Monday, 20 April 2015

Urban green spaces: Insights from Valencia

Visiting the city of Valencia in Spain for the first time, we were pleasantly greeted by the subtle aroma of orange blossoms in the air and the sight of beautiful oranges dangling from the orange trees that line the street pavements. Whilst many parts of the city are bordered with trees, there are also other green spaces,  such as beautiful small parks (like the one in the picture  shown below),
complete with Mediterranean flora such as palms, ficus, cycas, and orange trees. 




 The most impressive green space is perhaps the 9 km green belt that runs through the city-  the Jardi delTuria (Garden of the Turia), which is a credit to the city. The Turia is a Spanish river that empties into the Mediterranean near the city of Valencia. In 1957, it flooded and devastated Valencia. Consequently, the course of the river was artifically changed- now running along the city edge before meeting the Mediterranean. The original course of the river continues has been converted into an enormous green space resplendent with beautiful trees with pedestrian paths, cycle paths, and occasionally dotted with football grounds, cafes, athletics tracks, and gardens within the garden. Here city dwellers relax, play, or just get about their business, avoiding the traffic that plies overhead on the many bridges that cross the river bed. Buildings tower over either side of the Turia garden, comprising largely of apartment blocks and businesses. Our walk along the Turia garden in sweltering sunny April was very pleasant which made me realize the importance of green spaces in cities.



Urban heat islands and global warming

Cities have their own micro-climates. Human activities- buildings made of concrete and asphalt, vehicular emissions, heat generated by people, and heat arising from equipment use, all contribute to temperature increases in the urban areas to levels that are significantly higher from the adjoining rural areas where temperatures remains close to air temperatures. Such urban areas are called ‘Urban heat islands’, a concept described over 200 years ago by Luke Howard, the father of meteorology. The term has been coined  as the warmer urban air lies in a ‘sea’ of cooler rural air.  According to the EPA, the annual mean air temperature of a city with 1 million people or more can be 1.8–5.4°F (1–3°C) warmer than its surroundings, going up to temperature difference as much as 22°F (12°C) on a clear, calm night.

Heat islands could not only affect the health of the urban inhabitants by causing heat -related illnesses (a topic discussed in the earlier post), but also contribute to global warming in general, and must not be ignored particularly as predictions indicate that by 2050 about 64% of the developing world and 86% of the developed world will be urbanised - leading to amplification of the issue. Whilst urbanisation cannot be halted, it must be made sustainable.

Mitigation strategies for urban heat island effects

Among the four major strategies United States EnvironmentalProtection Agency (EPA) has suggested for mitigating the effects of urban heat islands, the first one is increasing tree and vegetation cover. The others are the installation of green roofs (roofs with plants grown over a waterproof membrane), installation of cool and reflective roofs (built from materials with high solar reflectance and high heat emittance), and building cool pavements (made of material with high solar reflectivity and good water permeability).

In this post, we will look at the EPA’s primary recommendation. This, in my opinion, is the one with the maximum impact and the least costliest. The major benefits of increasing trees and vegetation covers are the following:
They reduce surface and air temperatures by providing shade and by the process of evapotranspiration. Estimates indicate that evapotranspiration, alone or in combination with shading, can help reduce peak summer temperatures by 2–9°F (1–5°C). By providing shade to buildings, trees decrease the demand for air conditioning and indirectly decrease the need for energy use which, in turn, lowers greenhouse gas emissions and provides better air quality. Trees also function as ‘sinks’ for air pollutants and carbon dioxide. Trees improve the quality of life of city dwellers by enhancing the aesthetic value of their surroundings and promote biodiversity by providing habitats for diverse species.

Interestingly, it  also appears that for some trees living in an urban environment might not be bad after all. In a study in 2012, seedlings of oak were grown for one season at four sites along an urban–rural transect from Central Park in New York City to the Catskill Mountains in upstate New York  with a difference in average maximum temperatures of 2.4 °C and  difference in minimum temperatures of 4.6 °C.  Additionally, seedlings were cultured in growth cabinets simulating the seasonal differential between the city and rural sites. The researchers found that warmer temperatures associated with the urban environment, especially high night-time temperatures, lead to enhanced growth in these seedlings.

The necessity for a Green Channel Programme for our cities

Coming back to our example - Valencia- it appears that the city is going in the right direction with its tree and vegetation cover initiatives. The green spaces and the green belts are not only aesthetically pleasing, but also reduce the heat (personal experience). Increasing the vegetation cover in cities is something where more is less. Thus, Valencia and other cities who have such initiatives cannot rest on their laurels. We really need to have green channels through our cities to cool the urban heat islands.


References

http://www.valenciavalencia.com/sights-guide/turia.htm
http://www.epa.gov/heatisland/about/index.htm

Searle, S., Turnbull, M., Boelman, N., Schuster, W., Yakir, D., & Griffin, K. (2012). Urban environment of New York City promotes growth in northern red oak seedlings Tree Physiology, 32 (4), 389-400 DOI: 10.1093/treephys/tps027http://dx.doi.org/10.1093/treephys/tps027">10.1093/treephys/tps027
>


Tuesday, 14 April 2015

Global Temperature Rise and Human Health - How is the World Coping?






Global temperatures have been on the rise since the Industrial Age due to human activity such as the emissions of greenhouse gases from fossil fuel burning, large-scale deforestation, expansion of urban areas where vegetation cover is replaced by artificial heat retaining materials such as asphalt and concrete, some agricultural practices, and waste management activities. Data from the National Climatic Data Centre that  maintains the world's largest climate data archive indicate that the average global temperature across land surfaces was 1.68°C (3.02°F) above the 20th century average of 3.2°C (37.8°F) . To put things in perspective, February 2015 was much warmer than February 2014.

 Epidemiological studies in different parts of the world have unequivocally shown a strong link between high temperature and mortality, which is a public health concern. The magnitude of the problem will only escalate as the global mean temperature continues to increase causing extreme heat events in large geographical areas. Approximately 650 deaths per year occur in United States due to heat events, which account for more fatalities than any other weather hazard. Males outnumber females in deaths cause by extreme heat events.


Vulnerable population for heat-related deaths


 Although the human body can tolerate changes in temperature by the process of thermoregulation, whereby it can protect itself from extremes in ambient temperature, there are limits. Importantly, infants and the elderly particularly those with health conditions such as cardiovascular disease, cerebrovascular disease, neurological diseases, diabetes, renal disease and respiratory disease are particularly vulnerable to mortality due to increase in ambient temperature. However, many studies indicate that there is a lack of risk perception among the population to heat-related deaths.


Global disparity in knowledge pertaining to extreme heat, its consequences, and public health responses  


 In many developed nations, data on temperature rise and its consequences on health are often readily available due to good documentation of historical temperature records and epidemiological research in these areas. Heat vulnerability maps (Heatwave maps) now exist for many areas in developed countries- particularly cities, that help identify regions that are at risk for extreme heat events. In many such places, Heat response plans that help prepare communities for heath rated illnesses exist.
However, developing nations lag behind both in research as well as public health strategies to mitigate extreme heat events. A plethora of factors such as  knowledge gaps, defective record keeping and poor research (death records, which list causes of death are often unreliable particularly in rural areas), archaic technology, lack of funds, corruption, poor public health initiatives, all lead to poor knowledge  or ignorance  pertaining to the health effects of extreme temperature. The health implications of extreme heat  is likely to be  far more pronounced in the developing countries, which are often subject to extreme climate change compared to the developed countries, but is likely staying under the radar.

Here through the pages of Ecoratorio, we have often highlighted the dangers of human activities on the environment and the need for global, personal, and corporate environmental stewardship. Specifically in the context of heat-related illnesses and deaths, a cohesive understanding of the environmental impact on human health, identification of vulnerable populations, expert recommendations on public behaviour and timely communication of these recommendations, generating public awareness through mass media of health-related illnesses and deaths, and enforcement of mitigation steps in the general public is critical. With extreme heath events anticipated to rise in the coming years due to climate change, population increase, and increase in ageing population, it is crucial that  scientific, political and public health action should take place to manage this important issue.



Useful Facts about Heat-related illnesses

  • Although many studies have stressed infants and elderly as being most vulnerable to heat –related illnesses and death, other high-risk groups include young children, older adults (people over 65 years) and people who engage in strenuous activities outdoors.
  • Extreme heat events disproportionately harm vulnerable populations.
  • The majority of heat-related deaths are preventable.
  • During periods of extreme heat, heat-related illnesses can be prevented by using air-conditioning, avoiding strenuous outdoor activities, drinking adequate amounts of fluid, wearing lightweight clothing, and avoiding alcohol consumption. 
  •  Heat Response plans should be in place before extreme heat events occur.
  • Major inequalities exist between developed and the developing nations in the awareness of heat- related illnesses, the contributory factors, and public health initiatives.
References:

  1. http://www.ncdc.noaa.gov/sotc/global/
  2.  http://monash.edu/news/show/heatwave-map-reveals-melbournes-most-vulnerable-postcodes
  3.  Madrigano, J., Ito, K., Johnson, S., Kinney, P., & Matte, T. (2015). A Case-Only Study of Vulnerability to Heat Wave–Related Mortality in New York City (2000–2011) Environmental Health Perspectives DOI: 10.1289/ehp.1408178http://dx.doi.org/10.1289/ehp.1408178">10.1289/ehp.1408178>
  4. Kim, C., Lim, Y., Woodward, A., & Kim, H. (2015). Heat-Attributable Deaths between 1992 and 2009 in Seoul, South Korea PLOS ONE, 10 (2) DOI: 10.1371/journal.pone.0118577http://dx.doi.org/10.1371/journal.pone.0118577">10.1371/journal.pone.0118577>
  5. http://www.epa.gov/climatechange/science/indicators/health-society/heat-deaths.html
  6. Bobb, J., Peng, R., Bell, M., & Dominici, F. (2014). Heat-Related Mortality and Adaptation to Heat in the United States Environmental Health Perspectives DOI: 10.1289/ehp.1307392http://dx.doi.org/10.1289/ehp.1307392">10.1289/ehp.1307392>
  7. http://www.medscape.com/viewarticle/806947

Monday, 8 July 2013

Humans vs Tigers

I have been following an interesting news of a match of Humans vs Tigers. The eventual outcome was a draw: one man and a tiger cub killed on each side.

 The story is that six men from Simpang Kiri village in Aceh Tamiang district went to the Mount Leuser National Park on Sumatra Island for harvesting agarwood (used in incense and perfume). I am assuming that this was probably illegal since national parks does have restricted entry and harvesting this precious material is probably regulated. Nonetheless, they set traps to catch deer (again, I am unsure about whether this amounts to poaching) and caught a Sumatran tiger (Panthera tigris sumatrae) cub instead (which eventually died). This action attracted 5-7 tigers in the vicinity who, quite notably, chased the men. The men climbed up some trees and hung on to dear life for five days, subsisting on rainwater. The tigers, equally persistent, remained at the base. One man was mauled to death when he fell down after a branch snapped. The others contacted nearby villagers via the cell phones. The villagers were helpless, but eventually "tamers" and the rescue team drove the tigers away.

 I could debate at length about whether the men deserved the plight they faced, but more interesting is the behaviour of the tigers. The Sumatran tiger is the smallest (75-140 kg - Prothero et al, 2012) and is critically endangered (Sunarto et al, 2013). It is endemic to, well, Sumatra and the population is around 350. The low numbers are due to deforestation and conversion of lands into acacia and oil palm plantations, fires, and poaching (O'Brien et al, 2003; Sunarto et al, 2012; Johnson, 2013) . This plight was recently highlighted by Sunarto et al, 2013, who calculated that numbers were much lower in the Riau province which was believed to have the highest concentration of tigers (Banerjee, 2012, state that the population had declined by 70%; from 640 in 1982, the numbers fell to 192 in 2007). In a previous paper, the same authors proved that tigers are not particularly fond of plantations and settlements, preferring large contiguous and undisturbed forests and higher altitudes. However, the authors also encourage using the plantations as "corridors, stepping stones, or mosaics of connectivity facilitating animal movement"- which, in my humble opinion, is a recipe for disaster for both tigers and humans.

Indeed, it is sad that a human life and a tiger life were lost. But it could have gone in a few different ways. Five other humans could have been killed. So could have 5-6 critically endangered tigers. We very seldom recognise how our lifestyle preferences (I too have found agarwood to be particularly heady) might be only aggravating human-animal conflict elsewhere...

 Image source: http://www.istockphoto.com/stock-photo-2885355-b-w-sumatran-tiger.php

References Kimberly Elizabeth Johnson (2013). Living Off the Fat of Another Land: Trans Fat Social Policy and Environmental Externalities Environmental Policy is Social Policy – Social Policy is Environmental Policy, 37-50 DOI: 10.1007/978-1-4614-6723-6_4  
Timothy G. O'Brien, Margaret F. Kinnaird, Hariyo T. Wibisono (2003). Crouching tigers, hidden prey: Sumatran tiger and prey populations in a tropical forest landscape Animal Conservation, 6, 131-139 DOI: 10.1017/S1367943003003172
Donald R. Prothero, Valerie J. Syverson, Kristina R. Raymond, Meena Madan, Sarah Molina, Ashley Fragomeni, Sylvana DeSantis, Anastasiya Sutyagina, Gina L. Gage, Size and shape stasis in late Pleistocene mammals and birds from Rancho La Brea during the Last Glacial–Interglacial cycle, Quaternary Science Reviews, Volume 56, 21 November 2012, Pages 1-10, ISSN 0277-3791, http://dx.doi.org/10.1016/j.quascirev.2012.08.015.

Sunarto Sunarto, Marcella J. Kelly, Karmila Parakkasi, Sybille Klenzendorf, Eka Septayuda, & Harry Kurniawan (2012). Tigers Need Cover: Multi-Scale Occupancy Study of the Big Cat in Sumatran Forest and Plantation Landscapes PLoS One DOI: 10.1371/journal.pone.0030859  

S Sunarto, Marcella J. Kelly, Sybille Klenzendorf, Michael R. Vaughan, Zulfahmi, M.B. Hutajulu, & Karmila Parakkasi (2013). Threatened predator on the equator: multi-point abundance estimates of the tiger Panthera tigris in central Sumatra Oryx, 47 (2), 211-220 DOI: 10.1017/S0030605311001530

Tuesday, 5 February 2013

Automobile exhausts and heart disease: Is the link an inflammatory molecule?


A recent study in America found evidence for increased levels of IL-1 beta,  a marker associated with inflammation in the blood of people who lived near the highways and had high exposures to vehicular exhausts.

As our consumption and usage of vehicles increases, our roads constantly brew  more particulate matter, black carbon, nitrogen dioxide, sulphur-di-oxide and carbon monoxide, all emitted from automobile exhausts. The danger about these emissions is that they don’t just stay there, but drift. Our busy highway and motorways, which have high traffic volume, are the worst offenders. Studies indicate that people living/working in such areas and spending significant time within approximately 200m of highways are exposed heavily to these pollutants compared to people who are based further away. Unsurprisingly, the exposures at highways are higher when compared to people living on busy urban streets.

A plethora of studies have linked vehicular emission exposure to heart disease. We had highlighted a couple of them in this blog. The closer people live or work near highways/motorways, the greater is their exposure to the  harmful effluents.  However, many of the studies in this field  of research are epidemiological in nature which are population based and  subject to the criticism that the observed correlation in the studies might not really signify causality. A recent study by researchers from Tufts School of Medicine, Boston, attempts to close the gulf and provides a molecular basis of the effects of vehicular emission exposure on human health and offers an explanation on how automobile exhausts could cause heart diseases. 

The study was conducted in the  Somerville area of  Massachusetts, USA.  The scientists compared blood samples from 20 people who lived less than 100m from the Interstate-93( a highway that connects Massachusetts to Vermont) and those residing a km away from the highway in urban backgrounds. To ensure that the  two groups were as  similar as possible,  the subjects in both groups were matched to age, gender and education. Though there were no significant differences between two groups in terms of body measurements (height, weight) and education, the group who lived in urban backgrounds were more likely to earn less, had higher exposure to vehicle exhausts that was occupationally related and high levels of bad cholesterols (LDL). The researchers factored the job related vehicle emission exposure in their calculations and found that the levels of IL-1 beta was increased significantly in those people who lived near the highway.

Inflammation plays a crucial role in the development and progression of a variety of heart diseases importantly atherosclerosis and congestive heart failure.  Inflammatory molecules linked to these processes includes interleukin-1 (IL-1), but this American study  is the first of its kind where such a link has been shown to occur  in humans with proximity to heavy traffic. The results are notable as it also recapitulates the trend shown by particulate matter  in increasing the  levels of   IL -1 family  in  animal models and cells in culture. In their paper, the researchers also point out that  IL-1 beta itself could have application as a biological marker of air pollution exposure. However, one thing to note is that  IL-1 family is also influenced by diet and this is a factor that has to be controlled for in further experiments. Cumulatively, the study by Professor Brugge and his colleagues  is a very interesting preliminary work which warrants larger carefully controlled follow up studies.


References:
Fearon, W., & Fearon, D. (2008). Inflammation and Cardiovascular Disease: Role of the Interleukin-1 Receptor Antagonist Circulation, 117 (20), 2577-2579 DOI: 10.1161/CIRCULATIONAHA.108.772491 ResearchBlogging.org Brugge, D., Durant, J., & Rioux, C. (2007). Near-highway pollutants in motor vehicle exhaust: A review of epidemiologic evidence of cardiac and pulmonary health risks Environmental Health, 6 (1) DOI: 10.1186/1476-069X-6-23 Brugge, D., Lane, K., Stewart, A., Tai, A., & Woodin, M. (2013). Highway Proximity Associations with Blood Markers of Inflammation: Evidence for a Role for IL-1β Journal of Toxicology and Environmental Health, Part A, 76 (3), 201-205 DOI: 10.1080/15287394.2013.752325

Wednesday, 30 January 2013

Pussy Cat, Pussy cat, what have you killed?



In the early eighties, our parents rescued two abandoned stray kittens from the road, which started a long line of cat dynasty in our house and the neighbourhood. Our house gained the reputation of being a sanctuary for abandoned cats, that we had people stealthily abandoning their cats outside our house gates. At one point, we had about 12 cats in the house. We loved these animals dearly; but despite being fed adequately, we were horrified to note that they killed squirrels, birds, bats, bandicoots, rats and mice. We lamented their notorious habit of murdering birds and squirrels, particularly as we fed them too, and could never comprehend how our adorable pets could turn into merciless masochistic killers, particularly as they never ate their kill. The carcass was presented for us to see almost very time.  I remember one time when my mother was inconsolable, when a cat killed one of ‘her’ doves that she had grown so attached to. Our repeated efforts to teach the cats 'good behaviour' was not fruitful.  

The  results presented in recent paper in Nature Communications by Loss and his colleagues on the 'The impact of free-ranging domestic cats on wildlife of the United States' was not a surprise in one respect ,as we all know that cats kill birds and smaller mammals. However, what was surprising was the magnitude of the effects. Domestic cats have been introduced globally by man and are linked to the extinction of several animals on islands, whilst their effect on other places had not been scientifically estimated. In their study, the authors estimate that in the US, domestic cats alone kill 1.4-3.7 billion birds and 6.9-20.7 billion mammals every year, and that cats that are not owned (feral cats) as opposed to owned pets, cause the majority of the killing. What is different about the study when compared to previous ones, is the actual quantification the authors conducted, which suggest that cats cause significant and substantial wildlife mortality than previously thought. Interestingly, these cute and cuddly creatures which are the most popular pets in the world are the primary and greatest source of anthropogenic (caused by humans- in this case indirectly) mortality for US birds and mammals. This makes me wonder, whether their new found notoriety would affect their popularity as pets. For some reason, I doubt it.


References:
1. http://www.tau.ac.il/lifesci/zoology/members/yom-tov/inbal/cats.pdf
2. Loss, S., Will, T., & Marra, P. (2013). The impact of free-ranging domestic cats on wildlife of the United States Nature Communications, 4 DOI: 10.1038/ncomms2380

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