Effect of PM(10) and O(3) on infant mortality among residents in the Mexico City Metropolitan Area: a case-crossover analysis, 1997-2005

INTRODUCTION

Consistent evidence has shown a positive association between air pollution and daily mortality among adults. Less is known about its effect on infant mortality and the modification of this association by socioeconomic status (SES).

OBJECTIVE

To assess the association of particulate matter with an aerodynamic diameter of ≤10μm (PM(10)) and ozone (O(3)) on infant mortality and its modification by SES.

METHODS

We evaluated the relationship of 24 h mean PM(10) and 1h daily maximum O(3) levels with 12 079 all-cause deaths (3903 respiratory deaths) among 1- to 11-month-old infants residing in the Mexico City Metropolitan Area between January 1997 and December 2005 using a case-crossover approach. The data were analysed using conditional logistic regression models, controlling for weather conditions and day of the week.

RESULTS

Single-effect models showed, for all-cause mortality, increases of 5.5% (95% CI 1% to 10%) at lag1 and 6.6% (2% to 11.4%) at lag2; cumulative exposure models (0-2 days) showed an increase of 6.3% (0.01% to 32.7%). Respiratory mortality increased marginally at 5.3% (-0.02% to 13.2%) with a 1-day lag and 10% (2.1% to 18%) with a 2-day lag per increase of 38.7 μg/m(3) (IQR) in PM(10) levels. When data were stratified by SES (low, medium, and high), only infants with low and medium SES presented a significant increase in risk of all-cause mortality and respiratory mortality in relation to PM(10). O(3) was only significantly related to respiratory mortality in low SES.

CONCLUSION

Our results suggest that in the Mexico City Metropolitan Area, infants with lower SES (low to medium) are at higher risk of mortality when exposed to ambient PM(10) and O(3).

Size fractionate particulate matter, vehicle traffic, and case-specific daily mortality in Barcelona, Spain

Recent epidemiological research suggests that short-term effects of particle matter (PM) in urban areas may preferentially be driven by fine fractions. Questions remain concerning the adversehealth effects of coarse particles generated by noncombustion, traffic-related processes and the mechanism of action of PM. Using a time-stratified case-crossover design, we investigated the association between three independent size fractions, coarse (PM10-2.5), intermodal (PM2.5-1), and very fine PMs (PM1), and three health outcomes, respiratory, cardiovascular, and cerebrovascular mortality in Barcelona, Spain, during the period of March 2003-December 2005. Using existing data, we examined the chemical composition of each fraction to explore the effects of PM from different sources and the mechanisms of action. We found that increased levels of PM, and PM10-2.5 were associated with increased levels of cardiovascular and cerebrovascular mortality at lag 1 and lag 2. At lag 1, the odds ratio (OR) for a 1 microg/m3 increase in PM1 was 1.028 [95% confidence interval (CI), 1.000-1.058] for cardiovascular mortality and 1.063 (95% CI, 1.004-1.124) for cerebrovascular mortality. At lag 1, the odds ratio per a 10 microg/ m3 increase of PM10-2.5 was 1.059 (95% CI, 1.026-1.094) for cardiovascular mortality and 1.098 (95% CI, 1.030-1.171) for cerebrovascular mortality. Association with respiratory mortality was only detected for PM2.5-1 at lag 2 (OR, 1.206 per a 10 microg/ m3 increase; 95% CI, 1.028-1.416). Chemical composition data showed that PM in Barcelona was generated in a large proportion by vehicle traffic. Vehicle traffic PM, generated by combustion and noncombustion processes, should be considered in air pollution mitigation strategies in urban areas.

Climate change and respiratory disease: European Respiratory Society position statement

Climate change will affect individuals with pre-existing respiratory disease, but the extent of the effect remains unclear. The present position statement was developed on behalf of the European Respiratory Society in order to identify areas of concern arising from climate change for individuals with respiratory disease, healthcare workers in the respiratory sector and policy makers. The statement was developed following a 2-day workshop held in Leuven (Belgium) in March 2008. Key areas of concern for the respiratory community arising from climate change are discussed and recommendations made to address gaps in knowledge. The most important recommendation was the development of more accurate predictive models for predicting the impact of climate change on respiratory health. Respiratory healthcare workers also have an advocatory role in persuading governments and the European Union to maintain awareness and appropriate actions with respect to climate change, and these areas are also discussed in the position statement.

Temperature, temperature extremes, and mortality: a study of acclimatisation and effect modification in 50 US cities

OBJECTIVES

The authors examined the increase in mortality associated with hot and cold temperature in different locations, the determinants of the variability in effect estimates, and its implications for adaptation.

METHODS

The authors conducted a case-crossover study in 50 US cities. They used daily mortality and weather data for 6 513 330 deaths occurring during 1989-2000. Exposure was assessed using two approaches. First, the authors determined exposure to extreme temperatures using city-specific indicator variables based on the local temperature distribution. Secondly, they used piecewise linear variables to assess exposure to temperature on a continuous scale above/below a threshold. Effects of hot and cold temperature were examined in season-specific models. In a meta-analysis of the city-specific results, the authors examined several city characteristics as effect modifiers.

RESULTS

Mortality increases associated with both extreme cold (2-day cumulative increase 1.59% (95% CI 0.56 to 2.63)) and extreme heat (5.74% (95% CI 3.38 to 8.15)) were found, the former being especially marked for myocardial infarction and cardiac arrest deaths. The increase in mortality was less marked at less extreme temperatures. The effect of extreme cold (defined as a percentile) was homogeneous across cities with different climates, suggesting that only the unusualness of the cold temperature (and not its absolute value) had a substantial impact on mortality (that is, acclimatisation to cold). Conversely, heat effects were quite heterogeneous, with the largest effects observed in cities with milder summers, less air conditioning and higher population density. Adjustment for ozone led to similar results, but some residual confounding could be present due to other uncontrolled pollutants.

CONCLUSIONS

The authors confirmed in a large sample of cities that both cold and hot temperatures increase mortality risk. These findings suggest that increases in heat-related mortality due to global warming are unlikely to be compensated for by decreases in cold-related mortality and that population acclimatisation to heat is still incomplete.

Short-term respiratory effects of cleaning exposures in female domestic cleaners

Symptoms of obstructive lung disease in domestic cleaners have been related to the use of bleach and other irritant cleaning products. The short-term effects of cleaning exposures on respiratory symptoms and peak expiratory flow (PEF) were investigated in domestic cleaners with respiratory disorders. In a panel study, 43 female domestic cleaners with a recent history of asthma and/or chronic bronchitis completed a 2-week diary, collecting information on respiratory symptoms, PEF and cleaning exposures. Mixed regression models were used to assess daily changes in symptoms and PEF associated with specific cleaning exposures. The probability of having work-related asthma was individually assessed by a computerised diagnostic system and an occupational asthma expert. Lower respiratory tract symptoms were more common on working days and were predominantly associated with exposure to diluted bleach, degreasing sprays/atomisers and air fresheners. Associations with upper respiratory tract symptoms and PEF were less apparent. Eleven (30%) subjects scored positively for work-related asthma. It is concluded that exposure to certain irritant cleaning products aggravates lower respiratory tract symptoms in female domestic cleaners with asthma or chronic bronchitis.

Asthma, chronic bronchitis, and exposure to irritant agents in occupational domestic cleaning: a nested case-control study

BACKGROUND

Women employed in domestic cleaning are at increased risk for symptoms of obstructive lung disease, but the agents responsible are unknown.

AIMS

To investigate common tasks and products in occupational domestic cleaning in relation to respiratory morbidity.

METHODS

Case-control study in domestic cleaning women nested within a large population based survey of women aged 30-65 years; 160 domestic cleaning women with asthma symptoms, chronic bronchitis symptoms, or both and 386 without a history of respiratory symptoms were identified. Detailed exposures were evaluated for 40 cases who reported still having symptoms at the recruitment interview, and 155 controls who reported not having symptoms. All tasks performed and products used when cleaning houses were determined in a face-to-face interview. Lung function, methacholine challenge, and serum IgE testing were performed. Personal exposure measurements of airborne chlorine and ammonia were performed in a subsample. Associations between asthma, chronic bronchitis, and cleaning exposures were evaluated using multiple logistic regression analysis.

RESULTS

Airborne chlorine (median level 0-0.4 ppm) and ammonia (0.6-6.4 ppm) were detectable during occupational domestic cleaning activities. Cases used bleach more frequently than controls; adjusted odds ratio (OR) for intermediate exposure was 3.3 (95% CI 0.9 to 11) and for high exposure 4.9 (1.5 to 15). Other independent associations included accidental inhalation of vapours and gases from cleaning agents and washing dishes. These associations were more pronounced for cases with asthma symptoms than for those with symptoms of chronic bronchitis, but were not related to sensitisation to common allergens.

CONCLUSIONS

Asthma symptoms in domestic cleaning women are associated with exposure to bleach and possibly other irritant agents. The public health impact of the use of irritant cleaning products could be widespread since the use of these products is common both in the workplace and at home.

Asthma symptoms in women employed in domestic cleaning: a community based study

BACKGROUND

Epidemiological studies have shown an association between cleaning work and asthma, but the risk factors are uncertain. The aim of this study was to assess the risk of asthma in women employed in domestic cleaning.

METHODS

A cross sectional study was conducted in 4521 women aged 30 to 65 years. Information on respiratory symptoms and cleaning work history was obtained using a postal questionnaire with telephone follow up. Asthma was defined as reported symptoms in the last year or current use of drugs to treat asthma. Odds ratios (OR) with 95% confidence intervals (CI) for asthma in different cleaning groups were estimated using adjusted unconditional logistic regression models.

RESULTS

593 women (13%) were currently employed in domestic cleaning work. Asthma was more prevalent in this group than in women who had never worked in cleaning (OR 1.46 (95% CI, 1.10 to 1.92)). Former domestic cleaning work was reported by 1170 women (26%), and was strongly associated with asthma (OR 2.09 (1.70 to 2.57)). Current and former non-domestic cleaning work was not significantly associated with asthma. Consistent results were obtained for other respiratory symptoms. Twenty five per cent of the asthma cases in the study population were attributable to domestic cleaning work.

CONCLUSIONS

Employment in domestic cleaning may induce or aggravate asthma. This study suggests that domestic cleaning work has an important public health impact, probably involving not only professional cleaners but also people undertaking cleaning tasks at home.