Simulation of working population exposures to carbon monoxide using EXPOLIS-Milan microenvironment concentration and time-activity data

Air pollution may affect the assessment of smoking habits by exhaled carbon monoxide measurements

BACKGROUND

While European air quality policies reduce ambient carbon monoxide (CO) concentrations in general, there are still areas affected by high environmental CO exposure from transportation, industry and burning low-quality fossil fuels. We investigated, how these CO amounts might influence exhaled CO measurements used to monitor the smoking status of healthy subjects.

METHODS

A cross-sectional study of healthy adults living in areas of high air pollution (N = 742) and low air pollution (N = 197) in Poland. They completed a survey regarding their smoking habits and underwent necessary body measurements including exhaled CO concentration levels.

RESULTS

Ambient CO levels were much higher in highly pollutes cities. Also exhaled CO levels in subjects from high pollution areas were significantly higher, independent of subject smoking status (8.25 ppm vs. 3.26 ppm). Smokers exhaled more CO than non-smokers. Although the duration of smoking did not affect the CO levels, they were proportional to the number of cigarettes smoked during the day, especially for higher amounts of cigarettes and in unpolluted areas. It was possible to differentiate active from passive smokers in all areas, but the difference for passive smokers vs. non-smokers was significant only in low pollution city inhabitants.

CONCLUSIONS

Exhaled CO levels were confirmed to be a good indicator of smoking status and smoking pattern in healthy subjects. However, high environmental CO levels both increase baseline exhaled CO concentrations in non-smokers affecting their discrimination from passive smokers, and obscure categorizing cigarette consumption in heavy smokers. These findings add important evidence on both understanding of exhaled CO monitoring results and a significance of environmental CO exposure in areas with high pollution.

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.

Airborne particulate matter and gaseous air pollutants in residential structures in Lodi province, Italy

The province of Lodi is located in northern Italy on the Po River plain, where high background levels of air pollutants are prevalent. Lodi province is characterized by intensive agriculture, notably animal husbandry. This paper assesses indoor levels of selected airborne pollutants in 60 homes in the province, with special attention to size-fractionated particulate matter (PM). Indoor PM₂.₅ concentrations are frequently higher than current guidelines. PM₁₀ and nitrogen dioxide also exceed the respective guideline recommendations in some cases, noting that 24-h nitrogen dioxide levels were compared with an annual limit value. All other studied pollutant levels are below current international guidelines. Among indoor PM size fractions, PM₀.₅ is predominant in terms of mass concentrations corresponding to 57% of PM₁₀ in summer and 71% in winter. A strong seasonal trend is observed for all studied pollutants, with higher levels in winter corresponding to changes in ambient concentrations. The seasonal variation in PM₁₀ is largely due to PM₀.₅ increase from summer to winter. Summer indoor PM levels are mainly from indoor-generated particles, while particles of outdoor origin represent the main contribution to winter indoor PM levels. On average, indoor concentrations of coarse PM are mostly constituted by indoor-generated particles.

PRACTICAL IMPLICATIONS

This study presents a comparison between measured indoor concentrations in the study area and indoor air quality guideline criteria. Accordingly, particulate matter (PM) and NO₂ are identified as key pollutants that may pose health concerns. It is also found that indoor PM in residential units is mainly constituted by particles with aerodynamic diameters <0.5 μm, especially in winter. Risk mitigation strategies should be focused on the reduction in indoor levels of NO₂ and ultrafine and fine particles, both infiltrated from outdoors and generated by indoor sources.

Determinants of residential indoor and transportation activity times in Korea

Information on time spent in microenvironments has a critical role for personal exposure to environmental pollutants. Unlike several large-scale studies in Western countries, no comprehensive research on time-activity patterns for exposure assessment has been conducted in Korea. We investigated determinants of residential indoor and transportation times of individuals over 10-years old in the Korean population. The population-based study collected time-activity patterns of 31,634 Koreans for two consecutive days. The residential indoor and transportation times were collected for a weekday and a weekend day. The impact of sociodemographic factors on time-activity was assessed using multiple linear regression models. The residential indoor times were 14.23 h for the weekday and 16.13 h for the weekend and shorter than those in Western countries. The transportation times were 1.75 h for the weekday and 1.68 h for the weekend day. The most significant factors in residential indoor time were employment status, age, monthly income, and gender for the weekday and employment status and gender for the weekend day. The factors in transportation were gender, employment status, and monthly income for the weekday and gender, employment status, age, and marriage status for the weekend day. Determinants of the time-activity pattern need to be taken into account in exposure assessment, epidemiological analyses, and exposure simulations, as well as in the development of preventive strategies. As Korean population activity patterns are substantially different from those in Western countries such as USA, Germany, and UK, this information could be critical for exposure assessment in Korea and other Asian countries.

Factors affecting exhaled carbon monoxide levels in coffeehouses in the Western Black Sea region of Turkey

The aim of this study was to evaluate indoor air quality and factors affecting expired carbon monoxide (CO) levels in a coffeehouse environment. This cross-sectional study was conducted at 16 randomly selected coffeehouses in Duzce, Turkey, during November 2007 to March 2008. A total of 547 people, average age 46.72 ± 17.03 (19—82) years, participated. The selected coffeehouses were divided into four groups: (1) smoking, (2) nonsmoking, (3) old-style and (iv) new-style coffeehouses. Prior to entering the coffeehouse, exhaled CO levels in smokers (mean 21.17 ± 6.73 parts per million [ppm]) were significantly higher than those for nonsmokers (6.51 ± 4.56 ppm; p < 0.001). Measurements taken after 2 hours in the coffeehouse also showed significantly higher CO concentrations for smokers (22.72 ± 5.31 ppm), compared to nonsmokers (6.51 ± 4.56 ppm; p < 0.001). It was determined that CO levels inside coffee shops were above the WHO guidelines. Exhaled CO levels in nonsmokers are influenced by the ambient CO levels as a result of the use of cigarettes in coffeehouses in addition to the structure of coffeehouses.

Personal exposure of traffic police officers to particulate matter, carbon monoxide, and benzene in the city of Milan, Italy

The aim of this work was to quantify the personal exposure of traffic police officers to particulate matter (PM), carbon monoxide (CO), benzene, toluene, ethylbenzene, and xylenes. The contributions of some behavioral, occupational, and meteorological determinants of exposure also were evaluated. Personal exposure to airborne contaminants was measured on 130 selected volunteers in four seasonal sampling sessions. CO was measured with high sampling frequency. A time-activity diary was completed by traffic police officers during their work shift. Mean (median) personal exposure levels of carbon monoxide, respirable particles (PM(resp)), and benzene were 3.51 (3.22) mg/m(3), 128 (115) microg/m(3) and 11.5 (9.6) microg/m(3), respectively. The highest ambient mean levels of PM(resp), CO, and benzene were found during cold seasons. Measurements taken where traffic is directed, schools are guarded, and other outdoor tasks are performed showed the highest median CO concentrations. As expected, wind decreased exposure to CO and benzene. Exposure was not significantly affected by active tobacco smoke. A key finding was that airborne concentrations determined by fixed measurement stations reported in other studies greatly underestimated traffic officers' exposure to airborne contaminants. The proximity to an emission source determined by the occupational activity was the factor that most affected exposure. For this reason, fixed stations are poor predictors of roadside exposures to airborne pollutants.

Spatial variations in estimated chronic exposure to traffic-related air pollution in working populations: a simulation

Background

Chronic exposure to traffic-related air pollution is associated with a variety of health impacts in adults and recent studies show that exposure varies spatially, with some residents in a community more exposed than others. A spatial exposure simulation model (SESM) which incorporates six microenvironments (home indoor, work indoor, other indoor, outdoor, in-vehicle to work and in-vehicle other) is described and used to explore spatial variability in estimates of exposure to traffic-related nitrogen dioxide (not including indoor sources) for working people. The study models spatial variability in estimated exposure aggregated at the census tracts level for 382 census tracts in the Greater Vancouver Regional District of British Columbia, Canada. Summary statistics relating to the distributions of the estimated exposures are compared visually through mapping. Observed variations are explored through analyses of model inputs.

Results

Two sources of spatial variability in exposure to traffic-related nitrogen dioxide were identified. Median estimates of total exposure ranged from 8 μg/m³ to 35 μg/m³ of annual average hourly NO₂ for workers in different census tracts in the study area. Exposure estimates are highest where ambient pollution levels are highest. This reflects the regional gradient of pollution in the study area and the relatively high percentage of time spent at home locations. However, for workers within the same census tract, variations were observed in the partial exposure estimates associated with time spent outside the residential census tract. Simulation modeling shows that some workers may have exposures 1.3 times higher than other workers residing in the same census tract because of time spent away from the residential census tract, and that time spent in work census tracts contributes most to the differences in exposure. Exposure estimates associated with the activity of commuting by vehicle to work were negligible, based on the relatively short amount of time spent in this microenvironment compared to other locations. We recognize that this may not be the case for pollutants other than NO_2. These results represent the first time spatially disaggregated variations in exposure to traffic-related air pollution within a community have been estimated and reported.

Conclusion

The results suggest that while time spent in the home indoor microenvironment contributes most to between-census tract variation in estimates of annual average exposures to traffic-related NO₂, time spent in the work indoor microenvironment contributes most to within-census tract variation, and time spent in transit by vehicle makes a negligible contribution. The SESM has potential as a policy evaluation tool, given input data that reflect changes in pollution levels or work flow patterns due to traffic demand management and land use development policy.

Characterisation of urban inhalation exposures to benzene, formaldehyde and acetaldehyde in the European Union: comparison of measured and modelled exposure data

BACKGROUND, AIM AND SCOPE

All across Europe, people live and work in indoor environments. On average, people spend around 90% of their time indoors (homes, workplaces, cars and public transport means, etc.) and are exposed to a complex mixture of pollutants at concentration levels that are often several times higher than outdoors. These pollutants are emitted by different sources indoors and outdoors and include volatile organic compounds (VOCs), carbonyls (aldehydes and ketones) and other chemical substances often adsorbed on particles. Moreover, legal obligations opposed by legislations, such as the European Union's General Product Safety Directive (GPSD) and Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), increasingly require detailed understanding of where and how chemical substances are used throughout their life-cycle and require better characterisation of their emissions and exposure. This information is essential to be able to control emissions from sources aiming at a reduction of adverse health effects. Scientifically sound human risk assessment procedures based on qualitative and quantitative human exposure information allows a better characterisation of population exposures to chemical substances. In this context, the current paper compares inhalation exposures to three health-based EU priority substances, i.e. benzene, formaldehyde and acetaldehyde.

MATERIALS AND METHODS

Distributions of urban population inhalation exposures, indoor and outdoor concentrations were created on the basis of measured AIRMEX data in 12 European cities and compared to results from existing European population exposure studies published within the scientific literature. By pooling all EU city personal exposure, indoor and outdoor concentration means, representative EU city cumulative frequency distributions were created. Population exposures were modelled with a microenvironment model using the time spent and concentrations in four microenvironments, i.e. indoors at home and at work, outdoors at work and in transit, as input parameters. Pooled EU city inhalation exposures were compared to modelled population exposures. The contributions of these microenvironments to the total daily inhalation exposure of formaldehyde, benzene and acetaldehyde were estimated. Inhalation exposures were compared to the EU annual ambient benzene air quality guideline (5 microg/m3-to be met by 2010) and the recommended (based on the INDEX project) 30-min average formaldehyde limit value (30 microg/m3).

RESULTS

Indoor inhalation exposure contributions are much higher compared to the outdoor or in-transit microenvironment contributions, accounting for almost 99% in the case of formaldehyde. The highest in-transit exposure contribution was found for benzene; 29.4% of the total inhalation exposure contribution. Comparing the pooled AIRMEX EU city inhalation exposures with the modelled exposures, benzene, formaldehyde and acetaldehyde exposures are 5.1, 17.3 and 11.8 microg/m3 vs. 5.1, 20.1 and 10.2 microg/m3, respectively. Together with the fact that a dominating fraction of time is spent indoors (>90%), the total inhalation exposure is mostly driven by the time spent indoors.

DISCUSSION

The approach used in this paper faced three challenges concerning exposure and time-activity data, comparability and scarce or missing in-transit data inducing careful interpretation of the results. The results obtained by AIRMEX underline that many European urban populations are still exposed to elevated levels of benzene and formaldehyde in the inhaled air. It is still likely that the annual ambient benzene air quality guideline of 5 microg/m3 in the EU and recommended formaldehyde 30-min average limit value of 30 microg/m3 are exceeded by a substantial part of populations living in urban areas. Considering multimedia and multi-pathway exposure to acetaldehyde, the biggest exposure contribution was found to be related to dietary behaviour rather than to inhalation.

CONCLUSIONS

In the present study, inhalation exposures of urban populations were assessed on the basis of novel and existing exposure data. The indoor residential microenvironment contributed most to the total daily urban population inhalation exposure. The results presented in this paper suggest that a significant part of the populations living in European cities exceed the annual ambient benzene air quality guideline of 5 microg/m3 in the EU and recommended (INDEX project) formaldehyde 30-min average limit value of 30 microg/m3.

RECOMMENDATIONS AND PERSPECTIVES

To reduce exposures and consequent health effects, adequate measures must be taken to diminish emissions from sources such as materials and products that especially emit benzene and formaldehyde in indoor air. In parallel, measures can be taken aiming at reducing the outdoor pollution contribution indoors. Besides emission reduction, mechanisms to effectively monitor and manage the indoor air quality should be established. These mechanisms could be developed by setting up appropriate EU indoor air guidelines.