atmosphere Article Sources of Formaldehyde in Bountiful, Utah Nitish Bhardwaj 1, Ariel Kelsch 1, Delbert J. Eatough 1, Ryan Thalman 2 , Nancy Daher 3, Kerry Kelly 4 , Isabel Cristina Jaramillo 4 and Jaron C. Hansen 1,* 1 Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA;
[email protected] (N.B.);
[email protected] (A.K.);
[email protected] (D.J.E.) 2 Department of Chemistry, Snow College, Richfield, UT 84701, USA;
[email protected] 3 Utah Division of Air Quality, Salt Lake City, UT 84116, USA;
[email protected] 4 Chemical Engineering, University of Utah, Salt Lake City, UT 84112, USA;
[email protected] (K.K.);
[email protected] (I.C.J.) * Correspondence:
[email protected]; Tel.: +1-801-422-4066 Abstract: The U.S Environmental Protection Agency’s National Air Toxics Trends Stations Network has been measuring the concentration of hazardous air pollutants (HAPs) including formaldehyde (HCHO) since 2003. Bountiful, Utah (USA) has served as one of the urban monitoring sites since the network was established. Starting in 2013, the mean concentration of HCHO measured in Bountiful, Utah exceeded the non-cancer risk threshold and the 1 in 1 million cancer risk threshold. In addition, the measured concentrations were more than double those found at surrounding locations in Utah. A Positive Matrix Factorization (PMF) analysis using PMF-EPA v5 was performed using historical data (2004–2017) to better understand the sources of formaldehyde in the region. The historical data set included samples that were collected every sixth day on a 24 h basis.