Gradient Principal Environmental Consultants

Christopher M. Long, Sc.D.

Dr. Long is an expert in the area of indoor and outdoor air quality, with particular expertise in exposure assessment, inhalation toxicology, air pollution epidemiology, air sampling and measurement, and air modeling. He has assessed exposures and health risks associated with airborne particulates such as diesel exhaust particulates, carbon black, latex aeroallergens, ambient sulfates and nitrates, sulfuric acid, asbestos, ambient ultrafines, engineered nanoparticles, lead and other trace elements, bioaerosols and a number of gaseous criteria and hazardous air pollutants including carbon monoxide, ozone, hydrogen sulfide, sulfur dioxide, and benzene. Dr. Long’s practice area includes evaluating product safety, with specific interests in airborne exposures and engineered nanoparticles, and he is a technical editor of Gradient’s nanotechnology newsletter, EH&S Nano News. Dr. Long also has a particular interest in the historical evolution of air pollution science and regulation.

Dr. Long has prepared approximately 20 technical papers for publication in peer-reviewed journals in the general areas of indoor and outdoor air pollution and exposure assessment. He is a member of the International Society of Exposure Science, the Air and Waste Management Association, and the American Chemical Society.

Representative Projects

Air Toxics Health Risk Characterization: At the request of the New Mexico Environment Department (NMED), prepared a community acute health risk assessment associated with inhalation exposures to over 80 air toxics using air monitoring and modeling data.

Air Quality Impacts at a Confined Animal Feeding Operation (CAFO):  Conducted air sampling and performed air dispersion modeling analysis to characterize the air quality impacts of hydrogen sulfide (H2S) gas emissions at a large Midwestern hog farm.

Coal Ash Risk Assessment and Public Communications: For a utility company, prepared a multi-pathway human health risk assessment evaluating potential exposures of nearby residents to a coal ash disposal site.  Prepared a white paper on coal ash for public dissemination.

Commercial Printer Product Safety Evaluation: Designed a comprehensive measurement program to assess potential exposures associated with the use of a commercially available printer. Assessed toxicological significance of indoor air and surface wipe measurements.

Indoor/Outdoor PM2.5 Sampling and Exposure Assessment: Designed and implemented an indoor/outdoor PM2.5 sampling program in residential homes near a large industrial facility to investigate source contributions to individual particulate matter exposures.

Human Health Risk Assessment for a Biomass-burning Power Plant: Prepared a human health risk assessment to support the permitting process for a biomass burning power plant.  Assessed potential cancer and non-cancer risks from inhalation of criteria air pollutants and air toxics in stack and fugitive emissions from the plant; evaluated potential health risks associated with mercury deposition and accumulation in fish.



Selected Publications

Hesterberg, TW; Long, CM; Bunn, WB; Lapin, CA; McClellan, RO; Valberg, PA. 2012. "Health effects research and regulation of diesel exhaust: An historical overview focused on lung cancer risk." Inhal. Toxicol. 24: 1-45.

Hesterberg, TW; Long, CM; Lapin, CA; Hamade, AK; Valberg, PA. 2010. "Diesel exhaust particulate (DEP) and nanoparticle exposures: What do DEP human clinical studies tell us about potential human health hazards of nanoparticles?" Inhal. Toxicol. 22: 679-694.

Valberg, P; Long, CM. 2010. "Do brain cancer rates correlate with ambient exposure levels of criteria air pollutants or hazardous air pollutants (HAPs)?" Air Qual. Atmos. Health 5: 115-123.

Valberg, P; Long, CM; Sax, SN. 2006. "Integrating studies on carcinogenic risk of carbon black: Epidemiology, animal exposures, and mechanism of action." J. Occup. Environ. Med. 48: 1291-1307.




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