Nitrogen dioxide and mortality: review and meta-analysis of long-term studies.

Exposure to ambient nitrogen dioxide (NO2) has been linked to increased mortality in several epidemiological studies but the question remains of whether NO2 is directly responsible for the health effects or is only an indicator of other pollutants, including particulate matter. The aim of the present review was to provide pooled estimates of the long-term effects of NO2 on mortality, which are potentially useful for health impact assessment. We selected 23 papers, published from 2004 to 2013, evaluating the relationship between NO2 and mortality, also including an assessment of the effect of particulate matter exposure. A random-effects meta-analysis was carried out on 19 studies. The pooled effect on mortality was 1.04 (95% CI 1.02-1.06) with an increase of 10 µg · m(-3) in the annual NO2 concentration and 1.05 (95% CI 1.01-1.09) for particulate matter <2.5 µm in diameter (PM2.5) (10 µg · m(-3)). The effect on cardiovascular mortality was 1.13 (95% CI 1.09-1.18) for NO2 and 1.20 (95% CI 1.09-1.31) for PM2.5. The NO2 effect on respiratory mortality was 1.03 (95% CI 1.02-1.03) and 1.05 (95% CI 1.01-1.09) for PM2.5. Four bipollutant analyses with particulate matter and NO2 in the same models showed minimal changes in the effect estimates of NO2. There is evidence of a long-term effect of NO2 on mortality as great as that of PM2.5. An independent effect of NO2 emerged from multipollutant models.

Long-term exposure to traffic-related PM(10) and decreased heart rate variability: is the association restricted to subjects taking ACE inhibitors?

BACKGROUND: Alterations in heart rate variability (HRV) are a potential link between exposure to traffic-related air pollution and cardiovascular mortality. OBJECTIVES: We investigated whether long-term exposure to traffic-related PM(10) (TPM(10)) is associated with HRV in older subjects and/or in participants taking specific cardiovascular treatment or with self-reported heart disease. METHODS: We included 1607 subjects from the general population aged 50 to 72 years. These participants from the SAPALDIA cohort underwent ambulatory 24-hr electrocardiogram monitoring. Associations of average annual exposure to TPM(10) over 10 years with HRV parameters from time and frequency domains were estimated using multivariable mixed linear models. Effect estimates are expressed as percent changes in geometric means. RESULTS: HRV was only associated with TPM(10) in participants under ACE inhibitor therapy (N=94). A 1 µg/m(3) increment, approximately equivalent to an interquartile range, in 10 year average TPM(10) was associated with decrements of 14.5% (95% confidence interval (CI), -25.9 to -1.3) in high frequency (HF) power, of 4.5% (-8.2 to -0.5) in the standard deviation of all normal-to-normal RR intervals (SDNN), of 10.6% (-18.5 to -1.9) in total power (TP) and an increase of 9.2% (0.8 to 20.2) in the LF/HF power ratio. CONCLUSIONS: In the absence of an overall effect our results suggest that alterations in HRV, a measure of autonomic control of the cardiac rhythm, may not be a central mechanism by which long-term exposure to TPM(10) increases cardiovascular mortality. Novel evidence on an effect in persons under ACE inhibitor treatment needs to be confirmed in future studies.

The Year of the Lung: outdoor air pollution and lung health.

With reference to the Year of the Lung, current knowledge of the respiratory effects of current ambient air pollution is reviewed. Acute respiratory effects are well established. Studies such as SAPALDIA and others now shed light on the long-term effects on chronic pathologies and on the health benefit of air quality improvements. The identification of those at highest risk and of local effects of not yet regulated traffic-related pollutants remains a research priority.

Improvements in PM10 exposure and reduced rates of respiratory symptoms in a cohort of Swiss adults (SAPALDIA).

RATIONALE: Reductions in mortality following improvements in air quality were documented by several studies, and our group found, in an earlier analysis, that decreasing particulate levels attenuate lung function decline in adults. OBJECTIVES: We investigated whether decreases in particulates with an aerodynamic diameter of less than 10 microm (PM10) were associated with lower rates of reporting respiratory symptoms (i.e., decreased morbidity) on follow-up. METHODS: The present analysis includes 7,019 subjects who underwent detailed baseline examinations in 1991 and a follow-up interview in 2002. Each subject was assigned model-based estimates of average PM10 during the 12 months preceding each health assessment and the difference was used as the exposure variable of interest (DeltaPM10). Analyses were stratified by symptom status at baseline and associations between DeltaPM10 and change in symptom status during follow-up were adjusted for important baseline characteristics, smoking status at follow-up, and season. We then estimated adjusted odds ratios for symptoms at follow-up and numbers of symptomatic cases prevented due to the observed reductions in PM10. MEASUREMENTS AND MAIN RESULTS: Residential exposure to PM10 was lower in 2002 than in 1991 (mean decline 6.2 microg/m3; SD = 3.9 microg/m3). Estimated benefits (per 10,000 persons) attributable to the observed changes in PM10-levels were: 259 (95% confidence interval [CI]: 102-416) fewer subjects with regular cough, 179 (95% CI, 30-328) fewer subjects with chronic cough or phlegm and 137 (95% CI, 9-266) fewer subjects with wheezing and breathlessness. CONCLUSIONS: Reductions in particle levels in Switzerland over the 11-year follow-up period had a beneficial effect on respiratory symptoms among adults.

Magnetic field exposure and neurodegenerative diseases--recent epidemiological studies.

OBJECTIVES: To analyse the results of recent studies not yet included in a 2003 report of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) on occupational exposure to low-frequency electromagnetic fields as potential risk factor for neurodegenerative diseases. METHODS: A literature search was conducted in the online databases of PubMed, ISI Web of Knowledge, DIMDI and COCHRANE, as well as in specialised databases and journals. Eight studies published between January 2000 and July 2005 were included in the review. RESULTS: The findings of these studies contribute to the evidence of an association between occupational magnetic field exposure and the risk of dementia. Regarding amyotrophic lateral sclerosis, the recent results confirm earlier observations of an association with electric and electronic work and welding. Its relationship with magnetic field exposure remains unsolved. There are only few findings pointing towards an association between magnetic field exposure and Parkinson's disease. CONCLUSIONS: The epidemiological evidence for an association between occupational exposure to low-frequency electromagnetic fields and the risk of dementia has increased during the last five years. The impact of potential confounders should be evaluated in further studies.

Living near main streets and respiratory symptoms in adults: the Swiss Cohort Study on Air Pollution and Lung Diseases in Adults.

The Swiss Cohort Study on Air Pollution and Lung Diseases in Adults (SAPALDIA), conducted in 1991 (SAPALDIA 1) in eight areas among 9,651 randomly selected adults aged 18-60 years, reported associations among the prevalence of respiratory symptoms, nitrogen dioxide, and particles with an aerodynamic diameter of less than 10 microg/m3. Later, 8,047 subjects reenrolled in 2002 (SAPALDIA 2). The effects of individually assigned traffic exposures on reported respiratory symptoms were estimated, while controlling for socioeconomic and exposure- and health-related factors. The risk of attacks of breathlessness increased for all subjects by 13% (95% confidence interval: 3, 24) per 500-m increment in the length of main street segments within 200 m of the home and decreased in never smokers by 12% (95% confidence interval: 0, 22) per 100-m increment in distance from home to a main street. Living within 20 m of a main street increased the risks of regular phlegm by 15% (95% confidence interval: 0, 31) and wheezing with breathing problems by 34% (95% confidence interval: 0, 79) in never smokers. In 2002, the effects related to road distance were different from those in 1991, which could be due to changes in the traffic pollution mixture. These findings among a general population provide strong confirmation that living near busy streets leads to adverse respiratory health effects.

The German view: effects of nitrogen dioxide on human health--derivation of health-related short-term and long-term values.

The presented overview concerning health relevant effects caused by nitrogen dioxide (NO2) resumes the current state of results from animal experiments and human studies (epidemiology and short-term chambers studies). NO2 concentrations applied in animal experiments were mostly considerably higher than in ambient air. Therefore, short- and long-term limit values were derived from human data. Experimental studies conducted with humans demonstrate effects after short-term exposure to concentrations at or above 400 microg NO2/m3. Effects on patients with light asthma could not be observed after short-term exposure to concentrations below 200 microg/m3. On basis of epidemiological long-term studies a threshold below which no effect on human health is expected could not be specified. Two short-term limit values have been proposed to protect public health: a 1-h value of 100 microg/m3 and a 24-h mean value of 50 microg/m3. Due to the limitations of epidemiological studies to disentangle effects of single pollutants, a long-term limit value cannot be easily derived. However, applying the precautionary principle, it is desirable to adopt an annual mean of 20 microg NO2/m3 as a long-term mean standard to protect public health.