Date of Award

1-1-2023

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Environmental Health Sciences

Content Description

1 online resource (xxix, 420 pages) : illustrations (some color)

Dissertation/Thesis Chair

Haider A Khwaja

Committee Members

Gary Ginsberg, Insaf Tabassum, Xianliang Zhou, David O Carpenter

Keywords

Air pollution, Karachi, PM2.5, PM2.5 constituents, Southeast Asia, Urban air pollution, Air, Particulate matter, Lungs

Subject Categories

Public Health

Abstract

Globally, air pollution has a negative impact on public health due to the continuous use of fossil fuel to power industries, industrial emissions, vehicular emissions, open burning of garbage waste and exposure to fine particulate matter (PM2.5), which is linked to an increase of various diseases as well as an excess of morbidity and mortality. Although air pollution affects every nation, developing countries face unique challenges. There is a dire need to reduce air pollution in developing countries, with the World Health Organization (WHO) reporting that large cities in low- and middle-income countries have exceptionally high levels of air pollution. Additionally, most air pollution-related deaths are recorded in developing countries, where laws are lax or not enforced, vehicle emission standards are lax and an increase in industrial activity leading to factory emissions from coal-powered steam engines and burning of fossil fuels which release hazardous chemicals into the atmosphere has contributed to air pollution. Take Pakistan, one of the most polluted nations in the world and relies heavily on the use of fossil fuels. The average Pakistani's life expectancy is shortened by 60 months because of air pollution, relative to what it would have been if the WHO guidelines were met. While many studies have shown evidence of increased morbidity and mortality of lung cancer, asthma, Chronic obstructive pulmonary disease (COPD), and reduced lung function with long term exposure to fine particulate matter (PM2.5), the sources and effects of short-term exposure to PM2.5 needs to be better assessed in Karachi, Pakistan. There is severe air pollution in major cities of Pakistan and limited information is available. Little is known about the extent and impact of environmental pollutants on human health for the megacity, Karachi. Furthermore, air pollution studies and impact on health in urban cities of developing countries of Asia needs to be investigated further. Keeping this in view, the current study was designed to investigate the air quality in Karachi using time-series analysis over a period of four seasons (fall, winter, spring, and summer). And assessed association between exposure to daily concentrations of air pollution and pulmonary morbidities. Using daily PM2.5 levels seasonally from the sampling sites AQI proportion was calculated to measure the quality of the air. Pearson correlation was used to show the intercorrelation between PM2.5, BC, trace elements, ionic species, and meteorological parameters. Enrichment factor (EF) analysis was utilized to identify heavy metals in PM aerosols according to natural and anthropogenic sources. Positive matrix factorization (PMF) to determine source apportionment and backward-in-time trajectories to investigate local and long-range pollutant emissions. Analysis of samples for anions and cations was performed as well as black carbon (BC) from collected PM2.5 samples. Negative binomial generalized linear time-series (GLM) model was used to estimate the risk of pulmonary morbidity associated with exposure to gaseous pollutants, PM2.5, BC, and trace elements (TEs). The human health risk assessment of short-term PM2.5 exposure were calculated using the Risk Assessment Information System (RAIS). The measure of human health impact assessment for expected number of deaths and risk of exposure per 1000 people were estimated. Over the study period in Karachi, 12,592, 8,971, and 5,704 pulmonary morbidity records were collected in a three-year period, of which 5,259 (41.8%) were females and 7,333 (58.2%) males for the first year; 3,859 (43.5%) were females and 5,112 (57.0%) males for the second year; and 2,480 (43.5%) were females and 3,224 (56.5%) males for the third year. In the first year, there were 11,870 emergency room visits (ER) visits and 722 hospital admissions (HAs); the second year consisted of 5,104 ER visits and 3,867 HAs; and third year included 5,013 ER visits and 691 HAs. Based on daily exposures to air pollutants during the four seasons of the year, stratified single pollutant model analysis by age, gender, and town codes by single lag days (0-5) was performed. The model adjusted for the influence of meteorological factors, season, and day of the week. And the model fit was assessed with deviance and Pearson’s chi-square as a measure of the goodness of fit. PM2.5 concentrations were highest in the winter and lowest in the summer as shown in time-series analysis. The average annual PM2.5 concentrations observed at Malir and Kemari sampling sites were compared with WHO guidelines and studies conducted in metropolis centers in developing and developed countries globally. Annual average concentrations exceeded the WHO guideline (5 μg/m3) by factors of 19.0 and 28.0 at the Malir and Kemari sites, respectively. Additionally, >99% of the daily PM2.5 concentrations significantly exceeded the WHO 24-hr guideline (15 μg/m3) by a factor of 12 at the Kemari site and 9 times higher at the Malir site. BC levels exceeded the average levels for all seasons. The highest recorded BC concentration was 32.8 µg/m³ for Kemari and approximately 15 µg/m³ for Malir during the colder months (November – December). The sampling sites showed an influx of metal ions emitted by anthropogenic and natural sources. The most prevalent toxic metals were lead and nickel. Anion analysis showed chloride (Cl-), sulfate (SO4 2-), and nitrate (NO3 -) levels continued to rise. The cations analysis showed high calcium (Ca2+), sodium (Na+), and potassium (K+) levels. In general, the estimated relative risks (RR) indicated an increased risk for total pulmonary and subtypes at Lags 0 and 3-5 following exposure to ambient air pollutants. Males had the highest risk of COPD, while both sexes had an increased risk for asthma and shortness of breath (SOB). Tuberculosis (TB) and asthma were prevalent among patients aged 0-50, while COPD was prevalent among patients 51+. SOB was prevalent among both age groups. The prevalence of pulmonary morbidity due to pollutant exposure was greater among age group 0-50 and males in this study. Stratified analysis by age and gender indicated a notable increase in pulmonary morbidity associated with daily exposure to gaseous pollutant ozone (O3), sulfur dioxide (SO2), PM2.5, BC, and toxic metals like Pb, Ni, Cu, Cl, and S. Additionally, gaseous pollutants such as O3 that have limited epidemiological and toxicological studies supporting a causal relationship with pulmonary outcomes indicated morbidity risks in this study. This may be explained by Pakistan's relatively elevated levels of air pollution. Statistically significant associations were found between pollutants and pulmonary morbidities assessed mostly at delayed lag days. The study method used was a time-series analysis, and only information on the date of admission and primary diagnosis was attained. We couldn’t investigate events that occurred before or after patients’ hospital visits. Based on our findings, motor vehicle emissions, fossil fuel combustion, and sea salt and dust particles are the primary sources of PM2.5 and its constituents. Previous studies linked exposure to PM2.5 to development of oxidative stress, pulmonary inflammation, and several severe cardiac events. Particulate matter accounts for most of the air pollution in Karachi, Pakistan. Monitoring and assessing the daily PM2.5 constituent levels in Karachi were tied to the poor air quality. This is the first study in Pakistan to investigate the levels of air pollutants and their association between pulmonary diseases and PM2.5 constituents. The results of this study provide a useful insight into the possible health risks associated with exposure to elevated levels of air pollution. While previous studies have reported health risks associated with exposure to particulate air pollution based on much lower air pollution levels in developed countries in North America and Europe, most of the studies have been on air pollution and cardiovascular diseases. The levels of gaseous pollutants and PM2.5 in Karachi pose a threat for pulmonary morbidity risks among all age groups and gender. This highlights the detrimental effects of particulate air pollution on human health. Further studies in other urban cities of Pakistan are essential. Thus, to protect public health in Pakistan, it is urgent to develop a regulatory strategy to control fine particulate matter air pollution. Regulatory measures to reduce particulate emissions from these sources will help reduce air pollution levels in Pakistan's major cities.

Download

Included in

Public Health Commons

Share

COinS