September, 2011:

Executive Summary1 This report deals with answering what, at first glance, appear to be relatively simplequestions regarding the effects of particulate air pollution on mortality in the UK. Wehave tried to explain not only the approaches we have used to answer the questions,but also the limitations of the interpretations that can be put on the results. Weanticipate that it will be useful to policy makers and elected representatives, and hopealso that it will make a helpful contribution to public awareness and understanding ofthe health effects of air pollution. In summary:a Airborne particles comprise an anthropogenic component and a naturalcomponent.b There is an interest in the effects of air pollution on mortality in terms of theimpact that policies for reduction would have, or the current burden in termsof public health.c These effects can be expressed at the population level in terms of lifeexpectancy, and on loss or gain in life years. The burden can also be expressedin terms of deaths occurring in a specified year across the population.d As everyone dies eventually no lives are ever saved by reducing environmentalexposures – deaths are delayed resulting in increased life expectancy.e These measures are averages or aggregates across the population; it is notknown how the effects are distributed among individuals.2 We conclude that:a Removing all anthropogenic (‘human-made’) particulate matter air pollution(measured as PM2.5 1) could save the UK population approximately 36.5 millionlife years over the next 100 years and would be associated with an increase inUK life expectancy from birth, i.e. on average across new births, of six months.This shows the public health importance of taking measures to reduceair pollution.b A policy which aimed to reduce the annual average concentration of PM2.5 by1 μg/m3 would result in a saving of approximately 4 million life years or anincrease in life expectancy of 20 days in people born in 2008.c The current (2008) burden of anthropogenic particulate matter air pollution is,with some simplifying assumptions, an effect on mortality in 2008 equivalent …………………..

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http://www.sciencedaily.com/releases/2011/07/110706094329.htm

ScienceDaily (July 6, 2011) — A UK academic is calling for a nationwide study into the effects traffic pollution has on asthma sufferers after his own research in Cairo highlighted health problems in children who may even be affected while still in the womb.

Dr Mohammad Shamssain and his research team recently completed a study into the impact that high levels of air traffic pollution has on schoolchildren’s respiratory systems, allergies and conditions such as asthma.

Testing the lung functions of 1,397 children, aged 7-10, and measuring air pollution levels in Cairo, one of the world’s most traffic congested cities, assessed through the ISAAC questionnaire (The International Study of Asthma and Allergies in Childhood) Dr Shamssain discovered a high prevalence of asthma, wheezing, eczema and hay fever symptoms.

As part of his study — TRAP (Traffic Related Air Pollution) Dr Shamssain has been researching findings in other countries and discovered that air pollution causes two million premature deaths worldwide per year.

His research, which has been welcomed by Asthma UK, was recently presented at the biggest international chest conference: The American Thoracic Society International Conference in Colorado.

However, he says this kind of research needs more attention in the UK, and is now calling on the Department of Health and Research Funding Council to conduct more serious surveys in major cities such as London, Manchester, Birmingham Glasgow and Newcastle to assess the impact vehicle emissions are having on the local populations, especially children and the elderly.

“Our aim is to improve the respiratory health of children, as well as adults and the aging population, by studying lung function, respiratory symptoms and risk factors that might cause diseases like asthma and Chronic Obstructive Pulmonary Disease (COPD),” explained Dr Shamssain, a senior lecturer in human physiology — respiratory pathophysiology and epidemiology at the University of Sunderland.

“We have identified that pollutants such as nitrogen and sulphur dioxide as well as particle matter from vehicle exhausts and road dust is linked to the onset of asthma. The risk can start from the time a child is in the womb, as the placenta does not offer protection to mothers exposed to pollutants. Pollutants entering the fetal circulation have a significant impact on growth and development; there have also been cases of babies born with retardation, morbidity and low birth weight.

“Children in homes near roads with heavy traffic also have increased risk of new onset-asthma, incidence of wheeze, risk of recurrent dry coughs, hospitalisation and school absenteeism.”

He added: “We must encourage more research in this area on a large scale and launch an intervention strategy and awareness programme to reduce morbidity and mortality caused by ambient air pollutants.

“Reducing traffic exposure to children is expected to reduce the symptoms and prevalence of asthma. There could also be a long term cost saving to health agencies.”

To help improve the situation Dr Shamssain is proposing policy changes on pollution levels in towns and cities. Studies in Southern California showed that if ambient air pollution is reduced, annual asthma related emergency visits and hospitalisation decreased from 22 per cent to six per cent and bronchitis would decrease from 40 per cent to 20 per cent.

He also believes through awareness programmes relayed to parents, schools and children, personal exposure can be reduced by avoiding high level exposure and outdoor activities during periods of high pollution.

Finally, taking simple steps ourselves such as eating fruit, vegetables and taking vitamins A and C, can provide an antioxidant for the respiratory system.

He explained: “Antioxidants may strengthen defence mechanisms and reduce the harmful effects of air pollution. Studies suggest that dietary supplementation with sulforaphene, a potent inducer of antioxidant enzymes, reduces inflammatory responses, especially in those exposed to diesel exhaust particles.

“Sulforaphene is produced naturally by vegetables including Brussel sprouts, turnips, cabbage, broccoli and cauliflower, carrots, tomatoes, apples and oranges. Finally taking simple steps such as eating fresh fruit, vegetables and taking vitamins A & C, can provide an anti-oxidant for the respiratory system.”

Leanne Metcalf, Assistant Director of Research at Asthma UK, says: “We know that air pollution has a severe impact on the health and the quality of life of people with asthma; two thirds of people with asthma tell us that traffic fumes make their asthma worse and we are seeing increasing research evidence which suggests pollution may actually have a role to play in causing asthma in the first place.

“At Asthma UK we welcome any research that will help us to gain more insight into this area which could ultimately improve the lives of people with asthma in the future

http://www.sciencedaily.com/releases/2010/10/101005171042.htm

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ScienceDaily (Oct. 6, 2010) — Exposure to dirty air is linked to decreased function of a gene that appears to increase the severity of asthma in children, according to a joint study by researchers at Stanford University and the University of California, Berkeley.

While air pollution is known to be a source of immediate inflammation, this new study provides one of the first pieces of direct evidence that explains how some ambient air pollutants could have long-term effects.

The findings, published in the October 2010 issue of the Journal of Allergy and Clinical Immunology, come from a study of 181 children with and without asthma in the California cities of Fresno and Palo Alto.

The researchers found that air pollution exposure suppressed the immune system’s regulatory T cells (Treg), and that the decreased level of Treg function was linked to greater severity of asthma symptoms and lower lung capacity. Treg cells are responsible for putting the brakes on the immune system so that it doesn’t react to non-pathogenic substances in the body that are associated with allergy and asthma. When Treg function is low, the cells fail to block the inflammatory responses that are the hallmark of asthma symptoms.

The findings have potential implications for altered birth outcomes associated with polluted air, much the same as those noted for the effects of cigarette smoke.

“When it came out that cigarettes can cause molecular changes, it meant the possibility that mothers who smoked could affect the DNA of their children during fetal development,” said study lead author Dr. Kari Nadeau, pediatrician at Stanford’s Lucile Packard Children’s Hospital and an assistant professor of allergy and immunology at Stanford’s School of Medicine. “Similarly, these new findings suggest the possibility of an inheritable effect from environmental pollution.”

Forty-one participants came from the Fresno Asthmatic Children’s Environment Study (FACES), a longitudinal study led by principal investigator Dr. Ira Tager, professor of epidemiology at UC Berkeley’s School of Public Health, and co-principal investigator S. Katharine Hammond, UC Berkeley professor and chair of environmental health sciences. The researchers also recruited 30 children from Fresno who did not have asthma.

“I’m not aware of any other studies that have looked at how chemicals can alter cells so early in the regulatory process, and then connected that effect to clinical symptoms,” said Tager. “There are people who still question the direct link between air pollution and human health, but these findings make the health impact of pollutants harder to deny.”

Fresno was chosen because it is located in California’s Central Valley, where trapped hot air mixes with high traffic and heavy agriculture to create some of the highest levels of air pollution in the country. It is also a region known for its high incidence of asthma: Nearly one in three children there have the condition, earning Fresno the nickname, “The Asthma Capitol of California.”

The researchers compared the participants from Fresno with 80 children, half with asthma and half without, in the relatively low-pollution city of Palo Alto, Calif. The children were matched by age, gender and asthma status, among other variables. The children were tested for breathing function, allergic sensitivity and Treg cells in the blood.

Daily air quality data came from California Air Resources Board monitoring stations. The researchers calculated each child’s annual average exposure to polycyclic aromatic hydrocarbons (PAH), a byproduct of fossil fuel and a major pollutant in vehicle exhaust.

The study found that the annual average exposure to PAH was 7 times greater for the children in Fresno compared with the kids in Palo Alto. Levels of ozone and particulate matter were also significantly higher in Fresno.

Not surprisingly, the study found that the children in Fresno had lower overall levels of Treg function and more severe symptoms of asthma than the children in Palo Alto. For example, the non-asthmatic children in Fresno had Treg function results that were similar to the children with asthma in Palo Alto.

The study authors correlated increased exposure to PAH with methylation of the gene, Forkhead box transcription factor (Foxp3), which triggers Treg cell development. Methylation effectively disables the gene’s function, leading to reduced levels of Treg cells. The connection between Treg function and the severity of asthma symptoms held for children in both groups.

While previous studies have found associations between pollution — especially motor vehicle exhaust — and an increased risk of developing asthma, few have traced its molecular pathway so completely, the study authors said.

“The link between diesel exhaust and asthma could simply have been that the particulates were irritating the lungs,” said Nadeau. “What we found is that the problems are more systemic. This is one of the few papers to have linked from A to Z the increased exposure to ambient air pollution with suppressed Treg cell levels, changes in a key gene and increased severity of asthma symptoms.”

The researchers noted that Treg cells are important for other autoimmune disorders, so the implications of this study could go beyond asthma.

Other co-authors of the study are Dr. John Balmes, UC Berkeley professor of environmental health sciences; Elizabeth Noth and Boriana Pratt, UC Berkeley researchers at FACES; and Cameron McDonald-Hyman, research assistant at Stanford University’s School of Medicine.

The National Institutes of Health, U.S. Environmental Protection Agency and the American Lung Association helped support this research.

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http://www.cuhk.edu.hk/rtao/research/rhl/asthma.htm

Asthma is the commonest chronic childhood disease and a major reason for the admission of children to

hospital. There are approximately 120,000 children in Hong Kong with varying levels of asthma. Forty per cent of them need to visit specialty outpatient clinics from time to time. Those who are subsequently hospitalized make up 15 per cent of all children admitted to hospital. In recent years, the prevalence of asthma has been on the rise. Research at the University shows its prevalence in 1989 to be 4.8 per cent, and the figure rose to 11.2 per cent in 1995.

Higher Incidence Caused by the Environment

Prof. Gary Wong of the Department of Paediatrics pointed out that genetic alterations and environmental factors are the two main causes of asthma. But genes do not undergo major alterations within a period of six years, and while childhood asthma in Hong Kong is less prevalent than that in the West, it is far more prevalent than that on the mainland, which has a similar gene pool. All this indicates that the environment is the main reason for the drastic increase in childhood asthma prevalence in the territory in recent years. Statistics in the UK and Australia also show that childhood asthma has doubled in the past 10 years or so, which further confirms the environmental influence.

Prof. Wong said, ‘Environmental asthma allergens are very complex. There have been very few studies on asthma in Chinese children in the past, especially large-scale studies. In 1994 he conducted a small study comparing the prevalence of childhood asthma in Beijing, Guangzhou, and Hong Kong. The results show that the prevalence of the condition in Hong Kong is three times that in Guangzhou. This study triggered a large-scale comparative study in 1996 to investigate the role played by environmental risk factors. The project was supported by a grant of HK$692,000 from the Research Grants Council and led by Prof. Wong. The other team members included Prof. Fok Tai-fai of the Department of Paediatrics and Prof. Dr. Joseph Lau of the Centre for Clinical Trials and Epidemiological Research.

A Large-scale Comprehensive Study

The study, a collaboration with the Capital Institute of Beijing and the Guangzhou Institute of Respiratory Disease, covered 11,000 children aged 9 to 11 from the three cities. ‘The subjects, who come from different areas of the three places, were selected by random sampling. We asked their parents to give details about the children’s living environment since birth and their allergic reactions, including eye, skin, and nose allergies, whether there is rash and coughing, whether exercise and climate change cause wheezing, etc. The questionnaire is recognized internationally as a reliable tool for measuring childhood asthma, Prof. Wong remarked.

The research team then selected 1,000 participants from each of the three cities for a skin-prick test to observe their response to different allergens. Finally 200 children from each city were arranged to be given an airway sensitivity test. As the two tests were expensive and time-consuming, they could only be administered on a smaller sample. The researchers also conducted an environmental investigation into the homes of these children using standardized appraisal methods. They took samples of house dust from the bed, and the floors of the bedroom, living room, and kitchen, and measured the concentration of allergens using an immunity test.

Prof. Wong explained why no outdoor environmental data were gathered: ‘International asthma research has shown that air quality has no effect on asthma. For example, Chongqing is more polluted than Hong Kong, but the prevalence of childhood asthma there is only a fifth of that in Hong Kong.’

Hong Kong’s Asthmatic Children Double Those in
Beijing and Guangzhou

The study found that the number of local asthmatic children is double that of Beijing and Guangzhou (Figure 1). Factors identified as ‘high-risk’ include home smoking, maternal smoking, use of synthetic pillow and bedding, and use of gas as cooking fuel. ‘A baby whose mother smokes during pregnancy will have a narrower bronchial tube. If it continues to inhale second-hand smoke after birth, its bronchial tube will narrow even further, making it prone to infections and wheezing. Synthetic bedding and pillow contain oil ingredients which slowly release infection-causing and dust-attracting chemical gas. Cooking gas releases carbon monoxide and carbon dioxide, which trigger asthma symptoms, because some of the gases are not completely burnt in the process,’ Prof. Wong explained.

The prevalence of asthma is found to be lower among children who were breast-fed (the longer the better), have siblings in the home, and attend day care centres early on. Exposure to different viruses has been shown to boost their immune system.

Research conducted overseas have shown house dust and cats to be the most common allergens. Over 20 per cent of Guangzhou children are found to be allergic to house dust, compared to only 7 per cent for Beijing (Figure 2). Given the similar prevalence of asthma in the two cities, one can conclude that while house dust is an allergen in China, it is not as significant as in the West. The study also finds that children who are allergic to dust and cats have a three to four times greater chance of suffering from asthma than the normal person. Prof. Wong pointed out, however, that this only shows that these allergens may trigger an attack in asthma-sufferers but not that they cause asthma.

In conclusion, Prof. Wong said, ‘Asthma patients are a heavy burden on Hong Kong’s medical services. If they can learn to avoid certain risk factors in the environment, we can reduce its prevalence more effectively. We will continue to examine the link between environmental factors and asthma so as to find better preventive measures.’

The general misunderstanding that asthma is incurable or uncontrollable has led to neglect in management. Prof. Wong pointed out that although there is still inadequate knowledge of the causes of asthma, medical practitioners are able to treat it. Advances in technology have also raised the efficacy of medication.

Ten years ago, the rate of hospitalization of Hong Kong’s asthmatic children was 25 per cent, but it has now gone down to 10 to 15 per cent.

Prof. Wong said that the condition very often improves as the child grows up, but improper management over an extended period of time can cause permanent damage to the airway. The research team designed an education programme to explain to patients the underlying and precipitating causes of asthma, the rationale of different types of medication, and the proper use of treatment devices. Although there is no lasting cure for asthma yet, the disease can be put under good control with the right medication, which, if administered properly, will have no serious side effects and is not addictive. The condition of patients who have participated in the programme has been shown to have improved significantly, both in the recurrence rate and symptom manifestation. With proper treatment, asthmatic children can live normal and healthy lives.

SummaryObjective To examine the association of air pollutants with hospital admission for childhoodasthma in Hong Kong.Methods Data on hospital admissions for asthma, influenza and total hospital admissions inchildren aged418 years at all Hospital Authority hospitals during 1997–2002 were obtained.Data on daily mean concentrations of particles with aerodynamic diameter o10 mm (i. e.PM10) and o2.5 mm (i. e. PM2.5), nitrogen dioxide (NO2), sulphur dioxide (SO2), and ozone(O3) and data on meteorological variables were associated with asthma hospital admissionsusing Poisson’s regression with generalized additive models for correction of yearly trend,temperature, humidity, day-of-week effect, holiday, influenza admissions and total hospitaladmission. The possibility of a lag effect of each pollutant and the interaction of differentpollutants were also examined.Results The association between asthma admission with change of NO2, PM10, PM2.5 and O3levels remained significant after adjustment for multi-pollutants effect and confoundingvariables, with increase in asthma admission rate of 5.64% (3.21–8.14) at lag 3 for NO2, 3.67%(1.52–5.86) at lag 4 for PM10, 3.24% (0.93–5.60) at lag 4 for PM2.5 and 2.63% (0.64–4.67) atlag 2 for O3. Effect of SO2 was lost after adjustment.Conclusion Ambient levels of PM10, PM2.5, NO2 and O3 are associated with childhood asthmahospital admission in Hong Kong.Keywords air pollution, asthma, children, Hong Kong, hospital admissionSubmitted 25 November 2005; revised 21 April 2006; accepted 7 June 2006

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