Indoor air quality investigation and health risk assessment at correctional institutions

Abstract

A comprehensive indoor air–quality (IAQ) investigation was conducted at a state correctional facility in New Jersey, USA with a lengthy history of IAQ problems. The IAQ investigation comprised preliminary indoor air screening using direct readout instrumentation, indoor air/surface wipe sampling and laboratory analysis, as well as a heating, ventilation, and air-conditioning system evaluation, and a building envelope survey. In addition to air sampling, a human health risk assessment was performed to evaluate the potential for exposure to site-related air contaminants with respect to the inmate and worker populations. The risk assessment results for the prison facility indicated the potential for significant health risks for the inmate population, possibly reflecting the effects of their confinement and extended exposure to indoor air contaminants, as compared to the prison guard and worker population. Based on the results of the risk assessment, several mitigation measures are recommended to minimize prison population health risks and improve indoor air quality at prison facilities.

INTRODUCTION

A correctional institution in New Jersey, USA was constructed approximately 20 y ago on reclaimed tidal marshland that previously received city sanitation waste and stormwater drainage. Landfill and illegal waste–dumping activities also were reported to have occurred at the site in the past. Several health complaints possibly related to poor indoor air quality (IAQ) were documented by both the prison inmates and workers beginning a few years after the prison facility became operational. Complaints ranged from eye tearing, respiratory distress, facial/skin rashes, and irritation to headaches, nausea, and vomiting. In response to the complaints, several indoor air–sampling investigations were conducted at different locations within the facility. Most of the sampling results were reported as below American Conference of Governmental Industrial Hygienists threshold limit values (ACGIH 2003), as well as other federal- and state-recommended air-quality guideline values. Several IAQ inspections also were performed by New Jersey Public Employees Occupational Safety and Health Program (PEOSH) inspectors. The PEOSH inspections found poor heating, ventilation, and air-conditioning (HVAC) maintenance habits and generally shoddy housekeeping, but reported no significant violations of the PEOSH IAQ standard. However, the IAQ problems continued and probable causes and potential remedies remain unresolved.

The PEOSH IAQ standard (New Jersey Administrative Code 12:100–13), which became effective in March 1997, requires public employers to provide employees with acceptable IAQ at the work place. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers defines acceptable IAQ as “air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.” The PEOSH IAQ standard describes the steps and procedures that public employers should implement to comply with the requirements of the standard. According to PEOSH, most IAQ health problems can be categorized either as sick building syndrome or building-related illnesses. Sick building syndrome is associated with the situation where a large number of building occupants experience health and comfort problems that cannot be attributed to any particular illness or sources, and that seem to disappear upon leaving the building (PEOSH 1996). Sick building syndrome symptoms include headaches; eye, nose, or throat irritation; itchy skin; and loss of concentration. Building-related illnesses are associated with the situation where a relatively small number of building occupants experience health problems or symptoms that are not necessarily alleviated by leaving the building (PEOSH 1996). This condition generally is caused by allergic reactions to microbial contamination and/or specific chemical or biological exposure to substances such as carbon monoxide, formaldehyde, pesticides, bacterial endotoxins, or mycotoxins. Illnesses and symptoms may include asthma; Legionnaires' disease; eye, nose, or throat irritation; skin irritation or rashes; chills; congestion; muscle aches; and pneumonia. Based on a review of the documented IAQ complaints at the prison facility, it appeared that IAQ-related health problems among inmates and prison workers could be characterized as either sick building syndrome or building-related illness.

In a concerted effort to determine whether site-related contaminants were the cause of the IAQ problems at the prison and to achieve a final resolution of the matter, the New Jersey Department of Corrections commissioned a comprehensive soil, water, and ambient air investigation of the facility. The work also included a health–risk assessment to evaluate potential health risks for the prison worker and inmate populations. The IAQ sampling investigation was conducted to determine the presence and concentrations of indoor contaminants that might adversely impact the health and well being of workers and inmates. The IAQ air-sampling approach and results are summarized in this paper. The health–risk assessment, using indoor air-contaminant concentrations measured at the prison as receptor exposure point concentrations, also is presented. The results of the health–risk assessment are summarized and used to support recommendations for improving air quality at prison facilities.

INDOOR AIR–SAMPLING METHODS AND RESULTS

IAQ sampling methods

The IAQ investigation included preliminary indoor-air screening using direct reading instruments; indoor-air sampling and laboratory analysis for airborne chemical and microbial contaminants; surface wipe sampling for deposited contaminants; an HVAC system evaluation; and a building envelope survey to identify potential areas of moisture infiltration. A preliminary screening of the indoor air at various locations within the facility was performed to determine general ambient conditions and locate potential airborne contamination hot spots. These hot spots were targeted for follow-up sampling and further investigation, as necessary. The preliminary air-screening survey was performed using direct reading air instrumentation, which included a photo-ionization detector, a flame-ionization detector, and a multiparameter air-monitoring instrument. These instruments screen the ambient indoor air for carbon dioxide, carbon monoxide, oxygen, hydrogen sulfide, methane, volatile organic compounds (VOCs), temperature, relative humidity, and the lower explosive limit. The outdoor air also was screened for the same parameters to provide a baseline for comparative purposes. The air-screening results were compared to U.S. Environmental Protection Agency (USEPA) and New Jersey Department of Environmental Protection ambient air-monitoring concentrations in the vicinity of the site, as well as PEOSH and American Society of Heating, Refrigerating, and Air-Conditioning Engineers guideline values. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers IAQ guidelines referenced in this paper are regarded as comfort parameters, within which approximately 80% of a given building population will not have complaints concerning IAQ.

Indoor air samples were collected from selected sampling locations within the facility and submitted to a certified laboratory under established chain of custody procedures. A total of 65 sampling locations were selected at 17 prison building locations. Eleven of the 17 buildings were inmate housing units, and the remaining buildings were used for administration, hospital, kitchen/dining, and chapel services. The sampling locations were selected to provide broad coverage indoor air–quality conditions at the facility. The air-screening results indicated the worst indoor air quality occurred at the facility infirmary; 4 sampling stations were established here to provide adequate evaluation of this location. Indoor air sampling included low-volume air sampling for semivolatile organic chemicals (SVOCs), metals (including mercury), VOCs, and fixed gases (including methane) using summa canisters. Surface wipe sampling was performed for SVOCs, polychlorinated biphenyls (PCBs), and metals; microbial air sampling was performed for total fungal spore counts. Morning and afternoon samples were collected at each sampling location in order to evaluate a potential time-dependency factor for any identified IAQ problems. Additional morning and afternoon samples were collected from selected outdoor locations for baseline comparisons. On average, 2 outdoor locations were sampled on each day of sampling and each parameter type sampled. Quality assurance/quality control samples, consisting of field blanks (unsampled media) and blind duplicate samples, also were collected. The same sampling pumps and laboratory-supplied sampling media were used throughout the sampling episode.

Low-volume air sampling for SVOCs was conducted at each sampling location using low-volume air sampling pumps placed at approximate breathing-zone height (approximately 4–6 feet above the floor). The low-volume pumps were calibrated to a flow rate of approximately 2 to 3 L/min, and samples were collected on XAD-2 tubes supplied by the analytical laboratory. Two samples were collected at each sampling location, with 1 sample collected during the morning hours of 8:00 AM to 12:00 PM, and 1 sample collected during the afternoon hours of 12:00 to 4:00 PM. Samples were tested for SVOCs using National Institute for Occupational Safety and Health Modified Method 5515.

Low-volume air sampling for metals was conducted at each sampling location using low-volume air sampling pumps placed at breathing-zone height. Two discrete samples were collected at each location: Samples for priority pollutant metals (PPM) analysis were collected and tested using USEPA Methods 6010B and 3050, and samples for mercury analysis were collected and tested using National Institute for Occupational Safety and Health Modified Method 6009. The low-volume pumps were calibrated to a flow rate of 0.25 L/min for mercury samples and a flow rate of 3 to 4 L/min for PPM samples. Low-volume samples for mercury were collected on hopcholite (6009M) tubes. Low-volume samples for metals other than mercury were collected on mixed-cellulose ester filter cassettes. One morning and 1 afternoon sample were collected at each sampling location, similar to the approach used to sample SVOCs.

Active air sampling for VOCs was performed by placing 6-L stainless steel summa canisters at breathing-zone level at each of the selected sampling locations. The canisters were preset by the laboratory to a negative pressure of 30 inches of water, and timed for 24-h sample collection. Building occupants were instructed to avoid smoking, burning incense, or releasing other airborne substances that might impact the ambient air during the 24-h sample collection period. Summa canisters were submitted to the laboratory for VOC analysis by USEPA Method TO-15.

Sampling for microbial contamination was performed at each sampling location using high-volume air-sampling pumps calibrated to a flow rate of 15 L/min while connected to an Air-O-Cell cassette supplied by the laboratory. At each sampling location, the pumps were operated for approximately 5 min to draw a total air volume of 75 L. The Air-O-Cell cassette was designed for collection of a wide array of aerosols, such as mold spores, pollen, airborne fibers, and microbial cell fragments. The airborne aerosol particles were pulled into the cassette and fixed on a transparent adhesive slide in the center of the cassette. The slide was examined microscopically at the laboratory to determine approximate airborne fungal spore counts. The microbial air sampling served as a general indicator of total airborne spore counts and was capable of identifying spore genera, but not spore species or viability (capable of growth).

Three separate surface wipe samples were collected at each of the selected sampling locations for PPM, SVOC, and PCB analyses. Wipe samples for PPM analysis were collected on sterile gauze wipes treated with a weak nitric acid solution. Wipe samples for SVOCs and PCB analyses samples were collected on sterile gauze pads treated with hexane. The SVOC, PPM, and PCB analyses were conducted using USEPA Methods 8270C, 6010B, and 8082, respectively.

Ambient air-screening results

The PEOSH guideline concentration limit of 1,000 parts per million (ppm) for carbon dioxide was exceeded at several locations within the facility, with a maximum detected concentration of 3,058 ppm. Elevated levels of carbon monoxide (up to 7.2 ppm) also were detected. These levels did not exceed USEPA national ambient air quality standards for carbon monoxide, but most of the results exceeded background average carbon monoxide concentration recorded at nearby USEPA and New Jersey Department of Environmental Protection ambient air-monitoring stations. Low levels of methane (up to 19.8 ppm), VOCs (up to 4.6 ppm), and hydrogen sulfide (up to 6 ppm) also were detected in ambient air, although the levels did not exceed any known guideline concentration limits and were below ambient outdoor levels. The highest concentrations of most of the indicated parameters were detected at the same area of the prison facility, namely the infirmary.

Indoor air-sampling results

Indoor air sampling and laboratory analysis detected low concentrations of VOCs and various metals at several locations across the facility, as well as elevated fungal spore counts at a few locations. The sampling results showed a site-wide distribution, and did not indicate certain buildings or sections of buildings at the prison as potential risk source areas. The results for the infirmary area, which was identified as a potential IAQ problem area based on the elevated air-screening parameter readings, showed elevated trichloroethylene concentrations at all 4 sampling locations and elevated benzene concentrations at 3 of 4 sampling locations. However, comparable concentrations also were found at other sampling locations, especially in the inmate housing areas. Therefore, while the infirmary air-screening results might suggest poor air circulation, the air-sampling results did not support a conclusion that the infirmary was the only or main risk source area. With respect to potential temporal trends in airborne contaminant concentrations, a definitive trend in contaminant concentrations between the morning and the afternoon sampling periods could not be established. Surface wipe sampling did not detect PCBs or SVOCs above the laboratory method detection limits. However, low concentrations of various metals were detected at several locations across the facility.

Benzene (up to 4.8 μg/m³), trichloroethylene (up to 59 μg/m³), and tetrachloroethylene (up to 160 μg/m³) consistently were detected in the majority of the buildings sampled. None of the 3 VOCs exceeded U.S. Occupational Safety and Health Administration–permissible exposure levels (PELs) for occupational exposure (NIOSH 2003). The 3 VOCs, along with several other VOCs (including chloroform [up to 9.3 μg/m³] and, to a lesser extent, 1,3-butadiene [up to 2.7 μg/m³]), were detected in several buildings at levels that exceeded USEPA (2003) Region 3 ambient air risk-based concentrations for residential exposure (USEPA 2003). In addition, the gasoline range volatile organics (specifically, xylene, toluene, and ethylbenzene) were detected widely at the prison, but at levels that were below both U.S. Occupational Safety and Health Administration PEL and USEPA (2003) risk-based concentration values. Metals detected in several of the air samples included thallium, cadmium, beryllium, chromium, lead, copper, zinc, and mercury. None of the metals detected exceeded U.S. Occupational Safety and Health Administration PEL values. However, 4 metals, namely beryllium (up to 0.13 μg/m³), cadmium (up to 0.13 μg/m³), thallium (up to 1.3 μg/m³), and mercury (up to 1.8 μg/m³), were detected at concentrations that exceeded USEPA (2003) Region 3 ambient air risk-based concentrations. Regarding the surface wipe sampling results, the only regulatory standard available for metals concentrations is the USEPA lead criteria (40 μg/cm²). None of the lead concentrations detected in the wipe samples exceeded the USEPA criteria. The PCB concentrations in all wipe samples were not detected (ND). The outdoor air sample results included low concentrations of chloromethane, chromium, n-hexane, toluene, xylenes, and zinc.

Total fungal spore counts at 3 sampling locations were 4,320/m³, 1,140/m³, and 1,223/m³, respectively. The American Conference of Governmental Industrial Hygienists suggests that a spore count of up to 10 times the count in nonsuspect areas might indicate unusual fungal amplification at a site. The spore counts at all other sampled locations generally were in the low hundreds and comparable with outdoor air. The results did not indicate unusual fungal amplification.

HEALTH RISK-ASSESSMENT METHODS AND RESULTS

Risk-assessment methods

The risk assessment was performed by quantifying carcinogenic and noncarcinogenic health risks that potentially are attributable to detected airborne contaminant exposure. The risk assessment was based on 2 sets of exposure characteristics considered appropriate for either the prison worker or the inmate populations. The main differences between worker and inmate population exposure characteristics are the amount of time spent indoors and the number of years spent at the prison facility. Inmates are considered to be full-time residents for the duration of time that they are incarcerated, and are expected to spend the bulk of their time during this period indoors. In contrast, prison workers occupy the facility only during their 8- or 10-h work shifts. The contaminant concentrations to which both populations potentially are exposed are the same because workers, guards, and inmates almost always occupy the same buildings. Other exposure assumptions summarized in Table 1, such as average time spent indoors, inmate incarceration duration, worker occupational tenure, body weight, inhalation rate, and exposure frequency, are based on USEPA default exposure assumptions (USEPA 1997). In addition to the average exposure scenario, worst-case exposure scenarios for both the worker and inmate populations were evaluated. For each exposure factor, the average value was assumed equivalent to the USEPA 50th percentile, while the worst-case value was assumed equivalent to the 95th percentile. Presenting a range of risk estimates, rather than single point values, underscores the variability and uncertainty typically associated with exposure modeling and risk assessments. Variability and uncertainty in health risk assessments arise from natural variability in exposure characteristics among the receptor populations, as well as lack of full knowledge regarding important factors that affect the risk estimates (NRC 1994; USEPA 1995).

Table Table 1.. Assumed exposure factors used for the risk assessment. Exposure factors were based on U.S. Environmental Protection Agency Exposure Factors Handbook and the risk assessor's judgment. The inmate population is predominantly black and male. The worker population is mixed, both racially and gender-wise. If no data is available for the 95th percentile value, the average value is used

	Worker population		Inmate population
Exposure factor	Average value	95th percentile value	Average value	95th percentile value
Inhalation rate ([IH] m^3/h)	0.55	No data	0.633	No data
Exposure time ([ET] h/d)	7	9	20	22
Body weight ([BW] kg)	75	105.2	75.3	105.4
Exposure frequency ([EF] d/y)	250	260	365	365
Exposure duration ([ED] y)	6.6	15	10	20
Averaging time ([AT] y)	75	79	70	75
Bioavailability ([Bs] dimensionless)	1	1	1	1

The risk assessment was performed in accordance with USEPA human health risk-assessment guidance (USEPA 1989, 2003), and aided by use of the American Petroleum Institute's Decision Support System model (API 1999). American Petroleum Institute's Decision Support System was used to perform the contaminant intake and risk quantification calculations and generate the results. The calculated risk estimates apply to the hypothetical individual member of the specified receptor population, rather than specific individuals within the population.

Although air contaminants were not found in every section of each of the potentially affected buildings (indeed the results were ND for the majority of locations sampled), it was deemed neither practical nor prudent to identify contaminated and clean buildings and to perform the risk assessment separately for each section of an affected building. The absence of measurable air contaminants in some buildings or building sections was assumed not necessarily to indicate absence of poor IAQ. For these reasons, it was assumed conservatively that air contaminants occur site-wide and the risk assessment was performed based on this assumption.

The risk-assessment approach only focused on air contaminants detected in the majority of the prison buildings, including trichloroethylene, tetrachloroethylene, benzene, chloroform, beryllium, cadmium, and mercury. Both 1,3-butadiene and thallium were not included in the risk assessment; 1,3-butadiene was not as widely distributed across the facility as other air contaminants. Furthermore, although 1,3-butadiene has published toxicity information, the half-life in air is extremely short (8 h) as compared to more persistent contaminants such as tetrachloroethylene (3,843 h) and chloroform (6,231 h; Howard 1991). Thallium also was not included in the risk assessment because published inhalation slope factors and reference doses are not available from USEPA.

Two separate receptor populations were evaluated, namely the prison inmate population and the prison staff population. The inmate population was considered to be adult residential, but the workers represent an adult occupational population. It was assumed that both populations were exposed to airborne contaminants primarily through the inhalation pathway.

The air-sampling data were tested for normality using both the Shapiro-Wilk and Kolmogorov-Smirnov tests. The normality tests showed that none of the sampling results for the 7 air contaminants of concern were distributed normally or log-normally. One possible reason the sampling data distributions were skewed (i.e., not normally distributed) was the high percentage of ND values among the sample results. Because the sampling data were neither normally nor log-normally distributed, and the underlying distribution was unknown, a distribution-free approach was used to calculate upper confidence limits for each dataset. The 95% upper confidence limits is considered a reasonable estimate of contaminant exposure point concentrations (USEPA 2002). According to USEPA (2002), the central limit theorem can be used to calculate the 95% upper confidence limits because the approach involves no assumptions regarding the underlying distribution of the dataset (USEPA 2002). The central limit theorem states that, for sufficiently large sample size, the sampling distribution of means (i.e., the sample of sample means) approximately is distributed normally, regardless of the actual underlying distribution of the data (USEPA 2002). The sample sizes for the 7 air contaminants of concern ranged between 60 and 65; ND values in each dataset were replaced by one-half the sample quantitation limit. The 95% upper confidence limits for each air contaminant are summarized in Table 2.

The absorbed dose (D_B) associated with the chemical air concentration (C_a) was calculated for the inhalation exposure pathway using Equation 1,

• ((1))

where B_s is the chemical-specific bioavailability for inhalation, IH is the inhalation rate, ET is the exposure time, and BW is the body weight. The chronic daily intake (CDI), which was used to evaluate potential noncarcinogenic effects, was estimated using Equation 2,

• ((2))

where EF is the exposure frequence, ED is the exposure duration, and AT is the average time. The lifetime average daily absorbed dose or intake (LADD or LADI) was used to evaluate carcinogenic risk, and was calculated using Equation 3.

Table Table 2.. The 95% upper confidence limits (UCLs) for contaminants

Contaminant	Sample size	Concn. range (μg/m^3)	95% UCL (μg/m^3)
^a ND = Not detected.
Trichloroethylene	64	ND^a, 59	16.28
Tetrachloroethylene	64	ND, 160	13.11
Benzene	64	ND, 4.8	2.55
Chloroform	64	ND, 9.3	3.01
Beryllium	65	ND, 0.12	0.04
Cadmium	65	ND, 0.13	0.05
Mercury	65	ND, 1.8	0.68

• ((3))

The slope factors (SF) and reference doses (RfD) used to quantify carcinogenic and noncancer health risks are summarized in Table 3 and were obtained from the USEPA Integrated Risk Information System database (USEPA 2003) and USEPA National Center for Environmental Assessments. Using Equation 4, the product of multiplying the LADD by the SF is the theoretical incremental cancer risk (IELCR) associated with chemical exposure

• ((4))

Using Equation 5, noncarcinogenic risk is calculated by dividing the CDI for each chemical by the chemical-specific RfD. The ratio, which is referred to as the hazard quotient (HQ), determines whether exposure is likely to result in noncarcinogenic adverse health impacts. The hazard index (HI) is an indicator of the likelihood of adverse (noncarcinogenic) health effects occurring due to cumulative chemical exposure, and is obtained by summing the HQs associated with each contaminant of concern. If the HI is less than or equal to a value of 1, then cumulative exposure to different contaminants is not expected to cause adverse health effects.

• ((5))

Risk-assessment results for the worker population

Risk estimates are summarized in Table 4. Figure 1 shows the theoretical cancer risk by chemical assuming average worker exposure conditions. The average, or best estimate, incremental lifetime cancer risk was 1.6 × 10^–5. This indicates that, based on assumed average exposure conditions, the additional risk of cancer attributable to cumulative exposure to the contaminants of concern is approximately 2 in 100,000, which is equivalent to 20 in 1 million. For upperbound, or worst-case, exposure conditions, the estimated incremental lifetime cancer risk was 7.1 × 10^–5, which is equivalent to a population cancer risk of approximately 70 in 1 million. The USEPA (1989) regards cancer risks ranging between 1 in 10 million (i.e., 10^–7) and 100 in 1 million (equivalent to 10^–4) as within the range of acceptable risk. Both the average and worst-case results were within the USEPA (1989) range of acceptable risk.

Table Table 3.. Contaminant toxicity characteristics and target organs^a

Contaminant	SF^bc (mg/kg/d)^–1	RfD^cd (mg/kg/d)^–1	Critical effects for RfD	Target organs
^a Target organs were obtained from National Institute for Occupational Safety and Health Pocket Guide to Chemical Hazards. ^b SF = Inhalation cancer slope factor. ^c Toxicity data sources: I = Integrated Risk Information System; E = U.S. Environmental Protection Agency National Center for Environmental Assessments; R = USEPA Region 3. ^d RFD = Inhalation reference dose. ^e CNS = Central nervous system. ^f CBD = Chronic beryllium disease. ^g PNS = Peripheral nervous system.
Benzene	2.7 × 10^–2 (I)	8.6 × 10^–3 (I)	Decreased lymphocyte count	Eyes, skin, respiratory system blood, CNS^e
Chloroform	8.1 × 10^–2 (I)	1.4 × 10^–2 (E)	Liver cysts	Eyes, skin, liver, kidneys, heart, CNS
Tetrachloroethylene	2.0 × 10^–2 (R)	1.4 × 10^–1 (E)	Hepatoxicity (in mice)	Eyes, skin, respiratory system, liver, kidneys, CNS
Trichloroethylene	4.0 × 10^–1 (E)	1.00 × 10^–2 (E)	Liver, kidneys, fetus development	Eyes, skin, respiratory system, heart, liver, kidneys, CNS
Beryllium	8.4 (I)	5.7 × 10^–6 (I)	CBD^f (lung lesions)	Eyes, skin, respiratory system
Cadmium	6.3 (I)	5.7 × 10^–5 (E)	Proteinuria (kidney impairment)	Respiratory system, kidneys, prostate, blood
Mercury	No Data	8.6 × 10^–5 (I)	Hand tremors, autonomic dysfunction, memory loss	Eyes, skin, CNS, PNS,^g kidneys

Table Table 4.. Summary of risk-assessment results

Risk	Worker HI^a	Worker CR^b	Inmate HI	Inmate CR
^aHI = Hazard index. ^b CR = Cancer risk.
Average estimates	4.5 × 10^–1	1.6 × 10^–5	2.1	1.2 × 10^–4
Worst-case estimates	8.4 × 10^–1	7.1 × 10^–5	3.3	4.0 × 10^–4

Figure 2 shows calculated HI values for each air contaminant assuming average worker exposure conditions. Assuming average exposure conditions, the best estimate HI was 0.45 (Table 4). The upperbound, or worst-case, HI was 0.84. Both results were less than a value of 1, indicating that, even under assumed worst-case exposure conditions, the detected contaminant concentrations in air are lower than the concentrations that would be expected to cause adverse health effects.

Risk-assessment results for the inmate population

Figure 1 shows the theoretical cancer risk by chemical assuming average inmate exposure conditions, and indicates that the main chemical of concern was trichloroethylene. The average, or best estimate, incremental lifetime cancer risk was 1.2 × 10^–4 (i.e., 100 in 1 million), which falls within the USEPA (1989) acceptable risk range. Assuming upperbound, or worst-case, exposure conditions, the incremental lifetime cancer risk was 4.0 × 10^–4 (400 in 1 million), which significantly exceeded the USEPA (1989) acceptable risk range. It is highly unlikely, however, that worst-case exposure conditions would occur at the prison facility.

Figure 2 summarizes the HI by chemical assuming average inmate exposure conditions, and indicates that the main chemicals of concern are mercury and beryllium. The average and worst-case HIs for the inmate population were 2.1 and 3.3, respectively. Inmate population exposure levels for the contaminants of concern exceeded levels that potentially could result in adverse (noncarcinogenic) health impacts. Compared to worker exposure conditions, the single most significant exposure characteristic responsible for the high inmate HI results is the exposure time, that is, the number of hours per day spent indoors at the prison. Table 1 shows that exposure time is the characteristic that varies the most between both populations. The exposure frequency (i.e., number of days per y that a receptor is exposed) also affects the risk assessment results significantly.

Figure Figure 1.. Incremental carcinogenic risk by chemical—average estimates.

DISCUSSION

A methodology has been presented for performing an IAQ evaluation, including assessment of the potential health risks attributable to exposure to indoor air contaminants, at correctional institutions. Ambient indoor and outdoor air was screened for a suite of parameters, including carbon dioxide, carbon monoxide, oxygen, hydrogen sulfide, methane, VOCs, temperature, relative humidity, and lower explosive limit. Indoor and outdoor air was sampled and analyzed for metals, VOCs, SVOCs, and microbial organisms. Surface wipe samples were collected and analyzed for PCBs, SVOCs, and metals. The IAQ investigation included an HVAC system evaluation to assess the HVAC system performance and a building envelope survey to identify potential areas of moisture infiltration.

The health risk assessment consisted of an exposure assessment performed separately for both the worker and inmate populations and based on indoor air–contaminant concentrations detected during the IAQ sampling investigation. The main differences between the worker and inmate population exposure characteristics included the amount of time spent indoors and the number of years spent at the prison facility. Inmates were considered full-time residents for the duration of time incarcerated and expected to spend the majority of time indoors. In contrast, prison workers were assumed to occupy the facility only during an 8- or 10-h work shift. In order to underscore the variability and uncertainty inherent in exposure, the risk-assessment results were presented as average (best estimate) and worst-case risks. The worst-case risk results likely were overestimated, but were presented to provide the theoretical maximum risks that might be attributable to exposure to indoor air contaminants.

The health risk assessment for the worker population yielded theoretical cancer risk and noncancer risk results that fall within limits deemed acceptable by USEPA (1989). For the inmate population, the average, or best estimate, cancer risk fell below 100 in 1 million; however, the HI results and worst-case cancer risk estimates exceeded USEPA (1989) risk limits. Compared to the worker population, the inmate risk results largely are attributed to differences in the amount of time spent indoors at the prison on a daily basis.

Figure Figure 2.. Total hazard index by chemical—average estimates.

Based on the overall IAQ remedial investigation results (indoor air sampling, HVAC system evaluation, and indoor building survey), 2 potential sources for indoor air contamination were identified. The 1st is the presence of subsurface soil and groundwater contamination. Volatile organic compounds and metals, which were the main indoor air contaminants detected, also were found at significant levels during previous site investigations. Soil and groundwater sampling, which was undertaken at the same time as this IAQ investigation, revealed the presence of VOCs in subsurface soil (including tetrachloroethylene), several metals in subsurface soil (including cadmium, mercury, and thallium), and VOCs (including benzene and tetrachloroethylene) in ground-water at concentrations that exceeded New Jersey Department of Environmental Protection environmental criteria. Although the majority of the prison facility is covered by asphalt and concrete building foundations, there still might be sufficient off-gassing of VOCs from soil and migration into building interiors through cracks in the foundation and along utility conduits. Levels of contaminants indoors would be expected to increase at locations where mechanical ventilation is inadequate, which was confirmed in several locations during the HVAC system evaluation. Previous IAQ investigations at the facility also cited the poor condition of the HVAC system. Similarly, the metals detected in indoor air samples and surface wipe samples might be associated with the subsurface soil–metal contamination. The occurrence of metals in indoor air could be attributable to a combination of impaction and settling of supplied ambient air, and earth-moving activities conducted during building construction.

The 2nd potential source for indoor air contamination is the use and storage of chemicals and materials indoors, as well as the habits of building occupants (e.g., smoking and incense burning). Based on a review of the facility's right-to-know information describing chemical substances and other hazards stored on-site, 3 potentially hazardous substances were identified, namely tetrachloroethylene (contained in Dry Molly Lube), 2-phenylphenol (contained in a fungicide, Prestige Herbie I&II), and liquefied petroleum gas. Cleaning agents and chemicals also were identified that could contribute to a deterioration of indoor air quality, given the overall poor air circulation provided by the HVAC system.

CONCLUSION

This paper highlights the vulnerability of prison inmate populations to exposure to indoor air contaminants due to their confinement and extended exposure period, as compared to prison worker populations. Indoor air contamination is of particular concern at prison facilities because inmates necessarily spend the majority of their time indoors, except for brief periods outdoors for recreation or community work. Although indoor air contaminants may be below state or federal National Institute for Occupational Safety and Health and U.S. Occupational Safety and Health Administration recommended workplace exposure levels, the same set of air contaminants deemed acceptable for prison worker populations may pose significant health risks for prison inmates.

According to the New Jersey PEOSH, ensuring an adequate supply of fresh air is considered to be the single most effective method for correcting and preventing IAQ problems. Previous National Institute for Occupational Safety and Health IAQ investigations in office buildings indicate that over 50% of poor IAQ is attributable to poorly functioning HVAC systems (Crandall 1988). An adequate supply of fresh air and good indoor air circulation can minimize or prevent the accumulation of indoor air contaminants to levels that potentially pose health risks. Indoor fresh air circulation can be improved by implementing a preventative maintenance schedule for HVAC systems in accordance with the manufacturer's specifications (or accepted industry practice), and following the American Society of Heating, Refrigerating, and Air-Conditioning Engineers recommendations for fresh air distribution per occupant within the indoor environment.

Periodic (e.g., annual) indoor air screening and sampling/laboratory analysis at correctional institutions would ensure timely detection of airborne contaminants and prevent long-term exposure that might pose health risks, particularly to the inmate population. Periodic testing of soil and water for environmental contamination also would be prudent under applicable conditions.

Acknowledgements

Acknowledgement—The IAQ investigation was funded by the New Jersey Department of Corrections. The opinions or suggestions expressed in this paper are those of the author and do not necessarily reflect the views of the Department. The author acknowledges the contributions of S. Eget, R. Meloskie, and J. Cupriks of The Louis Berger Group in the design and implementation of the indoor air–quality investigation.