Kiyoung Lee

Indoor carbon monoxide and PM2.5 concentrations by cooking fuels in Pakistan

UNLABELLEDnIn developing countries biomass combustion is a frequently used source of domestic energy and may cause indoor air pollution. Carbon monoxide (CO)and particulate matter with an aerodynamic diameter of 2.5 lm or less (PM2.5)were measured in kitchens using wood or natural gas (NG) in a semi-rural community in Pakistan. Daytime CO and PM2.5 levels were measured for eight continuous hours in 51 wood and 44 NG users from December 2005 to April 2006. The laser photometer PM2.5 (Dustrak, TSI) was calibrated for field conditions and PM2.5 measurements were reduced by a factor of 2.77. CO was measured by an electrochemical monitor (Model T15v, Langan). The arithmetic mean for daytime CO concentration was 29.4 ppm in wood users; significantly higher than 7.5 ppm in NG users (P < 0.001). The arithmetic mean for daytime PM2.5 concentrations was 2.74 mg/m3 in wood users; significantly higher than 0.38 mg/m3 in NG users (P < 0.001). Higher peak levels of CO and PM2.5 were also observed in wood users. Time spent in the kitchen during fuel burning was significantly related to increasing CO and PM2.5 concentrations in wood users.These findings suggest that cooking with wood fuel may lead to hazardous concentrations of CO and PM2.5.nnnPRACTICAL IMPLICATIONSnBiomass combustion is frequently used in developing countries for cooking. This study showed very high level of air pollution in kitchens using wood as the cooking fuel. Many people, especially women and children, are vulnerable to exposure to very high levels of air pollutants as they spend time in the kitchen during cooking hours.

Ozone Decay Rates in Residences

In urban and suburban settings, indoor ozone exposures can represent a significant fraction of an individuals total exposure. The decay rate, one of the factors determining indoor ozone concentrations, is inadequately understood in residences. Decay rates were calculated by introducing outdoor air containing 80-160 parts per billion ozone into 43 residences and monitoring the reduction in indoor concentration as a function of time. The mean decay rate measured in the living rooms of 43 Southern California homes was 2.80 + 1.30 hr-1, with an average ozone deposition velocity of 0.049 + 0.017 cm/sec. The experimental protocol was evaluated for precision by repeating measurements in one residence on five different days, collecting 44 same-day replicate measurements, and by simultaneous measurements at two locations in six homes. Measured decay rates were significantly correlated with house type and the number of bedrooms. The observed decay rates were higher in multiple-family homes and homes with fewer than three bedrooms. Homes with higher surface-area-to-volume ratios had higher decay rates. The ratio of indoor-to-outdoor ozone concentrations in homes not using air conditioning and open windows was 68 + 18%, while the ratio of indoor-to-outdoor ozone was less than 10% for the homes with air conditioning in use.

Carbon monoxide and nitrogen dioxide exposures in indoor ice skating rinks

Exposures to carbon monoxide (CO) and nitrogen dioxide (NO2) were determined in seven enclosed ice skating rinks and an outdoor rink. The uptake of CO was also determined by the difference in alveolar CO concentration of the non-smoking hockey players before and after games. Carbon monoxide concentrations in enclosed rinks ranged from 4 to 117 ppm and NO2 concentrations from 342 to 2729 ppb for 2 h hockey games. The CO uptakes were linearly related to the ambient CO concentrations. Alveolar CO of the hockey players increased on average by 0.53 ppm per 1 ppm CO exposure over 2 h. Considering the CO and NO2 levels currently measured in enclosed ice skating rinks, indoor air quality guidelines or standards should be established. It is recommended that 1 h maximum allowable limits of 20 ppm CO and 250 ppb NO2 be established.

Outdoor/Indoor/Personal Ozone Exposures of Children in Nashville, Tennessee

Abstract An ozone (O3) exposure study was conducted in Nashville, TN, using passive O3 samplers to measure six weekly outdoor, indoor, and personal O3 exposure estimates for a group of 10- to 12-yr-old elementary school children. Thirty-six children from two Nashville area communities (Inglewood and Hendersonville) participated in the O3 sampling program, and 99 children provided additional time-activity information by telephone interview. By design, this study coincided with the 1994 Nashville/Middle Tennessee Ozone Study conducted by the Southern Oxidants Study, which provided enhanced continuous ambient O3 monitoring across the Nashville area. Passive sampling estimated weekly average outdoor O3 concentrations from 0.011 to 0.030 ppm in the urban Inglewood community and from 0.015 to 0.042 ppm in suburban Hendersonville. The maximum 1- and 8-hr ambient concentrations encountered at the Hendersonville continuous monitor exceeded the levels of the 1- and 8-hr metrics for the O3 National Ambient Air Quality Standard. Weekly average personal O3 exposures ranged from 0.0013 to 0.0064 ppm (7-31% of outdoor levels). Personal O3 exposures reflected the proportional amount of time spent in indoor and outdoor environments. Air-conditioned homes displayed very low indoor O3 concentrations, and homes using open windows and fans for ventilation displayed much higher concentrations.

Respiratory Protection Against Mycobacterium tuberculosis: Quantitative Fit Test Outcomes for Five Type N95 Filtering-Facepiece Respirators

In preparing to fit test a large workforce, a respirator program manager needs to initially choose respirators that will fit the greatest proportion of employees and achieve the best fits. This article discusses our strategy in selecting respirators from an initial array of seven NIOSH-certified Type N95 filtering-facepiece devices for a respiratory protection program against Mycobacterium tuberculosis (M. tb) aerosol. The seven respirators were screened based on manufacturer-provided fit test data, comfort, and cost. From these 7 devices, 5 were chosen for quantitative fit testing on 40 subjects who were a convenience sample from a cohort of approximately 30,000 workers scheduled to undergo fit testing. Across the five brands, medium/regular-size respirators fit from 8% to 95% of the subjects; providing another size of the same brand improved the pass rates slightly. Gender was not found to significantly affect fit test pass rates for any respirator brand. Among test panel members, an Aearo Corporation respirator (TC 84A-2630) and a 3M Company respirator (TC 84A-0006) provided the highest overall pass rates of 98% and 90%, respectively. We selected these two brands for fit testing in the larger worker cohort. To date, these two respirators have provided overall pass rates of 98% (1793/1830) and 88% (50/57), respectively, which are similar to the test panel results. Among 1850 individuals who have been fit tested, 1843 (99.6%) have been successfully fitted with one or the other brand. In a separate analysis, we used the test panel pass rates to estimate the reduction in M. tb infection risk afforded by the medium/regular-size of five filtering-facepiece respirators. We posed a low-exposure versus a high-exposure scenario for health care workers and assumed that respirators could be assigned without conducting fit testing, as proposed by many hospital infection control practitioners. Among those who would pass versus fail the fit test, we assumed an average respirator penetration (primarily due to faceseal leakage) of .04 and 0.3, respectively. The respirator with the highest overall pass rate (95%) reduced M. tb infection risk by 95%, while the respirator with the lowest pass rate (8%) reduced M. tb infection risk by only 70%. To promote the marketing of respirators that will successfully fit the highest proportion of wearers, and to increase protection for workers who might use respirators without the benefit of being fit tested, we recommend that fit testing be part of the NIOSH certification process for negative-pressure air-purifying respirators with tightly fitting facepieces. At a minimum, we recommend that respirator manufacturers generate and provide pass rate data to assist in selecting candidate respirators. In any event, program managers can initially select candidate respirators by comparing quantitative fit tests for a representative sample of their employee population.

Soil as a Source of Dust and Implications for Human Health

Publisher Summary Soil dust plays a large role in air quality, and dust from soil is the second largest primary particle source after sea salt. Wind and agriculture are two of the primary forces that generate soil dust, although construction, driving on unpaved roads, and other activities may also have an effect. When soil is suspended in the atmosphere as dust, it can be transported and absorbed by the human body. This can result in health problems such as eye irritation, respiratory disorders, pulmonary disease, and an increased risk of lung and skin cancer. People who work in dusty environments, such as agriculture workers, construction workers, and miners are affected the most by soil dust exposure. However, as soil dust increases the amount of particulate matter in the air, it can also influence the health of the general population. This chapter reviews the mechanisms of soil dust generation and exposure, the characteristics of soil dust, and some possible health effects of soil dust exposure. Fine particles pose more of a health risk than larger particles because they can reach the alveolar region of the respiratory system where deposition can cause respiratory damage.

Personal Exposures to Inorganic and Organic Dust in Manual Harvest of California Citrus and Table Grapes

The aim of this study was to determine characteristics of personal exposure to inorganic and organic dust during manual harvest operations of California citrus and table grapes. Personal exposures to inhalable dust and respirable dust were measured five times over a 4-month period of harvesting season. We analyzed components of the dust samples for mineralogy, respirable quartz, endotoxin, and total and culturable microorganisms. Workers manually harvesting were exposed to a complex mixture of inorganic and organic dust. Exposures for citrus harvest had geometric means of 39.7 mg/m3 for inhalable dust and 1.14 mg/m3 for respirable dust. These exposures were significantly higher than those for table grape operations and exceeded the threshold limit value for inhalable dust and respirable quartz. Exposures for table grape operations were lower than the threshold limit value, except inhalable dust exposure during leaf pulling. Considered independently, exposures to inhalable dust and respirable quartz in citrus harvest may be high enough to cause respiratory health effects. The degree of vigorous contact with foliage appeared to be a significant determining factor of exposures in manual harvesting.

Impact of Microenvironmental Nitrogen Dioxide Concentrations on Personal Exposures in Australia

ABSTRACT Indoor and outdoor NO2 concentrations were measured and compared with simultaneously measured personal exposures of 57 office workers in Brisbane, Australia. House characteristics and activity patterns were used to determine the impacts of these factors on personal exposure. Indoor NO2 levels and the presence of a gas range in the home were significantly associated with personal exposure. The time-weighted average of personal exposure was estimated using NO2 measurements in indoor home, indoor workplace, and outdoor home levels. The estimated personal exposures were closely correlated, but they significantly underestimated the measured personal exposures. Multiple regression analysis using other nonmeasured microenvironments indicated the importance of transportation in personal exposure models. The contribution of transportation to the error of prediction of personal exposure was confirmed in the regression analysis using the multinational study database.

Surveillance of indoor air quality in ice skating rinks

Abstract Indoor nitrogen dioxide concentrations in 19 ice skating rinks in the greater. Boston area were monitored for one week each month, over a four-month period. Nitrogen dioxide was selected as an indicator of indoor air quality, and NO2 samples were placed in two locations within each rink. Rinks with higher NO2 levels (in excess of 200 nL/L), under normal operation, in the first monitoring week were mitigated with changes in ventilation system operation in the subsequent months. After the first monitoring period, only two rinks had NO2 levels above 200 nL/L. It was suspected that high levels in these two rinks may have been related to improper ventilation. While high NO2 concentrations were found in the ice skating rinks with propane-powered ice resurfacers, other studies indicate that combustion fuels can also result in elevated indoor concentrations. In order to achieve healthful air quality in indoor ice rinks, it may be necessary to: 1) monitor indoor pollution on a continuous or routine basis; 2) educate rink managers on proper ventilation procedures; and 3) test ventilation systems to ensure that their design and operation are effective.

Interpersonal and daily variability of personal exposures to nitrogen dioxide and sulfur dioxide

Chronic exposure is often assessed using a single measurement per individual or group. However, daily levels of personal exposure can vary greatly. Chronic exposure classification by a single measurement could be significantly affected by the interpersonal and daily variations of exposures. The purpose of this study is to determine the effect of using a single personal exposure measurement on estimating long-term exposure. This study used measurements of consecutive 14 daily personal exposures to nitrogen dioxide (NO2) and sulfur dioxide (SO2) of 50 individuals in Yeochun, Korea. The daily personal exposures were measured by passive samplers. Personal exposure to NO2 was associated with gas cooking, and personal exposure to SO2 was associated with ambient air pollution. Mixed effects models indicated that daily variability was greater than interpersonal variability for both the pollutants. Effectiveness of using single-day personal measurements for long-term population mean exposure was supported by relatively consistent daily population averages, but multiple-day measurements might be warranted for characterizing individual exposures or high-end population exposures such as the 95th percentile. Although classification of high and low exposure groups by 1-day exposure and by 14-day exposure produced similar group totals, 20% of individual NO2 exposures and 31% of individual SO2 exposures were misclassified using 1-day exposures. Average values of 1-day exposure and 14-day exposure were significantly different, but the difference decreased by an increase in the number of measurements for the short-term exposure. The findings were similar for both NO2 and SO2, although the two air pollutants have different sources and behaviors.