About

Nathan Lothrop, PhD, is an assistant research professor in the College of Public Health and the associate director of the BRISA Center for the Environment. He has nearly 15 years of collaborative environmental health and epidemiology research experience in academia and private consulting. His research focuses on community-engaged solutions to environmental health issues, with expertise in air pollution epidemiology, GIS and spatial analysis, social determinants of health, heavy metals exposures, research results reporting, and science communication. Prior to his current roles, he worked in photography and media, skills he applies to science communications. Nathan is committed to improving public health through responsible, team-based environmental health research and service. His notable awards include the Tucson Hispanic Chamber of Commerce 40-under-40 Award (2024), the International Society of Exposure Science JESEE Young Investigator Award (2019), and the College’s Community-Engaged Scholarship and Practice Award (2015).

Research topics

• Medicine
• Environmental protection
• Genetics
• Ecology
• Immunology
• Socioeconomics
• Environmental planning
• Psychology
• Biology
• Geography
• Pediatrics
• Demography
• Archaeology
• Environmental health

Selected publications

• Community health worker intervention to reduce worker exposure to volatile organic compounds in small business auto and beauty shops in a marginalized community: A cluster randomized controlled trial

  PLoS ONE · 2026-04-27

  articleOpen access

  BACKGROUND: Occupational diseases affect many workers in the United States, with Latinos disproportionately affected. Small businesses face barriers to implementing workplace health protections that community health workers (CHWs) may help overcome. The objective of this study was to determine whether a CHW-led industrial hygiene intervention could reduce volatile organic compound (VOC) exposure in small auto repair and beauty shops that primarily employ marginalized workers. METHODS: In this two-arm, parallel, cluster randomized trial, small business (≤25 employees) auto repair and beauty shops in Tucson, AZ were randomized to immediate or delayed intervention, stratified by sector. CHWs assessed shops and provided knowledge of controls and $300 for new ones. Total VOCs (TVOCs) were measured using photoionization detectors placed on or near participants. The primary outcome was the change in TVOCs at the shop level after the intervention, assessed across three timepoints with four workshift measurements per assessment. Mixed-effects models accounted for clustering by shop. RESULTS: We enrolled 38 auto repair shops and 46 beauty shops (73% Latino workers) and analyzed 846 workshift measurements at 236 shop assessments. Adjusted models showed a non-statistically significant intervention effect: auto shops experienced on average an estimated 28% TVOC increase (95% CI: -46% to 203%); beauty shops experienced on average an estimated 27% reduction (95% CI: -55% to 19%). Beauty shops had TVOC concentrations about 10 times higher than auto shops, and 87% of their assessments had ventilation rates below the recommended minimum. CONCLUSIONS: Although not statistically significant, the CHW-led intervention may meaningfully reduce VOC exposure in beauty shops. High TVOC concentrations and inadequate ventilation in beauty shops highlight the need for targeted interventions and policy changes to improve the air quality in these underserved small businesses. TRIAL REGISTRATION: This trial was registered with clinicaltrials.gov (NCT03455530) on March 6, 2018.

  PublisherDOI

• Characterizing full-shift worker exposures to VOCs in small-sized auto repair shops in the Tucson, Arizona, USA metropolitan area

  Scientific Reports · 2025-07-01 · 1 citations

  articleOpen access1st authorCorresponding

  Auto repair shops employ 1% of the US labor force. These workers are constantly exposed to volatile organic compounds (VOCs), which have known and often irreversible health effects, yet exposure studies are sparse. Our goal was to assess what exposure factors were related to total personal and shop-level specific VOC exposures for entire shifts in marginalized, predominantly Spanish-speaking workers in auto repair shops. Full-shift, real-time worker exposure factors like activities and ventilation conditions were recorded, along with personal total VOCs and shop-level specific VOC samples. The relationship of total VOCs with activity and ventilation, along with shift and shop, was analyzed using linear mixed effects modeling. Specific VOC concentrations were combined into hazard scores for potential health risks based on EPA inhalation reference or reference dose. Personal exposures were characterized by episodic peaks, with the highest peaks during spraying brake cleaner and painting activities in 22/35 shifts. Shift within shop and shop accounted for about half the variation in total VOC exposures to workers (35% and 15%, respectively), while activity and ventilation explained almost none. Acetone and toluene were detected in all samples. While worker exposure patterns were characterized by infrequent but very high peak exposures to total VOCs related to aerosolization activities, activities were only slightly predictive of VOC exposure overall. Instead, shift within shop and shop explained just half the variability. While additional study on exposure factors is needed, this should be done with a focus on interventions tailored to worker and shop.

  PublisherOA PDFDOI

• Creating a Structural Resource Prevention Index for Breast Cancer in a Southwestern US City with Historic Neighborhood Segregation

  medRxiv · 2025-12-03

  articleOpen access1st author

  Background Historically segregated neighborhoods in the United States continue to experience disproportionate health disparities, including cancer outcomes. The social vulnerability index (SVI) and similar indices are widely used to measure community disadvantage, but they do not directly capture contextual infrastructure relevant to cancer prevention. In Tucson, Arizona, where racially restrictive housing covenants, conditions, and restrictions (CCRs) remain as a legacy of segregation, we developed an alternative approach to assess neighborhood-level access to breast cancer prevention resources. Methods We developed the Structural Prevention Resources Index (SPRI), calculated as arithmetic mean of scores for access to free screening clinics, grocery stores with fresh produce, and parks. Each component was equally weighted to produce a composite score ranging from 1 (better access) to 6 (poorer access). We compared the SPRI to the Social Vulnerability Index (SVI). Results Drive-time analyses highlighted poor access to clinics providing free breast cancer screening for the eastern study area. Park access and quality were more evenly distributed with 56% of women ages 40-64 having access to high-quality parks. SPRI showed that minoritized women ages 40-64 more often resided in high or very high resource areas (67%) vs. non-minoritized women ages 40-64 (56%). SPRI captured geographic variation distinctly different than the SVI, notably a large central eastern portion of the study area with few prevention resources and low SVI scores. Conclusion Disease-specific indices such as SPRI can uncover structural barriers to chronic disease prevention, like breast cancer, often overlooked by general measures of geospatial vulnerability, offering more precise tools for guiding equitable public health planning and strategies. Highlights Develops the Structural Prevention Resource Index (SPRI) for breast cancer. Compares disease-specific index (SPRI) with the Social Vulnerability Index (SVI). Finds SPRI captures geographic disparities not reflected in SVI in Tucson, Arizona. Demonstrates value of disease-specific indices for public health planning.

  PublisherOA PDFDOI

• Disparities in the association of ambient air pollution with childhood asthma incidence in the ECHO consortium: A US-wide multi-cohort study

  Environmental Epidemiology · 2025-06-11 · 3 citations

  articleOpen access

  Background: Characterization of US sociodemographic disparities in air pollution respiratory effects has often been limited by lack of participant diversity, geography, exposure characterization, and small sample size. Methods: We included 34 sites comprising 23,234 children (born 1981-2021) from the Environmental influences on Child Health Outcomes (ECHO) Program with data on asthma diagnosis until age 10 (182,008 person-years). Predicted annual exposure to fine particulate matter (1988-2021), nitrogen dioxide (2000-2016), and ground ozone (2000-2016) were assigned based on residential histories. For each pollutant, we fitted time-varying Cox models adjusted for time trend, site, and several area- and individual-level sociodemographic features that were separately considered as modifiers via an interaction with exposure. Results: ), nitrogen dioxide (15.37 ppb), and ozone (6.87 ppb), respectively. For both fine particulate and nitrogen dioxide, children from areas with a higher proportion of Black residents or with a higher population density had greater pollution-associated risks of incident asthma. For ozone, asthma risks were enhanced in less dense areas. Conclusions: US efforts to mitigate childhood asthma risk by reducing air pollution would benefit from addressing root structural causes of vulnerability and susceptibility, including spatial patterning in air pollution sources and exposures as well as social and economic disadvantage.

  PublisherDOI

• Early-Life Exposure to Air Pollution and Childhood Asthma Cumulative Incidence in the ECHO CREW Consortium

  JAMA Network Open · 2024 · 72 citations

  • Medicine
  • Demography
  • Environmental health

  Importance: Exposure to outdoor air pollution contributes to childhood asthma development, but many studies lack the geographic, racial and ethnic, and socioeconomic diversity to evaluate susceptibility by individual-level and community-level contextual factors. Objective: To examine early life exposure to fine particulate matter (PM2.5) and nitrogen oxide (NO2) air pollution and asthma risk by early and middle childhood, and whether individual and community-level characteristics modify associations between air pollution exposure and asthma. Design, Setting, and Participants: This cohort study included children enrolled in cohorts participating in the Children's Respiratory and Environmental Workgroup consortium. The birth cohorts were located throughout the US, recruited between 1987 and 2007, and followed up through age 11 years. The survival analysis was adjusted for mother's education, parental asthma, smoking during pregnancy, child's race and ethnicity, sex, neighborhood characteristics, and cohort. Statistical analysis was performed from February 2022 to December 2023. Exposure: Early-life exposures to PM2.5 and NO2 according to participants' birth address. Main Outcomes and Measures: Caregiver report of physician-diagnosed asthma through early (age 4 years) and middle (age 11 years) childhood. Results: Among 5279 children included, 1659 (31.4%) were Black, 835 (15.8%) were Hispanic, 2555 (48.4%) where White, and 229 (4.3%) were other race or ethnicity; 2721 (51.5%) were male and 2596 (49.2%) were female; 1305 children (24.7%) had asthma by 11 years of age and 954 (18.1%) had asthma by 4 years of age. Mean values of pollutants over the first 3 years of life were associated with asthma incidence. A 1 IQR increase in NO2 (6.1 μg/m3) was associated with increased asthma incidence among children younger than 5 years (HR, 1.25 [95% CI, 1.03-1.52]) and children younger than 11 years (HR, 1.22 [95% CI, 1.04-1.44]). A 1 IQR increase in PM2.5 (3.4 μg/m3) was associated with increased asthma incidence among children younger than 5 years (HR, 1.31 [95% CI, 1.04-1.66]) and children younger than 11 years (OR, 1.23 [95% CI, 1.01-1.50]). Associations of PM2.5 or NO2 with asthma were increased when mothers had less than a high school diploma, among Black children, in communities with fewer child opportunities, and in census tracts with higher percentage Black population and population density; for example, there was a significantly higher association between PM2.5 and asthma incidence by younger than 5 years of age in Black children (HR, 1.60 [95% CI, 1.15-2.22]) compared with White children (HR, 1.17 [95% CI, 0.90-1.52]). Conclusions and Relevance: In this cohort study, early life air pollution was associated with increased asthma incidence by early and middle childhood, with higher risk among minoritized families living in urban communities characterized by fewer opportunities and resources and multiple environmental coexposures. Reducing asthma risk in the US requires air pollution regulation and reduction combined with greater environmental, educational, and health equity at the community level.

  PublisherOA PDFDOI

• The Legacy of Redlining: Increasing Childhood Asthma Disparities through Neighborhood Poverty

  American Journal of Respiratory and Critical Care Medicine · 2024-06-13 · 26 citations

  articleOpen access

  Abstract Rationale Identifying the root causes of racial disparities in childhood asthma is critical for health equity. Objectives To determine whether the racist policy of redlining in the 1930s led to present-day disparities in childhood asthma by increasing community-level poverty and decreasing neighborhood socioeconomic position (SEP). Methods We categorized census tracts at the birth address of participants from the Children’s Respiratory and Environmental Workgroup birth cohort consortium into categories A, B, C, and D as defined by the Home Owners Loan Corporation, with D being the highest perceived risk. Surrogates of present-day neighborhood-level SEP were determined for each tract, including the percentage of low-income households, the CDC’s Social Vulnerability Index, and other tract-level variables. We performed causal mediation analysis, which, under the assumption of no unmeasured confounding, estimates the direct and mediated pathways by which redlining may cause asthma disparities through tract-level mediators adjusting for individual-level covariates. Measurements and Main Results Of 4,849 children, the cumulative incidence of asthma through age 11 was 26.6%, and 13.2% resided in census tracts with a Home Owners Loan Corporation grade of D. In mediation analyses, residing in Grade-D tracts (adjusted odds ratio = 1.03 [95% confidence interval = 1.01, 1.05]) was significantly associated with childhood asthma, with 79% of this increased risk mediated by percentage of low-income households; results were similar for the Social Vulnerability Index and other tract-level variables. Conclusions The historical structural racist policy of redlining led to present-day asthma disparities in part through decreased neighborhood SEP. Policies aimed at reversing the effects of structural racism should be considered to create more just, equitable, and healthy communities.

  PublisherOA PDFDOI

• Environmental and structural factors associated with bacterial diversity in household dust across the Arizona-Sonora border

  Scientific Reports · 2024-06-04 · 3 citations

  articleOpen access

  We previously reported that asthma prevalence was higher in the United States (US) compared to Mexico (MX) (25.8% vs. 8.4%). This investigation assessed differences in microbial dust composition in relation to demographic and housing characteristics on both sides of the US-MX Border. Forty homes were recruited in the US and MX. Home visits collected floor dust and documented occupants' demographics, asthma prevalence, housing structure, and use characteristics. US households were more likely to have inhabitants who reported asthma when compared with MX households (30% vs. 5%) and had significantly different flooring types. The percentage of households on paved roads, with flushing toilets, with piped water and with air conditioning was higher in the US, while dust load was higher in MX. Significant differences exist between countries in the microbial composition of the floor dust. Dust from Mexican homes was enriched with Alishewanella, Paracoccus, Rheinheimera genera and Intrasporangiaceae family. A predictive metagenomics analysis identified 68 significantly differentially abundant functional pathways between US and MX. This study documented multiple structural, environmental, and demographic differences between homes in the US and MX that may contribute to significantly different microbial composition of dust observed in these two countries.

  PublisherOA PDFDOI

• What a mix! Volatile organic compounds and worker exposure in small business beauty salons in Tucson, Arizona

  Frontiers in Public Health · 2023-12-18 · 3 citations

  articleOpen access

  Introduction: Small business beauty salons have volatile organic compounds (VOCs) in their workplace air. VOCs are present as ingredients in beauty or hair products. They may also form because of chemical reactions, where thermal-styling elements accelerate the volatilization of these compounds. Uncertainties remain about the relationship between air pollutant concentrations and the variety of beauty salon activities in a work shift. Investigating these associations can help determine high-risk services, associated products, and at-risk workers. Methods: In this exploratory study, female community health workers recruited beauty salons from target zip codes in predominately Latino neighborhoods, including primarily Spanish-speaking small businesses. We collected salon chemical inventories, business characteristics, and participant activity logs to understand how chemicals and activities influence the total and specific VOC concentrations. We sampled personal total VOCs and specific VOCs from the same shop during the participant work shift. We also measured personal total VOCs for four work shifts per shop. Results: A linear mixed effects model of log VOCs on the fixed effect of activity and the random effects of salon and shift within the salon showed that the variance between salons explains over half (55%) of the total variance and is 4.1 times bigger than for shifts within salons. Summa canisters detected 31 specific VOCs, and hazard scores ranged between 0 and 4.3. 2-Propanol (isopropyl alcohol) was the only VOC detected in all shifts of all salons. Discussion: In this study, differences in VOC measurements were primarily between salons. These differences may result from differences in ventilation, services rendered, and product lines applied.

  PublisherOA PDFDOI

• Environmental and Structural Factors Associated with Bacterial Diversity in Household Dust Across the Arizona-Sonora Border

  Research Square · 2023-09-29 · 1 citations

  preprintOpen access

  <title>Abstract</title> We previously reported that asthma prevalence was higher in the United States (US) compared to Mexico (MX) (25.8% vs 8.4%). This investigation assessed differences in microbial dust composition in relation to demographic and housing characteristics on both sides of the US-MX Border. Forty homes were recruited in the US and MX. Home visits collected floor dust and documented occupants’ demographics, asthma prevalence, and housing structure and use characteristics. US households were more likely to have inhabitants who reported asthma when compared with MX households (30% vs 5%) and had significantly different flooring types. The percentage of households on paved roads, with flushing toilets, with piped water and with air conditioning was higher in the US, while dust load was higher in MX. Significant differences exist between countries in the microbial composition of the floor dust. Dust from US homes was enriched with <italic>Geodermatophilus</italic>, whereas dust from Mexican homes was enriched with <italic>Alishewanella</italic> and <italic>Chryseomicrobium</italic>. A predictive metagenomics analysis identified 68 significantly differentially abundant functional pathways between US and MX. This study documented multiple structural, environmental, and demographic differences between homes in the US and MX that may contribute to significantly different microbial composition of dust observed in these two countries.

  PublisherOA PDFDOI

• A Community-Based Health Risk Assessment Following the Gold King Mine Spill: Results from the Gold King Mine Spill Diné Exposure Project

  Exposure and Health · 2023-07-06 · 6 citations

  articleOpen access
  PublisherOA PDFDOI

Frequent coauthors

• Paloma I. Beamer

  University of Arizona

  41 shared

• Miranda Loh

  Institute of Occupational Medicine

  18 shared

• Fernando D. Martínez

  University of Arizona

  14 shared

• Diane R. Gold

  Harvard University

  12 shared

• Walter T. Klimecki

  12 shared

• Anastasia Sugeng

  11 shared

• Sarah T. Wilkinson

  10 shared

• Dean Billheimer

  University of Arizona

  9 shared

Awards & honors

• Tucson Hispanic Chamber of Commerce 40-under-40 Award (2024)
• International Society of Exposure Science JESEE Young Invest…
• College’s Community-Engaged Scholarship and Practice Award (…