Long-term exposure to ambient air pollution and road traffic noise and asthma incidence in adults: The Danish Nurse cohort

BACKGROUND

Ambient air pollution is likely a risk factor for asthma, and recent evidence suggests the possible relevance of road traffic noise.

OBJECTIVES

We examined the associations of long-term exposure to air pollution and road traffic noise with adult-asthma incidence.

METHODS

We followed 28,731 female nurses (age > 44 years) from the Danish Nurse Cohort, recruited in 1993 and 1999, for first hospital contact for asthma from 1977 until 2015. We estimated residential annual mean concentrations of particulate matter with diameter < 2.5 µm (PM_2.5) since 1990 and nitrogen dioxide (NO₂) since 1970 with the Danish DEHM/UBM/AirGIS modeling system, and road traffic noise (L_den) since 1970 with the Nord2000 model. Time-varying Cox regression models were used to associate air pollution and road traffic noise exposure with asthma incidence.

RESULTS

During 18.6 years' mean follow-up, 528 out of 23,093 participants had hospital contact for asthma. The hazard ratios (HR) and 95% confidence intervals for asthma incidence associated with 3-year moving average exposures were 1.29 (1.03, 1.61) per 6.3 µg/m³ for PM_2.5, 1.16 (1.07, 1.27) per 8.2 µg/m³ for NO₂, and 1.12 (1.00, 1.25) per 10 dB for L_den. The HR for NO₂ remained unchanged after adjustment for either PM_2.5 or L_den, while the HRs for PM_2.5 and L_den attenuated to unity after adjustment for NO₂.

CONCLUSIONS

Long-term exposure to air pollution was associated with adult-asthma incidence independently of road traffic noise, with NO₂ most relevant. Road traffic noise was not independently associated with adult-asthma incidence.

Altitude above 1500 m is a major determinant of asthma incidence. An ecological study

BACKGROUND

Previous studies suggest an inverse correlation between asthma and altitude. In the present work, we performed an in-depth analysis of asthma incidence in the 758 Mexican counties covered by the largest medical institution in the country (∼37.5 million insured subjects), and evaluated its relationships with altitude and other factors.

METHODS

Asthma incidence in each county was calculated from new cases diagnosed by family physicians. Other variables in the same counties, including selected diseases, geographical variables, and socioeconomic factors, were also obtained and their association with asthma was evaluated through bivariate and multivariate analyses.

RESULTS

Median asthma incidence was 296.2 × 100,000 insured subjects, but tended to be higher in those counties located on or near the coast. When asthma incidence was plotted against altitude, a two-stage pattern was evident: asthma rates were relatively stable in counties located below an altitude of ∼1500 m, while these rates progressively decreased as altitude increased beyond this level (r_S = -0.51, p < .001). Multivariate analysis showed that, once each variable was adjusted by the potential influence of the others, asthma incidence was inversely correlated with altitude (standardized β coefficient, -0.577), helminthiasis (-0.173), pulmonary tuberculosis (-0.130), and latitude (-0.126), and was positively correlated with acute respiratory tract infection (0.382), pneumonia (0.289), type 2 diabetes (0.138), population (0.108), and pharyngotonsillitis (0.088), all with a p ≤ .001.

CONCLUSION

Our study showed that altitude higher than ∼1500 m comprises a major factor in determining asthma incidence, with the risk of new-onset asthma decreasing as altitude increases. Other less influential conditions were also identified.

Association of PM2.5 with diabetes, asthma, and high blood pressure incidence in Canada: A spatiotemporal analysis of the impacts of the energy generation and fuel sales

Numerous studies have reported an association between fine particulate matter (PM_2.5) and human health. Often these relationships are influenced by environmental factor that varies spatially and/or temporally. To our knowledge, there are no studies in Canada that have considered energy generation and fuel sales as PM_2.5 effects modifiers. Determining exposure and disease-specific risk factors over space and time is crucial for disease prevention and control. In this study, we evaluated the association of PM_2.5 with diabetes, asthma, and High Blood Pressure (HBP) incidence in Canada. Then we explored the impact of the energy generation and fuel sales on association changes. We fit an age-period-cohort as the study design, and we applied an over-dispersed Poisson regression model to estimate the risk. We conducted a sensitivity analysis to explore the impact of variation in clean energy rates and fuel sales on outcomes changes. The study included 117 health regions in Canada between 2007 and 2014. Our findings showed strong association of PM_2.5 with diabetes, asthma, and HBP incidence. A two-year increase of 10μg/m³ in PM_2.5 was associated with an increased risk of 5.34% (95% CI: 2.28%; 12.53%) in diabetes incidence, 2.24% (95% CI: 0.93%; 5.38%) in asthma incidence, and 8.29% (95% CI: 3.44%; 19.98%) in HBP incidence. Our sensitivity analysis findings suggest higher risks of diabetes, asthma and HBP incidence when there is low clean energy generation. On the other hand, we found lower risk when we considered high rate of clean energy generation. For example, considering only diabetes incidence, we found that the risk in health regions with low rates of clean electricity is approximately 700% higher than the risk in health regions with high rates of clean electricity. Furthermore, our analysis suggested that the risk in regions with low fuel sales is 66% lower than the risk is health regions with low rates of clean electricity. Our study provides support for the creation of effective environmental health public policies that take into account the risk factors present in Canadians health regions.

The global decline in asthma death rates: can we relax now?

Whilst global asthma mortality seems to be decreasing, childhood asthma incidence is rising, and early warnings from Australia show an increase in asthma-related deaths in under-15s; this article considers whether we should view the future impact of asthma with trepidation. Age-adjusted mortality statistics for asthma have been reevaluated to provide an international standard. Comparisons across regions and time are complex, yet over the last two decades asthma mortality has clearly decreased, coinciding with a significant change in asthma management. The majority of remaining asthma deaths are preventable. Nonetheless, ongoing vigilance is required. Asthma remains under-diagnosed and under-treated. Childhood asthma has become more common; it is a matter of debate whether it is also more severe. Rather than being encouraged by the fall in numbers of asthma deaths, we should focus on the surging numbers of children suffering from the disease - and the worrying increase in asthma death rates in Australian children - and work to avert future issues.