International Journal of Medicine and Public Health, Vol 7, Issue 1, Jan-Mar, 2017 56 Original Article Characteristics of the Ozone pollution and its Health Effects in India

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International Journal of Medicine and Public Health, Vol 7, Issue 1, Jan-Mar, 2017 56 Original Article Characteristics of the Ozone pollution and its Health Effects in India

April 06, 2017 - 16:56
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Published : International Journal of Medicine and Public Health, Vol 7, Issue 1, Jan-Mar, 2017 Pages:56-60.
DOI:10.5530/ijmedph.2017.1.10 ;Published:February 2017
Type:Original Article

Balajee Karthik L1, Babu Sujith1, Suliankatchi Rizwan A2, Meena Sehgal3Balajee Karthik L1, Babu Sujith1, Suliankatchi Rizwan A2, Meena Sehgal3
1Department of Preventive and Social Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India
2Department of Community Medicine, Velammal Medical College Hospital & Research Institute, Tamil Nadu, India
3Centre for Environmental Studies, The Energy and Resources Institute, New Delhi, India
*“These authors contributed equally to this work.”

ABSTRACT

Surface level ozone is one of the important air pollutants. It is formed by the reaction of atmospheric pollutants in the presence of sunlight. The surface ozone shows temporal and spatial variations in the country. The levels are maximum during summer and minimum in monsoon seasons. The levels are maximum during daytime and minimum during night or early morning. In India, surface ozone levels are above the recommended threshold of 8 hour average of 100 μg/m3 for air quality monitoring at various stations. Exposure to high levels of surface ozone causes number of health problems. Short term exposure causes drop in lung function measures and it also affects the lung’s mucociliary function thereby increasing the susceptibility to bacterial infections. With increase in surface ozone levels, there is likelihood of an increase in risk of hospital admissions for Chronic Obstructive Pulmonary Diseases (COPD) and the number of cardiovascular and respiratory deaths. In children, increase in ozone concentration is associated with increase in hospital admissions and unscheduled asthma medications. The high levels of surface ozone are becoming a threat to people’s health and so surface ozone levels have to be monitored and steps taken to reduce their levels.

Key words: Surface Ozone, Pollution, Respiratory, Cardiovascular Diseases, India

Key Messages: Surface level ozone is an important air pollutant causing cardiovascular and respiratory diseases. The levels are above the recommended threshold at various stations in India. Surface ozone has to be monitored and steps taken to reduce their levels.

Submission Date: 10-10-2016 Revision Date: 05-01-2017
Accepted Date: 06-01-2017

DOI : 10.5530/ijmedph.2017.1.10


INTRODUCTION

Outdoor air pollution is a major environmental health problem. Exposure to air pollution leads to increased risk of respiratory diseases like acute respiratory infections and chronic obstructive pulmonary diseases; and cardiovascular diseases, such as stroke and ischemic heart disease. According to World Health Organization, one in eight total global deaths occurs as a result of exposure to air pollution.1World Health Organization.Burden of disease from ambient air pollution for 2012. [Internet]. Geneva, Public Health, Social and Environmental Determinants of Health Department, World Health Organization, Available from: http://www.who.int/phe/health_topics/outdoorair/databases/AAP_BoD_results_March2014.pdf?ua=1 Over 3.5 million people die each year from outdoor air pollution. Low- and middle-income countries, especially the Western Pacific and South-East Asian countries account for about 88% of those premature deaths.1World Health Organization.Burden of disease from ambient air pollution for 2012. [Internet]. Geneva, Public Health, Social and Environmental Determinants of Health Department, World Health Organization, Available from: http://www.who.int/phe/health_topics/outdoorair/databases/AAP_BoD_results_March2014.pdf?ua=1 According to a recent study by the Organization for Economic Co-Operation and Development (OECD), in India, the cost of air pollution to society in 2010 was estimated at US$ 0.5 trillion.2OECD (2014), The Cost of Air Pollution: Health Impacts of Road Transport, OECD Publishing, Paris. Available from: http://dx.doi.org/10.1787/9789264210448-en. Ozone is one of the air pollutants of major concern globally. Higher levels of ozone in the air can affect human health, leading to breathing problems, asthma exacerbation and reduced lung function. Several studies have also shown that daily mortality and heart diseases increase with exposure to high levels of ozone.

MATERIALS AND METHODS

Literature search was carried out in PubMed, WHO website and Google Scholar. Inclusion criteria used were: articles published from 1980 to 2014 concerning ozone and its health effects with special reference to India, in any language and of any design. Articles on ozone layer and ozone depletion were excluded. Cross-references of articles included in the review were also searched. Key words used during the search were surface ozone, health effects, air pollution, mortality, morbidity, seasonal variations and ozone standards. All relevant articles were critically analysed and the contents were extracted into broad thematic areas for further interpretation.

RESULTS AND DISCUSSION

During the search a total of 55 relevant articles were identified and analysed. The results are presented below in the pre-identified thematic areas.

Ozone

Ozone is a colorless gas composed of three atoms of oxygen. It occurs both in the Earth’s upper atmosphere and at ground level. The ozone layer occurs naturally in the upper atmosphere (the stratosphere), 6 to 30 miles above the Earth’s surface. This protective ozone layer shields the Earth from the sun’s ultraviolet rays. But manmade chemicals are gradually destroying this layer, resulting in a “hole in the ozone” over the north and south poles. The tropospheric or ground level ozone lies in the Earth’s lower atmosphere is an important photochemical pollutant. This surface ozone (O3) is formed when pollutants like as Volatile Organic Compounds (VOCs) and oxides of nitrogen chemically react in the presence of sunlight. As a result, the highest levels of ozone pollution occur during periods of sunny weather. Cars, power plants, industrial boilers, refineries, chemical plants, and other sources emit these pollutants. Once formed, ozone is scavenged by NO and a “photo stationary state” is formed where concentrations of NO, NO2 and O3 are all inter-related. But the presence of CO and VOCs can disturb this steady state relationship by producing peroxy radicals and resulting in an increased ozone concentration.3Tang L. Regional and Local Surface Ozone Variations in Relation to Meteorological Conditions in Sweden [dissertation on the Internet] Gothenburg, University of Gothenburg, 2009. Available from: https://gupea.ub.gu.se/bitstream/2077/20200/1/gupea_2077_20200_1.pdf.

Due to the worldwide increase in the burning of fossil fuels, atmospheric CO2 concentrations are currently rising at approximately 0.5% per year and surface ozone values are increasing at a rate of 0.32% per year.4Akram A. Ali, Ibrahim A. Hassan and Hanaa S. Fahmi, 2002. Uncertainties in Estimating Ecological Effects of Ozone under Egyptian Climatic Changes . Journal of Biological Sciences, 2: 560-564, Available from: https://doi.org/10.3923/jbs.2002.560.564. Ozone can be transported over long distances by wind and due to this even rural areas can experience high ozone levels. High ozone concentrations have also been observed in cold months, with high levels of local VOC and NO emissions. Smog is primarily made up of ground level ozone combined with other gases and particle pollution. Surface ozone is also a greenhouse gas which contributes to climate change.

Characteristics of ozone pollution

Factors influencing ozone concentration

Many meteorological factors influence ozone concentration. Solar irradiation and temperature influence the speed and amount of photochemical production of ozone. Vertical temperature gradient influences the vertical mixing in the atmosphere and thereafter the ozone concentration near the ground. Surface winds control the concentrations in mountain valleys and coastal areas. Aloft winds are responsible for the transport of ozone and its precursors. Precipitation decreases the ozone concentration by means of wet deposition. Relative humidity chemically controls the ozone concentration and diurnal meteorological variations cause diurnal variation of ozone concentrations.

Ozone Guidelines

In 1997, the United States Environmental Protection Agency (EPA) proposed adding an ozone standard of 80 ppb based on the daily 8-hour maximum concentration. WHO Air Quality Guidelines for Europe (WHO AQG, 2000) had set the guideline value for ozone levels at 120 μg/m3 for an 8-hour daily average. But studies have shown health effects at concentrations below 120 μg/m3. So WHO Air Quality Guidelines AQG in 2005 reduced the cut-off from 120 μg/m3 to 100 μg/m3 (daily maximum 8-hour mean).5World Health Organization. WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide: global update 2005: summary of risk assessment. Geneva World Heal Organ [Internet]. 2006;1–22. Available from: http://whqlibdoc.who.int/hq/2006/WHO_SDE_PHE_OEH_06.02_eng.pdf?ua=1. In the year 2009, for the first time, India included ozone under its Revised National Ambient Air Quality Standards (NAAQS).6Central Pollution Control Board, National Ambient Air Quality Status 2009, Central Pollution Control Board, Ministry of Environment & Forests 2011 Available at: http://cpcb.nic.in/upload/Publications/Publication_514airquality status 2009.pdf According to this, the mean concentration of ozone in ambient air must be less than 100 μg/m3 for any 8 hour period of monitoring and less than 180 μg/m3 in hourly monitoring. This should be complied with 98% of the time in a year and in 2% of the time, they may exceed the limits but not on two consecutive days of monitoring.7Central Pollution Control Board, National Ambient Air Quality Status & Trends In India-2010 Central Pollution Control Board. 2012.

Variations in Ozone level

The ground level ozone levels are not constant. It varies from country to country and even within a country varies from region to region. Monthly measurements at 50 stations in Asia, Africa, South America, and Europe showed that the median ozone concentrations were maximum at Waliguan Mountain, China (45ppb) and minimum at Petit Saut, French Guiana (8ppb). The highest ozone values were found in the mid-latitudes, with Northern hemisphere values exceeding the Southern hemisphere levels, and the lowest values found in the tropical regions.8Carmichael GR, Ferm M, Thongboonchoo N, Woo JH, Chan LY, Murano K, et al. Measurements of sulfur dioxide, ozone and ammonia concentrations in Asia, Africa, and South America using passive samplers. Atmos Environ. 2003;37(9-10):1293–308. https://doi.org/10.1016/S1352-2310(02)01009-9. In India, in addition to regional variation, ozone shows diurnal (or daily) and seasonal variations as shown in Table 1 The ground-level ozone is maximum during summer and minimum during monsoon seasons. In most parts of the country, the levels are maximum either during daytime or noon and minimum during night time or early morning.


Table 1: Characteristics of ground level ozone in India


Highest ozone levels in India

In India, the highest level of ground level ozone has been reported in number of individual studies. But the regional variations of ozone are difficult to document as these studies are done at different stations in varying time points and have used different measures to report the highest level. Still in many locations the 8 hourly ozone levels exceeded the recommended 100 μg/m3 as shown in Table 2.

Health effects of Ozone: global literature

Pathological and functional changes in the lung

Ozone has been shown to alter epithelial permeability of the lung after 18-20 hours of exposure.38Foster WM, Stetkiewicz PT. Regional clearance of solute from the respiratory epithelia: 18-20 h postexposure to ozone. J Appl Physiol [Internet]. 1;81(3):1143–9. The lung’s mucociliary function is also acutely stimulated by ozone.39Foster WM, Costa DL, Langenback EG. Ozone exposure alters tracheobronchial mucociliary function in humans. J Appl Physiol. 1;63(3):996–1002. These effects can increase susceptibility to bacterial respiratory infections. Exposure to ambient levels of ozone for 6.6 hours has been shown to increase the markers of inflammation like the Neutrophils (PMNs), Prostaglandin E2 (PGE2), fibronectin, Interleukin-6 (IL-6), and Lactate Dehydrogenase (LDH), alpha-1 antitrypsin in the lungs, and decrease phagocytosis via the complement receptor.40Devlin RB, McDonnell WF, Mann R, Becker S, House DE, Schreinemachers D, et al. Exposure of humans to ambient levels of ozone for 6.6 hours causes cellular and biochemical changes in the lung. Am J Respir Cell Mol Biol [Internet]. 1991 Jan [cited 2015 Jan 31];4(1):72–81. Available from: http://www.ncbi.nlm.nih.gov/pubmed/1846079. Short-term exposures to ambient-level O3 concentrations cause drop in lung function measures such as lung volume and expiratory flow rates, forced vital capacity and specific airway conductance.41Kinney PL, Thurston GD, Raizenne M. The effects of ambient ozone on lung function in children: a reanalysis of six summer camp studies. Environ Health Perspect. 1996;104(2):170–174. https://doi.org/10.2307/3432785: https://doi.org/10.1289/ehp.96104170; PMid:8820584 PMCid:PMC1469279. The APHEA (Air Pollution and Health, a European Approach) project in 1997 by Andersen et al in 6 European cities showed there was an increase in hospital admissions for Chronic Obstructive Pulmonary Diseases (COPD ) for all ages for a 50 μ/m3 change in ozone (RR=1.04).42Andersen HR, Spix C, Medina S, Schouten JP, Castellsague J, Rossi G, et al. Air pollution and daily admissions for chronic obstructive pulmonary disease in 6 European cities: Results from the APHEA project. Eur Respir J. 1997;10:1064-71. https://doi.org/10.1183/09031936.97.10051064.


Table 2: Highest ozone level recorded at various stations in India


Note:

#The level of ozone is expressed as μg/m3 by multiplying ppb by a factor of 2

*Accumulated exposure over a cut-off threshold of 40 ppb

^Mixing ratio is defined as the ratio of the number of molecules of a particular trace gas to the number of molecules of all the other gases present in a given volume of air

Mortality

A meta-analysis of time series studies and panel studies by WHO in 2004 showed that there was a 0.44% increase in daily mortality per 10 ppb change in 1-hour maximum ozone concentration.43Anderson H, Atkinson R, Peacock J, Marston L, Konstantinou K. Meta-analysis of time-series studies and panel studies of particulate matter (PM) and ozone (O3). Rep a WHO Task Gr [Internet]. 2004;1–68. Available from: http://scholar.google.com/scholar?hl=en&btnG=Search&q=intitle:Meta-analysis+of+timeseries+studies+and+panel+studies+of+Particulate+Matter+(+PM+)+and+Ozone+(+O+3+)#0 Similarly a meta-analysis of 50 time-series analyses by Levy et al in 2001 showed a 0.39% change in daily mortality per 10 ppb change in daily 1-hour maximum ozone.44Levy JI, Carrothers TJ, Tuomisto JT, Hammitt JK, Evans JS. Assessing the public health benefits of reduced ozone concentrations. Environ Health Perspect [Internet]. 2001 Dec [cited 2015 Jan 31];109(12):1215-26. Available from: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1240503&tool=pmcentrez&rendertype=abstract The APHEA project in 15 European cities by Touloumi et al in 1997 showed that increases of 50 μg/m3 in O3 (1-hour maximum) was associated with a 2.9% increase in the daily number of deaths.45Touloumi G, Katsouyanni K, Zmirou D, Schwartz J, Spix C, de Leon a P, et al. Short-term effects of ambient oxidant exposure on mortality: a combined analysis within the APHEA project. Air Pollution and Health: a European Approach. Am J Epidemiol. 1997;146(2):177-85. https://doi.org/10.1093/oxfordjournals.aje.a009249; PMid:9230780. The APHEA 2 project by Gryparis et al in 23 cities/areas for 3 years since 1990 showed that an increase in 1-hour ozone concentration by 10 μg/m3 was associated with a 0.33% increase in the daily number of deaths, 0.45% in the number of cardiovascular deaths, and 1.13% in the number of respiratory deaths.46Gryparis A, Forsberg B, Katsouyanni K, Analitis A, Touloumi G, Schwartz J, et al. Acute effects of ozone on mortality from the “Air Pollution and Health: A European Approach” project. Am J Respir Crit Care Med. 2004;170(30):1080–7. https://doi.org/10.1164/rccm.200403-333OC; PMid:15282198.

Child health

Young children are sensitive to O3, because significant lung development continues in the postnatal period.47Finkelstein JN, Johnston CJ. Enhanced sensitivity of the postnatal lung to environmental insults and oxidant stress. Pediatrics. 2004;113(4):1092–6. PMid:15060204. Burnett et al demonstrated that in children under 2 years of age, there was a 6.6% increase in hospital admissions per 10 ppb change in 1-hour daily maximum ozone (RR = 1.348).48Burnett RT, Smith-Doiron M, Stieb D, Raizenne ME, Brook JR, Dales RE, et al. Association between ozone and hospitalization for acute respiratory diseases in children less than 2 years of age. Am J Epidemiol. 2001;153(5):444–52. https://doi.org/10.1093/aje/153.5.444; PMid:11226976. Thurston et al showed that among children aged 7 to 13 years in summer asthma camps in New York City, an increase in the 1-hour daily maximal ozone concentration from 84 to 160 ppb was associated with increased unscheduled medications administered per day.49Thurston GD, Lippmann M, Scott MB, Fine JM. Summertime haze air pollution and children with asthma. Am J Respir Crit Care Med [Internet]. American Public Health Association; 1997 Mar 20 [cited 2015 Jan 31];155(2):654–60. Available from: http://www.atsjournals.org/doi/abs/10.1164/ajrccm.155.2.9032209#.VMz9-ELlNv0. The health effects of ozone are summarised in Table 3.

Health effects of Ozone: Indian literature

Studies on health effects of ozone from India are limited. Gupta et al demonstrated a significant increase in daily hospital admission for respiratory diseases with elevated levels of ozone.50Gupta S, Dogra T.D. Air pollution and human health hazards [Internet]. Indian Journal of Occupational and Environmental Medicine. Medknow Publications and Media Pvt. Ltd (B9, Kanara Business Centre, off Link Road, Ghatkopar (E), Mumbai 400 075, India); 2002. p. 89–93. Available from: http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=emed5&NEWS=N&AN=2002329540. Kumar et al conducted a cross-sectional study in Punjab and showed that levels of ozone were found to be higher in an industrial town than in the a non-industrial town and that residence in the industrial town was associated with increased chronic respiratory symptoms like cough, phlegm, breathlessness, or wheezing (OR= 1.5) and spirometric ventilatory defect (OR = 2.4).51Kumar R, Sharma M, Srivastva A, Thakur JS, Jindal SK, Parwana HK. Association of outdoor air pollution with chronic respiratory morbidity in an industrial town in northern India. Arch Environ Health. 2004;59(9):471–7. https://doi.org/10.1080/00039890409603428 ; PMid:16381489. Jayaraman et al in Delhi showed that a 10-microgram rise in O3 led to increase in respiratory morbidity (RR = 1.03).52Jayaraman G, Nidhi. Air pollution and associated respiratory morbidity in Delhi. Health Care Manag Sci. 2008;11(2):132-8. https://doi.org/10.1007/s10729-007-9050-7; PMid:18581819.

Control of ozone pollution

Through global climate policies, it is estimated that in the time horizon up to 2050, a decrease of ozone concentrations might save nearly 20,000 cases of premature death per year.53Rafaj P, Schöpp W, Russ P, Heyes C, Amann M. Co-benefits of post-2012 global climate mitigation policies. Mitig Adapt Strateg Glob Chang. 2013;18(6):801-24. https://doi.org/10.1007/s11027-012-9390-6. The annual monetary value of health benefits from reducing ozone concentration was estimated to be $10 per person per microgram per cubic meter reduction.44Levy JI, Carrothers TJ, Tuomisto JT, Hammitt JK, Evans JS. Assessing the public health benefits of reduced ozone concentrations. Environ Health Perspect [Internet]. 2001 Dec [cited 2015 Jan 31];109(12):1215-26. Available from: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1240503&tool=pmcentrez&rendertype=abstract Steps that are needed to reduce ground-level ozone are as follows:

Legal framework and monitoring of Ozone levels

In India, National Air Quality Monitoring Program (NAMP) is a nationwide program executed by Central Pollution Control Board (CPCB) to monitor the ambient air quality through a network of over 340 stations across the country. Under NAMP, only four air pollutants namely Sulphur dioxide (SO2), Oxides of Nitrogen, Suspended Particulate Matter (SPM) and Respirable Particulate Matter (RSPM) are regularly monitored.54Central Polution Control Board,Air/Quality Pollution , NAMP [Internet]. [cited 2015 May 18]. Available from: http://www.cpcb.nic.in/air.php. Surface ozone is regularly monitored by the CPCB through automatic monitoring stations in New Delhi and few other stations. Nevertheless, surface ozone level must also be regularly monitored throughout the country and particularly in rural neighborhoods surrounding large cities as ozone levels are likely to be high in these neighborhoods, particularly because agriculture production is known to be adversely affected by high ozone concentrations.

Automobile manufacturing and auto fuel industry can introduce several measures to reduce emissions of precursor pollutants including Vapor Recovery Control, which are systems that control VOC vapour releases during the refuelling of motor vehicles, timely engine turnover, and adoption of cleaner and lower emitting new engines. Similarly, coal-burning power plants can adopt clean coal technology to reduce emissions. Urban planners and policy makers can support the cause through improving public transport, reduce congestion on roads, reduce idling time and incentivize use of hybrid or electric vehicles.


Table 3: Health effects of increased surface ozone


To reduce vehicular pollution, Honorable Supreme Court of India has ordered the states to strictly implement Emission Norms and to switch over to clean fuels like Compressed Natural Gas (CNG) and Liquefied Petroleum Gas (LPG). Emission standards for the industries are notified under Environment (Protection Act) 1986 to check pollution. The states have given an action plan to the Supreme Court, in which they have given commitment to monitor that the industries are using cleaner fuel, developing green belt and installing pollution control devices.

Role of individuals and NGOs in controlling Ozone level

The public can also reduce ozone levels by conserving energy at home and at work; by reducing vehicle by walking, cycling or using public transportation whenever possible, following gasoline-refueling instructions, keeping motor vehicle engines properly tuned and making sure that tires are properly inflated.55US EPA. Actions You Can Take to Reduce Air Pollution Ground-level Ozone. New England. US EPA [Internet]. [cited 2015 May 18]. Available from: http://www.epa.gov/region1/airquality/reducepollution.html.

Conclusions

The ground level ozone measured at various stations across the country exceed the threshold limit. Ground level ozone is a health hazard – leading to respiratory and cardio vascular diseases and their exacerbations and adding to the cost of health care of an already strained health system. Policy changes are required to reduce the generation of ground-level ozone and to monitor the ambient levels and health effects. Further studies have to be conducted to measure the mortality and morbidity due to this pollutant in India and the cost of inaction.

Conflict of interest

None

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