Average Carbon Monoxide Research Articles

Implications of intense biomass burning over Uttarakhand in April–May 2016

A widespread forest fire episode occurred over Uttarakhand during April 24–May 2, 2016. This event released large amount of carbon monoxide (CO), nitrogen dioxide (NO2) and aerosols in the pristine environment of Uttarakhand. AIRS observations showed 60–125 ppbv higher CO during fire-impacted period with respect to background CO at 925, 850 and 700 hPa. Spatial distribution of CO and fire hotspots over Uttarakhand showed high level of CO over the region of intense biomass burning specifically. Over Dehradun, rate of increase in daily average surface CO was found to be 45 ppbv/day during fire period. Average background and fire-impacted tropospheric column NO2 were found to be 1.7 × 1015 ± 5.0 × 1014 mol/cm2 and 3.0 × 1015 ± 8.5 × 1014 mol/cm2, respectively. Similarly, average background and fire-impacted aerosol optical depth (AOD) were found to be 0.47 ± 0.25 and 0.90 ± 0.35, respectively, for Terra and 0.44 ± 0.17 and 0.86 ± 0.47, respectively, for Aqua observations. Size- and shape-segregated AOD distributions showed enhancement of medium-to-coarse (radius > 0.35 µm) non-spherical particles due to fire episode. CALIPSO height-resolved aerosol subtyping showed dominance of smoke near Uttarakhand up to 10 km altitude. Interspecies correlations indicated the common sources of near-surface CO, CO aloft, AOD and NO2. A relatively poor correlation between near-surface CO and tropospheric column NO2 might be due to chemical transformation of reactive NO2 within the fire plume. Forward trajectories calculated over fire-affected region at 500 m AGL indicated that fire emissions might have influenced the air quality of southern Nepal and northern Uttar Pradesh/Bihar within lower 3 km.

Assessment of indoor air pollutant concentrations and emissions from natural gas cooking burners in residential buildings in Tehran, Iran

The effect of natural gas cooking burner usage on time-dependent concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), and formaldehyde (HCHO) in homes in Tehran was estimated using a mass balance model. The outdoor air concentrations were considered the only background sources of indoor concentrations of CO and NO2, and indoor concentration of HCHO was calculated without considering any background sources. The contributions of the natural gas cooking burner use to the indoor concentrations of CO and NO2 in the residential buildings were significantly affected by season and municipal region and estimated to be 13% (95% uncertainty interval (UI) 8–42) and 26% (15–45), respectively. The annual average indoor concentrations of CO, NO2, and HCHO in the residential buildings were 3431 (2308–6863), 87 (56–169), and 3 (1–20) μg/m3, respectively. Although the average indoor concentrations of all the pollutants were within the permissible range, the upper limits of 95% UI of 24-h average CO and 1-h average NO2 concentrations were higher than the WHO guidelines in 41% and 25% of the cases, respectively. The most efficient measures for control of people’s high exposure to the pollutants from natural gas burners were determined to be partial or total replacement of natural gas burners with electric burners, using the range hood during cooking, reducing frequency and duration of natural gas burner, optimizing ventilation rate, and increasing people awareness about air pollutants emitted by natural gas burners that should be taken with more consideration.

Effects of biodiesel obtained from Canola, sefflower oils and waste oils on the engine performance and exhaust emissions

Biodiesel is a non-toxic, high-cetane, lubricating, biodegradable and renewable alternative diesel engine fuel that contains no sulfur but oxygen in its composition. It can be used in diesel engines in mixed or pure form without any modification. In this study, the effects of using biodiesel consisting of canola, safflower and waste oil mixture obtained by transesterification as well as biodiesel and diesel fuel mixtures of different ratios as a fuel in a four-stroke, single cylinder, air-cooled, direct injection diesel engine, on the engine performance and exhaust emissions were examined. As a result of the experiments suggested that as the biodiesel ratio in the mixture increased, in comparison to diesel fuel, specific fuel consumption and brake thermal efficiency increased as the ratio of BD75 and decreased by 1.95% for BD100. According to results of the emission analysis, the mixture was found to be stable in comparison to diesel fuel, as the average carbon monoxide (CO) amount decreased by 34.28%, hydrocarbon (HC) amount decreased by 17.49%, smoke emission decreased by 50.95% for the given engine load whereas nitric oxide (NOx) increased by 80.50% and carbon dioxide (CO2) increased by 42.62% for the given engine load.

Study on the Annual Reduction Rate of Vehicle Emission Factors for Carbon Monoxide: A Case Study of Urban Road Tunnels in Shenzhen, China

Environmental pollution and energy conservation in urban tunnels have become important issues that affect the scientific design and sustainable development of urban tunnels. The carbon monoxide (CO) concentration in urban road tunnels is regarded as a direct reflection and a useful tracer of the intensity of anthropogenic transportation activities. Previous studies in recent years have paid more attention to pollutant emission factors, but less to the calculation parameters of ventilation design for tunnels. This paper aims to study a reasonable annual reduction rate of CO base emission factors. Therefore, a detailed field measurement was carried out in the four typical urban road tunnels, Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel in Shenzhen, China, from March 29 to September 16, 2014. Measurement results showed that the traffic flow of the four urban tunnels had been approaching the design value, or even beyond the limit. The average daily air velocities in the four tunnels were all within 5 m/s, whereas the maximum air velocity had exceeded the limit of 10 m/s. The CO concentrations in Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel were 17 ppm, 7 ppm, 39 ppm, and 8 ppm, respectively. Moreover, it was found that the average CO emission factors of Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel were 1.075 g/(km·veh), 1.245 g/(km·veh), 4.154 g/(km·veh), and 1.739 g/(km·veh), respectively. Based on the statistical data, the CO emission factors of mixed traffic and passenger cars decrease by an average of 16.4% and 33.3%, respectively, per year through the regression method and by an average of 17.4% and 29.0%, respectively, per year through the extremum method. Finally, when considering the safety factor of 20%, it is more reasonable for the CO base emission to adopt 4% as an annual reduction rate for ventilation design in urban tunnels.

Atmospheric Carbon Dioxide Dynamics over Kazakhstan Derived from Satellite Data

The investigation of atmospheric conditions in the steppe, forest-steppe, and semi-desert zones of Kazakhstan is relevant, the observations of air pollution are carried out in all big settlements. Satellite data are most suitable for solving the problems of quantitative and qualitative assessment of propagation of atmospheric pollutants. The contamination of the atmosphere over large territories which depends on the natural and anthropogenic sources of emission of trace gases can be determined from space. The statistical analysis of ground-based data on the atmospheric concentration of carbon monoxide (CO) over the most polluted big industrial cities is performed. The CO content in the atmosphere over Kazakhstan is analyzed using MOPITT satellite IR radiometer data for the period of 2007–2017. The seasonal and long-term variability of the total CO is revealed. The CO maximum falls on March-April, the minimum is registered in July to October. The average CO content in the atmosphere over Kazakhstan has decreased by 4.7% in the recent decade.

Impact of Ambient Air Pollution and Meteorological Factors on Hospital Admission to the Cardiovascular System Disease on Ulaanbaatar City of Mongolia

Background: Mongolia is situated in northern Central Asia. Landlocked between China and Russia, it is a vast expanse of high attitude grassland steppe, desert, and mountain covering an area of 1,565,000 square kilometers. Air pollution is an increasingly series problem in Mongolia. Materials and Methods: This is a time-series cross over study. All health and air pollution data of 2008-2017 was used for this survey. Results: The mean level of SO2 during the cold season was 35.22 μg/m3 and during the warm season it was 4.65 μg/m3. 24 hours PM10 concentration, during the cold season daily average concentration was 226.77 μg/m3. The 8 hours average daily carbon monoxide concentration (1352.85 μg/m3 [95% CI: 1313.07 - 1396.15]) was high during the cold season, ozone concentration (39.10 μg/m3 [95% CI: 37.95 - 40.35]) was high during the warm season. Air quality depends on metrological parameters. All correlation was statistically significant during the whole year and cold season. In total, 288,832 people get admitted to the hospital due to cardiovascular system disease in Ulaanbaatar during the year of 2008-2017. In general, hospitalization is increasing year by year. Significant associations were found for SO2 with hypertensive diseases (I10 - I15), ischemic heart diseases (I20 - I25), cerebrovascular diseases (I60 - I69), diseases of pulmonary circulation and other forms of heart (I00 - I09, I26 - I52) in all lags. For NO2 was less associated with Ischemic heart diseases (I20 - I25) and diseases of pulmonary circulation and other forms of heart (I00 - I09, I26 - I52). For both PM10 and PM2.5, every disease had observed significant RR in lag 0 - 3. Significant associations were found for air pollutants such as PM10, PM2.5, CO, SO2, and O3 in all lags had a statistically significant association with cold season’s cardiovascular system disease admission. As expected during the warm season significant association was found only lag 1 with PM2.5 and lags (0, 1) CO and O3. Conclusion: As expected this study demonstrated significant correlations between cardiovascular morbidity with PM2.5, PM10, NO2, SO2, CO, O3, and some meteorological parameters.

Enhancement of carbon monoxide removal in an underground car park using ventilation system with single and twin jet fans

This study aims to explore many case scenarios of both single and twin jet fans installation in existing ventilation system such as the operation mode, tilt angle and gap distance of the jet fans on the ventilation efficiency in an underground car park using computational fluid dynamics technique. It was found that the averaged carbon monoxide concentration was 28 ppm after the simulation time of 15 min for conventional ventilation case without jet fans. The inclined single jet fan had lower carbon monoxide concentration than conventional ventilation case. It was found that the straight twin jet fan could remove carbon monoxide gas better than the inclined one. The increasing gap distance increased the carbon monoxide ventilation efficiency of the system. In addition, the energy consumption was analyzed. The inclined single jet fan was potential jet fan installation when considering on both the ventilation efficiency and energy utilization aspects.

Use of Biochar-Producing Gasifier Cookstove Improves Energy Use Efficiency and Indoor Air Quality in Rural Households

Biomass fuels dominate the household energy mix in sub-Saharan Africa. Much of it is used inefficiently in poorly ventilated kitchens resulting in indoor air pollution and consumption of large amounts of wood fuel. Micro-gasification cookstoves can improve fuel use efficiency and reduce indoor air pollution while producing char as a by-product. This study monitored real-time concentrations of carbon monoxide (CO), carbon dioxide (CO2) and fine particulate matter (PM2.5), and amount of firewood used when households were cooking dinner. Twenty-five households used the gasifier cookstove to cook and five repeated the same test with three-stone open fire on a different date. With the gasifier, the average corresponding dinner time CO, CO2, and PM2.5 concentrations were reduced by 57%, 41%, and 79% respectively compared to three-stone open fire. The gasifier had average biomass-to-char conversion efficiency of 16.6%. If the produced char is used as fuel, households could save 32% of fuel compared to use of three-stone open fire and 18% when char is used as biochar, for instance. Adoption of the gasifier can help to reduce the need for firewood collection, hence reducing impacts on the environment while saving on the amount of time and money spent on cooking fuel.

Estimating ground-level CO concentrations across China based on the national monitoring network and MOPITT: potentially overlooked CO hotspots in the Tibetan Plateau

Abstract. Given its relatively long lifetime in the troposphere, carbon monoxide (CO) is commonly employed as a tracer for characterizing airborne pollutant distributions. The present study aims to estimate the spatiotemporal distributions of ground-level CO concentrations across China during 2013–2016. We refined the random-forest–spatiotemporal kriging (RF–STK) model to simulate the daily CO concentrations on a 0.1∘ grid based on the extensive CO monitoring data and the Measurements of Pollution in the Troposphere CO retrievals (MOPITT CO). The RF–STK model alleviated the negative effects of sampling bias and variance heterogeneity on the model training, with cross-validation R2 of 0.51 and 0.71 for predicting the daily and multiyear average CO concentrations, respectively. The national population-weighted average CO concentrations were predicted to be 0.99±0.30 mg m−3 (μ±σ) and showed decreasing trends over all regions of China at a rate of -0.021±0.004 mg m−3 yr−1. The CO pollution was more severe in North China (1.19±0.30 mg m−3), and the predicted patterns were generally consistent with MOPITT CO. The hotspots in the central Tibetan Plateau where the CO concentrations were underestimated by MOPITT CO were apparent in the RF–STK predictions. This comprehensive dataset of ground-level CO concentrations is valuable for air quality management in China.

Characterisation of Indoor PM2.5 and CO concentrations in households using charcoal and wood biomass fuel in Kigali, Rwanda

PDS 72: Environmental health issues in LMIC, Exhibition Hall (PDS), Ground floor, August 28, 2019, 10:30 AM - 12:00 PM Background: Household Air Pollution from biomass cooking with traditional stoves in poorly ventilated households is a major cause of morbidity and mortality in low-income settings worldwide. In Rwanda, about 85% of the population still depend on biomass as the primary source of domestic energy, with wood and charcoal the predominant fuels sources. This study is the first research investigation in urban Rwanda of indoor PM2.5 and CO levels associated with biomass fuel cooking activities. Methods: We conducted a household and cooking activity survey among 40 biomass fuel households in Nyarugenge District, Kigali. In addition we performed air quality monitoring for particulate matter (PM) and carbon monoxide (CO) within those 20 households in which cooking was performed exclusively indoors. Pollutant concentrations were measured at one-minute intervals, using the IQ Air Visual Pro sensor (PM2.5) and electrochemical COA1 (CO) detector adapter devices respectively. Results: Overall, the majority of households (75%) used exclusively charcoal fuel with the remainder using wood and charcoal. In the majority of households (90%) in which monitoring was performed, mean pollutant concentrations were in excess of WHO Air Quality (WHO-AQ) Standards with 24-hour values of 93 µgm-3 and 35.1 ppm for PM2.5 and CO respectively. In those four households where cooking was performed once daily, average CO concentrations were below WHO-AQ Standards. Charcoal fuel was associated with lower average concentrations (CO, PM2.5) compared to those households using a mixture of charcoal and wood fuel (p<0.001). Conclusion: Our findings suggest that household air quality levels associated with charcoal and wood combustion in Kigali, Rwanda exceed WHO AQ standards and are in the hazardous range for human health. Efforts are required to evaluate the impact of household energy policies which facilitate access to cleaner fuel sources and develop effective structural ventilation, educational intervention measures or behavioural change campaigns in this context.

Association of Ambient Air Quality with Hand Grip Strength of Korean Elderly

TPS 732: Neurological effects in adults, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background/Aim: Hand grip strength is an important measure to assess neuromuscular health status of the elderly. We aimed to evaluate the association between ambient air quality and hand grip strength of older population of Korea. Methods: We used nationwide cross-sectional survey data of the elderly living in Korea [i.e., the 2008 National Survey of Korean Elderly]. Maximum hand grip strength (in kilograms) among four measurements was used as an outcome variable. We used nationwide outdoor air quality data of AIRKOREA which can be accessed by the general public. Three-year average values of five pollutants [i.e., PM10 (Particulate Matter), O3 (Ozone), CO (Carbon monoxide), SO2 (sulfur dioxide), NO (nitrogen monoxide)] of each participant’s address were used in the analysis. We included potential effect modifiers such as sex, age, lifestyle, socioeconomic status in the statistical models. Results: We found negative associations between hand grip strength and two air pollutants level (PM10 and CO) in female participants. Each 10μg/m3 increase in three-year average PM10 concentration corresponded to 0.28 kg (95% CI: -0.48, -0.08) lower hand grip strength. Each 100 ppb increase in three-year average CO concentration accord with 0.16 kg (95% CI: -0.25, -0.07) lower hand grip strength. There were no statistically significant association between the rest three pollutants (O3, SO2, NO) and hand grip strength of female participants. We found no significant associations in male participants. Conclusion: This study suggests that poor ambient air quality might be risk factors for decrease of hand grip strength in elderly women, which is an objective component of frailty syndrome. Further works are needed to ascertain this association and understand the mechanisms.

Characterization of M4 carbine rifle emissions with three ammunition types

Muzzle emissions from firing an M4 carbine rifle in a semi-enclosed chamber were characterized for an array of compounds to provide quantitative data for future studies on potential inhalation exposure and rangeland contamination. Air emissions were characterized for particulate matter (PM) size distribution, composition, and morphology; carbon monoxide (CO); carbon dioxide (CO2); energetics; metals; polycyclic aromatic hydrocarbons; and methane. Three types of ammunition were used: a “Legacy” (Vietnam-era) round, the common M855 round (no longer fielded), and its variant, an M855 round with added potassium (K)-based salts to reduce muzzle flash. Average CO concentrations up to 1500 ppm significantly exceeded CO2 concentrations. Emitted particles were in the respirable size range with mass median diameters between 0.33 and 0.58 μm. PM emissions were highest from the M855 salt-added ammunition, likely due to incomplete secondary combustion in the muzzle blast caused by scavenging of combustion radicals by the K salt. Copper (Cu) had the highest emitted metal concentration for all three round formulations, likely originating from the Cu jacket on the bullet. Based on a mass balance analysis of each round's formulation, lead (Pb) was completely emitted for all three round types. This work demonstrated methods for characterizing emissions from gun firing which can distinguish between round-specific effects and can be used to initiate studies of inhalation risk and environmental deposition.

Understanding Spatial Variability of Air Quality in Sydney: Part 1—A Suburban Balcony Case Study

There is increasing awareness in Australia of the health impacts of poor air quality. A common public concern raised at a number of “roadshow” events as part of the federally funded Clean Air and Urban Landscapes Hub (CAUL) project was whether or not the air quality monitoring network around Sydney was sampling air representative of typical suburban settings. In order to investigate this concern, ambient air quality measurements were made on the roof of a two-storey building in the Sydney suburb of Auburn, to simulate a typical suburban balcony site. Measurements were also taken at a busy roadside and these are discussed in a companion paper (Part 2). Measurements made at the balcony site were compared to data from three proximate regulatory air quality monitoring stations: Chullora, Liverpool and Prospect. During the 16-month measurement campaign, observations of carbon monoxide, oxides of nitrogen, ozone and particulate matter less than 2.5-µm diameter at the simulated urban balcony site were comparable to those at the closest permanent air quality stations. Despite the Auburn site experiencing 10% higher average carbon monoxide amounts than any of the permanent air quality monitoring sites, the oxides of nitrogen were within the range of the permanent sites and the pollutants of greatest concern within Sydney (PM2.5 and ozone) were both lowest at Auburn. Similar diurnal and seasonal cycles were observed between all sites, suggesting common pollutant sources and mechanisms. Therefore, it is concluded that the existing air quality network provides a good representation of typical pollution levels at the Auburn “balcony” site.

Prenatal Household Air Pollution Is Associated with Impaired Infant Lung Function with Sex-Specific Effects. Evidence from GRAPHS, a Cluster Randomized Cookstove Intervention Trial.

Approximately 2.8 billion people are exposed daily to household air pollution from polluting cookstoves. The effects of prenatal household air pollution on lung development are unknown. To prospectively examine associations between prenatal household air pollution and infant lung function and pneumonia in rural Ghana. Prenatal household air pollution exposure was indexed by serial maternal carbon monoxide personal exposure measurements. Using linear regression, we examined associations between average prenatal carbon monoxide and infant lung function at age 30 days, first in the entire cohort (n = 384) and then stratified by sex. Quasi-Poisson generalized additive models explored associations between infant lung function and pneumonia. Multivariable linear regression models showed that average prenatal carbon monoxide exposure was associated with reduced time to peak tidal expiratory flow to expiratory time (β = -0.004; P = 0.01), increased respiratory rate (β = 0.28; P = 0.01), and increased minute ventilation (β = 7.21; P = 0.05), considered separately, per 1 ppm increase in average prenatal carbon monoxide. Sex-stratified analyses suggested that girls were particularly vulnerable (time to peak tidal expiratory flow to expiratory time: β = -0.003, P = 0.05; respiratory rate: β = 0.36, P = 0.01; minute ventilation: β = 11.25, P = 0.01; passive respiratory compliance normalized for body weight: β = 0.005, P = 0.01). Increased respiratory rate at age 30 days was associated with increased risk for physician-assessed pneumonia (relative risk, 1.02; 95% confidence interval, 1.00-1.04) and severe pneumonia (relative risk, 1.04; 95% confidence interval, 1.00-1.08) in the first year of life. Increased prenatal household air pollution exposure is associated with impaired infant lung function. Altered infant lung function may increase risk for pneumonia in the first year of life. These findings have implications for future respiratory health. Clinical trial registered with www.clinicaltrials.gov (NCT 01335490).

Air quality impact of carbon monoxide emission from diesel engine electric power generators

AbstractAn emissions inventory and the AERMOD View dispersion model were used to estimate the concentrations and the potential effects of carbon monoxide (CO) from diesel engine electric power generators operated by and providing electricity to a textile factory in Nigeria on its host air shed. The CO emissions from simultaneous operations of all of the electric power generators in the factory resulted in: 1‐hr average CO emissions of 4.2 to 54.5 micrograms per cubic meters (μg/m3) and 24‐hr average CO emissions of 0.3 to 20.9 μg/m3. The estimated 1‐hr averaging period maximum ground‐level concentrations of CO were deposited within the factory, while the 24‐hr maximum ground‐level concentrations are estimated at a distance 90 meters (m) from the factory in a southeast direction. The ground‐level concentrations of CO emanating from the textile factory are within the stipulated ambient air quality standards.

Investigation of exhaust emissions from a stationary diesel engine fuelled with biodiesel

This paper studied the production of waste cooking biodiesel as an alternative fuel for diesel engine. The biodiesel was produced through conventional transesterification process using the base catalyst (KOH). A multi-cylinder diesel engine was used to evaluate the emission of 20% (B20) waste cooking biodiesel fuel at different engine speeds and full load condition. It was found that the characteristics of biodiesel are within the limit of specified standards (American Society for Testing and Materials, ASTM D6751) and comparable to diesel fuel. Engine emission results indicated that waste cooking biodiesel fuel sample reduces the average carbon monoxide (CO) and particulate matter (PM) emissions except nitrogen oxides (NOx) than diesel fuel. Finally, it can be concluded that 20% of waste cooking biodiesel can significantly contribute to lower the harmful emission of an unmodified stationary diesel engine to the environment.

Monitoring and modeling of household air quality related to use of different Cookfuels in Paraguay

In Paraguay, 49% of the population depends on biomass (wood and charcoal) for cooking. Residential biomass burning is a major source of fine particulate matter (PM 2.5) and carbon monoxide (CO) in and around the household environment. In July 2016, cross‐sectional household air pollution sampling was conducted in 80 households in rural Paraguay. Time‐integrated samples (24 hours) of PM 2.5 and continuous CO concentrations were measured in kitchens that used wood, charcoal, liquefied petroleum gas (LPG), or electricity to cook. Qualitative and quantitative household‐level variables were captured using questionnaires. The average PM 2.5 concentration (μg/m3) was higher in kitchens that burned wood (741.7 ± 546.4) and charcoal (107.0 ± 68.6) than in kitchens where LPG (52.3 ± 18.9) or electricity (52.0 ± 14.8) was used. Likewise, the average CO concentration (ppm) was higher in kitchens that used wood (19.4 ± 12.6) and charcoal (7.6 ± 6.5) than in those that used LPG (0.5 ± 0.6) or electricity (0.4 ± 0.6). Multivariable linear regression was conducted to generate predictive models for indoor PM 2.5 and CO concentrations (predicted R 2 = 0.837 and 0.822, respectively). This study provides baseline indoor air quality data for Paraguay and presents a multivariate statistical approach that could be used in future research and intervention programs.

Assessment of carbon monoxide exposure in roadside food-vending shanties using coal cookstoves in Kolkata, India

Roadside food-vending shanties using coal cookstoves may be an important source of carbon monoxide (CO) exposure in megacities in India. The shanties are often small, congested and poorly ventilated, and very little is known about the level of human exposure to CO. Here, we assessed the level of exposure to CO in 25 roadside food-vending shanties using coal cookstoves in Kolkata, India. Portable electrochemical CO monitors were used to measure CO concentrations during peak and non-peak customer-periods in closed (blocked from three sides) and semi-closed (blocked from two sides) shanties. Measurements were taken where customers sit indoor about 5–7 ft away from the cookstoves. The shanties' ventilation rates were measured using tracer gas concentration-decay technique. Levels of blood carboxyhaemoglobin (COHb) and exhaled CO were estimated using regression models. The 1-hr time weighted average (TWA) indoor CO exposure levels ranged from 7.8 to 18.1 ppm during peak-periods, and 0.7–3.1 ppm during non-peak-periods. The exposure levels during peak-periods exceeded the USEPA's reference limit of 9 ppm in all cases in the closed shanties, and in 71% of cases in the semi-closed shanties. The ventilation rates ranged from 5.5 to 23.4 and 14.8 to 32.5 cubic feet per minute (cfm) per person for the closed and semi-closed shanties, respectively, indicating poor ventilation in some shanties. There was significant variation (p = 0.01) in the level of indoor CO exposure between peak and non-peak periods, and between shanty types. The estimated levels of blood COHb during peak and non-peak hours were 0.78 ± 0.7% and 0.35 ± 0.07%, respectively, that were within the normal physiological values in non-smokers.

Determinants of commuter exposure to PM2.5 and CO during long-haul journeys on national highways in India

National Highways (NH) are the major road networks linking cities but exposure studies during long commutes on highways are limited. We assessed exposure concentrations of fine particles ≤2.5 μm in diameter (PM2.5) and carbon monoxide (CO) inside bus, ac (air-conditioned) and non-ac car and on an Indian NH over 200 km length. A total of nine round journeys were made in three modes. Analysis of variance (ANOVA) and generalized linear model (GLM) were applied to quantify the contribution of determinants that may explain the variability of exposure concentrations and their association with in-vehicle temperature and relative humidity (RH). The highest and lowest exposures concentrations to PM2.5 were observed in non-ac car (89 ± 32 μg m−3) and the ac car (55 ± 19 μg m−3). Exposures concentrations in non-ac car were higher during in-city travel (113 ± 36 μg m−3). The average CO exposure concentrations were highest in ac car (2.0 ± 0.9 ppm). Results of GLM analysis suggested that travel mode, highway segments (in/out-city) and the journey times are key determinants of personal exposure concentrations. Travel mode for PM2.5 (15%) and NH segments for CO (21%) explained maximum variability. Altogether, these explained 33% and 57% of the variability in PM2.5 and CO exposure concentrations, respectively. PM2.5 consists of soot, mineral and fly ash that are a proxy of fresh exhaust emissions, re-suspended road dust and industrial emissions, respectively. Additionally, EDX analyses revealed an abundance of Si, Al, Ca and Pb, confirming re-suspension, brake/tire wear and construction dust as important sources.

Trends in passenger exposure to carbon monoxide inside a vehicle on an arterial highway of the San Francisco Peninsula over 30 years: A longitudinal study

ABSTRACTThis paper describes a long-term trend study of passenger exposure to carbon monoxide (CO) inside a vehicle traveling on an arterial highway in northern California. CO exposure was measured during four field surveys on State Route #82 (El Camino Real) on the San Francisco Peninsula in 1980–1981, 1991–1992, 2001–2002, and 2010–2011. Each field survey took at least 12 months. Fifty trips from each survey—for a total of 200 trips—were matched by date, day of the week, and starting time of the day to facilitate comparisons over three decades. The mean net CO concentration of each trip was obtained by subtracting the background CO level from the average CO concentration for the entire trip. The mean net CO concentration (0.5 ppm) for 2010–2011 was only 5.2% of that (9.7 ppm) for 1980–1981. For the 50 trips, the average travel time for the 1980–1981 period (39.6 min) was only 8.3% higher than during the 2010–2011 period (36.3 min). The estimated round-trip distance on the highway was held constant at 11.8 miles. The reduction in the mean net CO concentration was attributed to more stringent CO emission standards on new vehicles sold in California since 1980. The state’s cold-temperature CO standard implemented in 1996 appeared to reduce high CO concentrations that were observed during the late fall and winter of 1980–1981. In addition, the observed standard deviation in concentration fell from 3.1 ppm in 1980–1981 to 0.2 ppm in 2010–2011, and the range of the 50 mean net CO concentrations narrowed from 14.9 ppm in 1980–1981 to 1.1 ppm in 2010–2011, but the relative variability, as indicated by the geometric standard deviation, remained the same. These results have important scientific implications for regulatory policies designed to control air pollution from motor vehicles.Implications: Many developing countries launched or expanded their mobile source emission control programs in the 1990s, yet many of them do not have adequate inspection and maintenance (I/M) programs. The El Camino Real study shows the long-term public health benefits of more stringent motor vehicle emission standards for carbon monoxide (CO) on new cars and of an I/M program (Smog Check) on the existing fleet in California. The study provides a protocol for conducting standardized field surveys of in-vehicle exposure on a periodic basis. Such surveys would enable developing countries to assess the progress of their mobile source emission control programs.