Study on the formation and transport of ozone in relation to the air quality management and vegetation protection in Tenerife (Canary Islands)

Saharan Dust Events in the Dust Belt -Canary Islands- and the Observed Association with in-Hospital Mortality of Patients with Heart Failure

Recent studies have found increases in the cardiovascular mortality rates during poor air quality events due to outbreaks of desert dust. In Tenerife, we collected (2014–2017) data in 829 patients admitted with a heart failure diagnosis in the Emergency Department of the University Hospital of the Canaries. In this region, concentrations of PM₁₀ and PM_2.5 are usually low (~20 and 10 µg/m³), but they increase to 360 and 115 μg/m³, respectively, during Saharan dust events. By using statistical tools (including multivariable logistic regressions), we compared in-hospital mortality of patients with heart failure and exposure to PM₁₀ and PM_2.5 during dust and no-dust events. We found that 86% of in-hospital heart failure mortality cases occurred during Saharan dust episodes that resulted in PM₁₀ > 50 µg/m³ (interquartile range: 71–96 µg/m³). A multivariate analysis showed that, after adjusting for other covariates, exposure to Saharan dust events associated with PM₁₀ > 50 µg/m³ was an independent predictor of heart failure in-hospital mortality (OR = 2.79, 95% CI (1.066–7.332), p = 0.03). In conclusion, this study demonstrates that exposure to high Saharan dust concentrations is independently associated with in-hospital mortality in patients with heart failure.

Short-term effects of ultrafine particles on daily mortality by primary vehicle exhaust versus secondary origin in three Spanish cities

BACKGROUND

Evidence on the short-term effects of ultrafine particles (with diameter<100nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution.

METHODS

We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N). The first component accounts for aerosol constituents emitted by vehicle exhaust (N1) and the second for the photochemical new particle formation enhancements (N2). We applied city-specific Poisson regression models, adjusting for long-term trends, temperature and population dynamics.

RESULTS

Mean BC levels were higher in Barcelona and Tenerife (1.8 and 1.2μg·m^-3, respectively) than in Huelva (0.8μg·m^-3). While mean UFP concentrations were similar in the three cities, from which N1 was 40% in Barcelona, 46% in Santa Cruz de Tenerife, and 27% in Huelva. We observed an association with N1 and daily mortality in Barcelona, by increasing approximately 1.5% between lags 0 and 2, per an interquartile increase (IQR) of 3277cm^-3, but not with N2. A similar pattern was found in Santa Cruz de Tenerife, although none of the associations were significant. Conversely, in the industrial city of Huelva mortality was associated with N2 at lag 0, by increasing 3.9% per an IQR of 12,032·cm^-3.

CONCLUSION

The pattern and origin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account.

Trends and patterns of air quality in Santa Cruz de Tenerife (Canary Islands) in the period 2011-2015

Air quality trends and patterns in the coastal city of Santa Cruz de Tenerife (Canary Islands, Spain) for the period 2011-2015 were analyzed. The orographic and meteorological characteristics, the proximity to the African continent, and the influence of the Azores anticyclone in combination with the anthropogenic (oil refinery, road/maritime traffic) and natural emissions create specific dispersion conditions. SO₂, NO₂, PM₁₀, PM_2.5, and O₃ pollutants were assessed. The refinery was the primary source of SO₂; EU hourly and daily average limit values were exceeded during 2011 and alert thresholds were reached in 2011 and 2012. WHO daily mean guideline was occasionally exceeded. Annual averages in the three stations that registered the highest concentrations in 2011 and 2012 were between 9.3 and 20.4 μg/m³. The spatial analysis of SO₂ concentrations with respect to prevailing winds corroborates a clear influence of the refinery to the SO₂ levels. In 2014 and 2015, the refinery did not operate and the concentrations fell abruptly to background levels of 2.5-7.1 μg/m³ far below from WHO AQG. NO₂ EU limit values, as well as WHO AQG for the period 2011-2015, were not exceeded. The progressive dieselization of the vehicle fleet caused an increment on NO₂ annual mean concentrations (from 2011 to 2015) measured at two stations close to busy roads 25 to 31 μg/m³ (+21%) and 27 to 35 μg/m³ (+29%). NO _x daily and weekly cycles (working days and weekends) were characterized. An anti-correlation was found between NO _x and O₃, showing that O₃ is titrated by locally emitted NO. Higher O₃ concentrations were reported because less NO _x emitted during the weekends showing a clear weekend effect. Saharan dust intrusions have a significant impact on PM levels. After subtracting natural sources contribution, none of the stations reached the EU maximum 35 yearly exceedances of daily means despite seldom exceedances at some stations. None of the stations exceeded the annual mean EU limit values; however, many stations exceeded the annual mean WHO AQG. Observed PM₁₀ annual average concentrations in all the stations fluctuated between 10.1 and 35.3 μg/m³, where background concentrations were 6.5-24.4 μg/m³ and natural contributions: 4.2-9.1 μg/m³. No PM₁₀ temporal trends were identified during the period except for an effect of washout due to the rain: concentrations were lower in 2013 and 2014 (the most rainy years of the period). None of the stations reached the PM_2.5 annual mean EU 2015 limit value. However, almost all the stations registered daily mean WHO AQG exceedances. During 2015, PM_2.5 concentrations were higher than the previous years (2015, 8.8-12.3 μg/m³; 2011-2014, 3.7-9.6 μg/m³). O₃ complied with EU target values; stricter WHO AQG were sometimes exceeded in all the stations for the whole time period.

Integrated assessment of air pollution using observations and modelling in Santa Cruz de Tenerife (Canary Islands)

The present study aims to analyse the atmospheric dynamics of the Santa Cruz de Tenerife region (Tenerife, Canary Islands). This area is defined by the presence of anthropogenic emissions (from a refinery, a port and road traffic) and by very specific meteorological and orographic conditions-it is a coastal area with a complex topography in which there is an interaction of regional atmospheric dynamics and a low thermal inversion layer. These factors lead to specific atmospheric pollution episodes, particularly in relation to SO2 and PM10. We applied a methodology to study these dynamics based on two complementary approaches: 1) the analysis of the observations from the air quality network stations and 2) simulation of atmospheric dynamics using the WRF-ARW/HERMESv2/CMAQ/BSC-DREAM8b and WRF-ARW/HYSPLIT modelling systems with a high spatial resolution (1×1 km(2)). The results of our study show that the refinery plume plays an important role in the maximum SO2 observed levels. The area of maximum impact of the refinery is confined to a radius of 3 km around this installation. A cluster analysis performed for the period: 1998-2011 identified six synoptic situations as predominant in the area. The episodes of air pollution by SO2 occur mainly in those with more limited dispersive conditions, such as the northeastern recirculation, the northwestern recirculation and the western advection, which represent 33.70%, 11.23% and 18.63% of the meteorological situations affecting the study area in the year 2011, respectively. In the case of particulate matter, Saharan dust intrusions result in episodes with high levels of PM10 that may exceed the daily limit value in all measurement station; these episodes occur when the synoptic situation is from the east (3.29% of the situations during the year 2011).

Photosynthesis, chloroplast pigments, and antioxidants in Pinus canariensis under free-air ozone fumigation

High O3 levels, driving uptake and challenging defense, prevail on the Canary Islands, being associated with the hot and dry summers of the Mediterranean-type climate. Pinus canariensis is an endemic conifer species that forms forests across these islands. We investigated the effects of ozone on photosynthesis and biochemical parameters of P. canariensis seedlings exposed to free-air O3 fumigation at Kranzberg Forest, Germany, where ambient O3 levels were similar to those at forest sites in the Canary Islands. The twice-ambient O3 regime (2 x O3) neither caused visible injury-like chlorotic or necrotic spots in the needles nor significantly affected violaxanthin, antheraxanthin and zeaxanthin levels and the de-epoxidation state of the xanthophyll cycle. In parallel, stomatal conductance for water vapour, net photosynthesis, intercellular CO2 concentration, chlorophyll fluorescence parameters, as well as antioxidant levels were hardly affected. It is concluded that presently prevailing O3 levels do not impose severe stress on P. canariensis seedlings.