissions for vehicle fires to be incorrectly inflated by three orders of magnitude, which resulted in large emission estimates for all of the WUI fires. With the correct PAH emissions data WUI fire emissions for the affected PAH species are 4 – 10% of the original emission estimates.

These errors led to the incorrect conclusion that WUI fuels dominated PAH emissions for most of the fires analyzed. Using the correct emission factors and recalculating the analysis resulted in only one fire – the Tubbs Fire – which had WUI Fire PAH emissions were greater than those from the Fire category. However, the corrected WUI fire PAH emissions are still greater than or equal to those from the Other category.

Description of Errors

Unit conversion errors were made when transcribing emission factor data from the following references into the emission factor compilation spreadsheet:

1. PAH emission factors for the reference Fiani et al. 2018 INERIS- DRC-13-119925-05193A were entered into the emission factor compilation with incorrect units of mg/kg instead of the correct units of g/kg. This resulted in three emission factor observations (out of five) in the vehicle category to be 1,000 times greater than the other emission factors in the vehicle category. This translated to an error in the median PAH emission factors for the Vehicle category for these compounds, which was propagated throughout the emission estimates in the paper. The implications of this error are described further below.

   The PAHs impacted were:

   • Naphthalene

   • Acenaphthene

   • Acenaphthylene

   • Fluorene

   • Phenanthrene

   • Anthracene

   • Fluoranthene

   • Pyrene

   • Benzo(a)anthracene

   • Chrysene

   • Benzo(b)fluoranthene

   • Benzo(k)fluoranthene

   • Benzo(a)pyrene

   • Indeno(1,2,3-c,d)pyrene

   • Benzo(g,h,i)perylene

   • Dibenzo(a,h)anthracene

2. Benzo(a)pyrene emission factors for the reference SP Report 2005:42 was entered into the emission factor compilation with incorrect units of mg/kg instead of the correct units of g/kg. This resulted in three emission factor observations (out of eleven) in the Electronics category to be 1,000 times greater than the other emission factors in the Electronics category. This error only impacted Figure 1-F for the Electronics category.

Additionally, the ‘Reference DOI or Report No.’ was incorrect in Table S1 on rows 327 through 338. The correct reference is RISE Report 2018:40.

Figure Corrections

The analysis has been redone with the correct emission factor data impacting the following figures:

• Figure 1 F – has the correct emission factors displayed for Electronics and Vehicle categories for benzo(a)pyrene. Corrected figure is shown below.

• Figure 2 – has the correct emission factors for the Vehicle category for the PAH compounds. The corrected figure is shown below.

• Figure 4 – has the correct emissions for benzo(a)pyrene. The corrected figure is shown below.

• Figure 5 – has the correct emissions ratio for all PAH to Fire and to Other Sources. The corrected figure is shown below.

And the supplemental data, noted by the yellow highlighted cells in each table in the attached excel spreadsheet:

• Table S1 Emission factor observations for urban materials

• Table S2 Median emission factor by species for structures and vehicles compared to average biomass value in SERA

• Table S3 Emissions information for all fires and categories

These details have been corrected only in this correction notice to preserve the published version of record.