Neil Crain

Ventilation and indoor air quality in retail stores: A critical review (RP-1596)

Identifying air pollutants that pose potential adverse health exposures in retail stores will facilitate exposure mitigation. Assessing the role of ventilation in mitigating this exposure is important to understand the energy implications of maintaining acceptable indoor air quality. In this work, we summarize results from 28 papers that report ventilation rates and/or pollutant concentrations in retail stores. These results were compared to available standards as well as data collected in non-retail environments. The findings of this review are: (1) half of the stores tested met/exceeded ASHRAE Standard 62.1-2010 (ASHRAE 2010a; or California Code of Regulations Title 24-2010) for ventilation; (2) PM2.5, acrolein, formaldehyde, and acetaldehyde exceeded their established, most conservative limits/reference exposures for a few of the stores tested in the United States, and outside the United States, researchers reported PM10, benzene, and trichloroethylene as additional pollutants found at concentrations that exceeded their limits; (3) alternative control methods would be more effective, and possibly more economical, than ventilation; (4) meeting or exceeding the ventilation requirements does not necessarily negate the presence of pollutants above their suggested limits; and (5) using disability-adjusted-life-year (DALY) as a metric of disease burden, two pollutants were identified as priority hazards in retail stores: PM2.5 and acrolein. Control strategies should focus on decreasing exposure of retail employees to these pollutants generated indoors or infiltrated from outdoors.

Field evaluation of five volatile organic compound measurement techniques: Implications for green building decision making

Measurements of volatile organic compounds can be necessary to ensure healthy indoor environments. Many methods exist to collect and analyze volatile organic compounds, and each technique is associated with characteristic issues that affect the identification and quantification of some volatile organic compounds. In this study, simultaneous samples of volatile organic compounds were collected during 30 test visits in 14 retail stores. Time-integrated measurements were made using Summa canisters, Tenax-GR sorbent tubes, and 2,4-dinitrophenylhydrazine tubes. Time-resolved measurements were collected using photoionization detectors and colorimetric formaldehyde multimode monitors. Sampling with Summa canisters is less field intensive than with sorbent tubes; however, samples collected using Tenax-GR sorbent tubes indicated more possible exceedances of health guidelines compared to Summa canister samples. Photoionization detector total volatile organic compound concentrations were not directly correlated with Summa canister results even after correction for differential response to different volatile organic compounds. Formaldehyde monitor results were strongly correlated with 2,4-dinitrophenylhydrazine tube results for formaldehyde, and the two sampling techniques agreed on all exceedances of the National Institute for Occupational Safety and Health (NIOSH) chronic recommended exposure limit (16 ppb) but not on exceedances of the stricter Office of Environmental Health Hazard Assessment chronic recommended exposure limit (7.3 ppb) at two stores. The formaldehyde monitor showed promising characteristics, supporting its further consideration as an indicator to control ventilation and/or environmental parameters in buildings where formaldehyde concentrations are of concern. The variation in results from various volatile organic compound sampling approaches can lead to different compliance levels with green building standards for a single building.

Influence of environmental factors on removal of oxides of nitrogen by a photocatalytic coating

Nitrogen oxides (NOx) emitted from combustion processes have elevated concentrations in large urban areas. They cause a range of adverse health effects, acid rain, and are precursors to formation of other atmospheric pollutants, such as ozone, peroxyacetyl nitrate, and inorganic aerosols. Photocatalytic materials containing a semi-conductor that can be activated by sunlight, such as titanium dioxide, have been studied for their ability to remove NOx. The study presented herein aims to elucidate the environmental parameters that most influence the NOx removal efficiency of photocatalytic coatings in hot and humid climate conditions. Concrete samples coated with a commercially available photocatalytic coating (a stucco) and an uncoated sample have been tested in a reactor simulating reasonable summertime outdoor sunlight, relative humidity and temperature conditions in southeast Texas. Two-level full factorial experiments were completed on each sample for five parameters. It was found that contact time, relative humidity and temperature significantly influenced both NO and NO2 removal. Elevated concentrations of organic pollutants reduced NO removal by the coating. Ultra-violet light intensity did not significantly influence removal of NO or NO2, however, ultra-violet light intensity was involved in a two-factor interaction that significantly influenced removal of both NO and NO2. Implications: The potential for removal of oxides of NOx in realistic outdoor conditions by a photocatalytic coating (a stucco) applied on concrete was studied through full factorial experimentation. Results suggest that locations offering longer contact time between the pollutant and the reactive surface would lead to greater removal. The presence of elevated relative humidity reduces the NOx removal effectiveness of the coating. Concentrations of organic pollutants in the vicinity of the material did not significantly influence its removal effectiveness, making it potentially suitable as a control strategy for NO2 near roadways, where elevated NO2 levels are observed in combination with volatile organic compounds (VOCs).