Sean Semple

COPD and chronic bronchitis risk of indoor air pollution from solid fuel: a systematic review and meta-analysis

Background Over half the world is exposed daily to the smoke from combustion of solid fuels. Chronic obstructive pulmonary disease (COPD) is one of the main contributors to the global burden of disease and can be caused by biomass smoke exposure. However, studies of biomass exposure and COPD show a wide range of effect sizes. The aim of this systematic review was to quantify the impact of biomass smoke on the development of COPD and define reasons for differences in the reported effect sizes. Methods A systematic review was conducted of studies with sufficient statistical power to calculate the health risk of COPD from the use of solid fuel, which followed standardised criteria for the diagnosis of COPD and which dealt with confounding factors. The results were pooled by fuel type and country to produce summary estimates using a random effects model. Publication bias was also estimated. Results There were positive associations between the use of solid fuels and COPD (OR=2.80, 95% CI 1.85 to 4.0) and chronic bronchitis (OR=2.32, 95% CI 1.92 to 2.80). Pooled estimates for different types of fuel show that exposure to wood smoke while performing domestic work presents a greater risk of development of COPD and chronic bronchitis than other fuels. Conclusion Despite heterogeneity across the selected studies, exposure to solid fuel smoke is consistently associated with COPD and chronic bronchitis. Efforts should be made to reduce exposure to solid fuel by using either cleaner fuel or relatively cleaner technology while performing domestic work.

Respiratory risks from household air pollution in low and middle income countries

A third of the worlds population uses solid fuel derived from plant material (biomass) or coal for cooking, heating, or lighting. These fuels are smoky, often used in an open fire or simple stove with incomplete combustion, and result in a large amount of household air pollution when smoke is poorly vented. Air pollution is the biggest environmental cause of death worldwide, with household air pollution accounting for about 3·5-4 million deaths every year. Women and children living in severe poverty have the greatest exposures to household air pollution. In this Commission, we review evidence for the association between household air pollution and respiratory infections, respiratory tract cancers, and chronic lung diseases. Respiratory infections (comprising both upper and lower respiratory tract infections with viruses, bacteria, and mycobacteria) have all been associated with exposure to household air pollution. Respiratory tract cancers, including both nasopharyngeal cancer and lung cancer, are strongly associated with pollution from coal burning and further data are needed about other solid fuels. Chronic lung diseases, including chronic obstructive pulmonary disease and bronchiectasis in women, are associated with solid fuel use for cooking, and the damaging effects of exposure to household air pollution in early life on lung development are yet to be fully described. We also review appropriate ways to measure exposure to household air pollution, as well as study design issues and potential effective interventions to prevent these disease burdens. Measurement of household air pollution needs individual, rather than fixed in place, monitoring because exposure varies by age, gender, location, and household role. Women and children are particularly susceptible to the toxic effects of pollution and are exposed to the highest concentrations. Interventions should target these high-risk groups and be of sufficient quality to make the air clean. To make clean energy available to all people is the long-term goal, with an intermediate solution being to make available energy that is clean enough to have a health impact.

Secondhand smoke levels in Scottish pubs: the effect of smoke-free legislation

Objective: To compare levels of particulate matter, as a marker of secondhand smoke (SHS) levels, in pubs before and 2 months after the implementation of Scottish legislation to prohibit smoking in substantially enclosed public places. Design: Comparison of SHS levels before and after the legislation in a random selection of 41 pubs in 2 Scottish cities. Methods: Fine particulate matter <2.5 μm in diameter (PM2.5) was measured discreetly for 30 min in each bar on 1 or 2 visits in the 8 weeks preceding the starting date of the Smoking, Health and Social Care (Scotland) Act 2005 and then again 2 months after the ban. Repeat visits were undertaken on the same day of the week and at approximately the same time of the day. Results: PM2.5 levels before the introduction of the legislation averaged 246 μg/m3 (range 8–902 μg/m3). The average level reduced to 20 μg/m3 (range 6–104 μg/m3) in the period after the ban. Levels of SHS were reduced in all 53 post-ban visits, with the average reduction being 86% (range 12–99%). PM2.5 concentrations in most pubs post-ban were comparable to the outside ambient air PM2.5 level. Conclusions: This study has produced the largest dataset of pre- and post-ban SHS levels in pubs of all worldwide smoke-free legislations introduced to date. Our results show that compliance with the Smoking, Health and Social Care (Scotland) Act 2005 has been high and this has led to a marked reduction in SHS concentrations in Scottish pubs, thereby reducing both the occupational exposure of workers in the hospitality sector and that of non-smoking patrons.

Personal exposure monitoring of PM2.5 in indoor and outdoor microenvironments

Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Recent high ambient concentration episodes of air pollutants in European cities highlighted the dynamic nature of human exposure and the gaps in data and knowledge about exposure patterns. In order to support health impact assessment it is essential to develop a better understanding of individual exposure pathways in peoples everyday lives by taking account of all environments in which people spend time. Here we describe the development, validation and results of an exposure method applied in a study conducted in Scotland. A low-cost particle counter based on light-scattering technology - the Dylos 1700 was used. Its performance was validated in comparison with equivalent instruments (TEOM-FDMS) at two national monitoring network sites (R(2)=0.9 at a rural background site, R(2)=0.7 at an urban background site). This validation also provided two functions to convert measured PNCs into calculated particle mass concentrations for direct comparison of concentrations with equivalent monitoring instruments and air quality limit values. This study also used contextual and time-based activity data to define six microenvironments (MEs) to assess everyday exposure of individuals to short-term PM2.5 concentrations. The Dylos was combined with a GPS receiver to track movement and exposure of individuals across the MEs. Seventeen volunteers collected 35 profiles. Profiles may have a different overall duration and structure with respect to times spent in different MEs and activities undertaken. Results indicate that due to the substantial variability across and between MEs, it is essential to measure near-complete exposure pathways to allow for a comprehensive assessment of the exposure risk a person encounters on a daily basis. Taking into account the information gained through personal exposure measurements, this work demonstrates the added value of data generated by the application of low-cost monitors.

Biomass fuel use and indoor air pollution in homes in Malawi.

Background: Air pollution from biomass fuels in Africa is a significant cause of mortality and morbidity both in adults and children. The work describes the nature and quantity of smoke exposure from biomass fuel in Malawian homes. Methods: Markers of indoor air quality were measured in 62 homes (31 rural and 31 urban) over a typical 24 h period. Four different devices were used (one gravimetric device, two photometric devices and a carbon monoxide (HOBO) monitor. Gravimetric samples were analysed for transition metal content. Data on cooking and lighting fuel type together with information on indicators of socioeconomic status were collected by questionnaire. Results: Respirable dust levels in both the urban and rural environment were high with the mean (SD) 24 h average levels being 226 μg/m3 (206 μg/m3). Data from real-time instruments indicated respirable dust concentrations were >250 μg/m3 for >1 h per day in 52% of rural homes and 17% of urban homes. Average carbon monoxide levels were significantly higher in urban compared with rural homes (6.14 ppm vs 1.87 ppm; p<0.001). The transition metal content of the smoke was low, with no significant difference found between urban and rural homes. Conclusions: Indoor air pollution levels in Malawian homes are high. Further investigation is justified because the levels that we have demonstrated are hazardous and are likely to be damaging to health. Interventions should be sought to reduce exposure to concentrations less harmful to health.

The influence of the food environment on overweight and obesity in young children: a systematic review

Background and objective The increasing prevalence of childhood obesity has led to interest in its prevention, particularly through school-based and family-based interventions in the early years. Most evidence reviews, to date, have focused on individual behaviour change rather than the ‘obesogenic environment’. Objective This paper reviews the evidence on the influence of the food environment on overweight and obesity in children up to 8 years. Data sources Electronic databases (including MEDLINE, EMBASE, Cochrane Controlled Trials Register (CCTR), DARE, CINAHL and Psycho-Info) and reference lists of original studies and reviews were searched for all papers published up to 31 August 2011. Study selection Study designs included were either population-based intervention studies or a longitudinal study. Studies were included if the majority of the children studied were under 9 years, if they related to diet and if they focused on prevention rather than treatment in clinical settings. Data extraction Data included in the tables were characteristics of participants, aim, and key outcome results. Quality assessment of the selected studies was carried out to identify potential bias and an evidence ranking exercise carried out to prioritise areas for future public health interventions. Data synthesis Thirty-five studies (twenty-five intervention studies and ten longitudinal studies) were selected for the review. There was moderately strong evidence to support interventions on food promotion, large portion sizes and sugar-sweetened soft drinks. Conclusions Reducing food promotion to young children, increasing the availability of smaller portions and providing alternatives to sugar-sweetened soft drinks should be considered in obesity prevention programmes aimed at younger children. These environment-level interventions would support individual and family-level behaviour change.

Dermal exposure to chemicals in the workplace: just how important is skin absorption?

The study of occupational and environmental exposure to chemicals has traditionally focussed on the quantity of dust, aerosol, or vapour inhaled. This has been driven by the high historic prevalence of respiratory illness among those in mining and manufacturing industries. The large proportion of respiratory physicians working in occupational medicine reflects this. Other exposure routes are often overlooked when evaluating the impact of chemicals on health. It is important to remember that in addition to inhalation, chemicals may enter the body by ingestion, by injection, or by uptake through the unbroken skin (dermal absorption). Often dermal exposure is viewed purely in terms of percutaneous uptake of chemicals. There are however three types of chemical-skin interactions, and an understanding of these is required to characterise the nature of any dermal exposure taking place. Firstly, the chemical may pass through the skin and contribute to the systemic load. Alternatively, the chemical can induce local effects ranging from irritation through to burns or degradation of the barrier properties of the skin. Lastly, the chemical can evoke allergic skin reactions through complex immune system responses that can subsequently trigger responses in the skin at both the point of contact and at skin sites remote to the contact. There is also concern that skin contact may cause respiratory sensitisation. In any given exposure scenario there may be interactions between these modes of action. For example, a chemical can irritate the skin surface leading to increased percutaneous penetration of that, or other, chemicals. However, in each case the substance must diffuse through the outer layers of the skin before any adverse effect is possible. This article aims to highlight the importance of the dermal exposure and absorption route in occupational settings, identify some of the factors that influence exposure and absorption, and describe methods currently used …

REFRESH—reducing families' exposure to secondhand smoke in the home: a feasibility study

Objective To study a novel intervention (REFRESH) aimed at reducing childrens exposure to secondhand smoke (SHS) in their homes. Design A randomised feasibility study. Setting Aberdeen City and Aberdeenshire. Participants A total of 59 smoking mothers with at least one child younger than 6 years. Participation took place between July 2010 and March 2011. Intervention Four home visits over a 1-month period, which involved two 24-h measurements of home air quality (PM2.5) and a motivational interview to encourage changes to smoking behaviour within the home in order to reduce child SHS exposure. The enhanced group received their air quality data as part of their motivational interview at visit 2; the control group received that information at visit 4. Main outcome measures The main outcome measures were comparisons of the data from visits 2 and 4 on the 24-h average concentration of PM2.5, the peak concentration of PM2.5, the percentage of time when household PM2.5 concentrations exceeded a health-based threshold of 35 μg/m3 and childs salivary cotinine (in nanograms per millilitre). The views of the mothers from the enhanced group about their understanding of the intervention and the measures used were also analysed to assess the acceptability and utility of the intervention. Results Of the recruited 54 participants, 48 completed the study: 27 from the control group and 21 from the enhanced group. Both groups experienced reductions in PM2.5 concentrations. When testing paired samples for the enhanced group, there was a significant difference (p<0.05) between visit 2 and visit 4 values for maximum PM2.5 (p=0.006) and for percentage of time over 35 μg/m3 (p=0.017), with average PM2.5 approaching significance (p=0.056). There was no significant difference for salivary cotinine. The qualitative findings showed that mothers were able to understand the data they were shown and were shocked by the values measured in their homes despite being aware of the effects of SHS exposure. They appreciated the intervention taking place in their homes as it allowed them to have personalised data. Many mothers described how they had changed their smoking behaviours in their home and in particular were motivated to protect their own children as a result of the knowledge they had gained. Conclusions Providing mothers who smoke with personalised results about the indoor air quality of their homes along with a motivational interview is feasible and has an effect on improving household air quality. Participants found the intervention understandable and acceptable. Taken overall, the results suggest that a future large-scale trial using measurements of indoor air quality as part of a complex intervention to reduce childrens SHS exposure should be explored.

Reduced lung function due to biomass smoke exposure in young adults in rural Nepal.

This study aimed to assess the effects of biomass smoke exposure on lung function in a Nepalese population, addressing some of the methodological issues seen in previous studies. We carried out a cross-sectional study of adults in a population exposed to biomass smoke and a non-exposed population in Nepal. Questionnaire and lung function data were acquired along with direct measures of indoor and outdoor air quality. Ventilatory function (forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and forced expiratory flow at 25–75% of FVC) was significantly reduced in the population using biomass across all age groups compared to the non-biomass-using population, even in the youngest (16–25 yrs) age group (mean FEV1 (95% CI) 2.65 (2.57–2.73) versus 2.83 (2.74–2.91) L; p=0.004). Airflow obstruction was twice as common among biomass users compared with liquefied petroleum gas users (8.1% versus 3.6%; p<0.001), with similar patterns for males (7.4% versus 3.3%; p=0.022) and females (10.8% versus 3.8%; p<0.001), based on the lower limit of normal. Smoking was a major risk factor for airflow obstruction, but biomass exposure added to the risk. Exposure to biomass smoke is associated with deficits in lung function, an effect that can be detected as early as the late teenage years. Biomass smoke and cigarette smoke have additive adverse effects on airflow obstruction in this setting.

Bar workers' health and environmental tobacco smoke exposure (BHETSE): symptomatic improvement in bar staff following smoke-free legislation in Scotland

Objective: To examine changes in the health of bar workers after smoke-free legislation was introduced. Design: Longitudinal study following bar workers from before legislation introduction, at 2 months after introduction and at 1 year to control for seasonal differences. Setting: Bars across a range of socio-economic settings in Scotland. Participants: 371 bar workers recruited from 72 bars. Intervention: Introduction of smoke-free legislation prohibiting smoking in enclosed public places, including bars. Main outcomes measures: Change in prevalence of self-reported respiratory and sensory symptoms. Results: Of the 191 (51%) workers seen at 1-year follow-up, the percentage reporting any respiratory symptom fell from 69% to 57% (p = 0.02) and for sensory symptoms from 75% to 64% (p = 0.02) following reductions in exposure, effects being greater at 2 months, probably partly due to seasonal effects. Excluding respondents who reported having a cold at either baseline or 1 year, the reduction in respiratory symptoms was similar although greater for “any” sensory symptom (69% falling to 54%, p = 0.011). For non-smokers (n = 57) the reductions in reported symptoms were significant for phlegm production (32% to 14%, p = 0.011) and red/irritated eyes (44% to 18%, p = 0.001). Wheeze (48% to 31%, p = 0.006) and breathlessness (42% to 29%, p = 0.038) improved significantly in smokers. There was no relationship between change in salivary cotinine levels and change in symptoms. Conclusions: Bar workers in Scotland reported significantly fewer respiratory and sensory symptoms 1 year after their working environment became smoke free. As these improvements, controlled for seasonal variations, were seen in both non-smokers and smokers, smoke-free working environments may have potentially important benefits even for smokers.