Introduction

In the present ecological scenario of climate change and the increasing burden on natural resources, there are several environmental effects on global public health as well, as the environment affects human health in various ways. Researchers have proved in the past that ecological risks can significantly impact human health, either through direct or indirect means. It can directly impact human health by exposing humans to harmful agents. It can indirectly affect human health by disrupting ecosystems. We cannot precisely state how the environment contributes to the new emergence of diseases. However, the World Health Organization (WHO) has stated that around 13 million deaths worldwide per year are due to environmental causes that we could have easily avoided. The report by the WHO also states that 24% of diseases globally and 23% of deaths can be attributed to environmental factors.

Despite all we know about the environmental effects on global public health, environmental degradation continues. And the main reason for continued ecological destruction is increased population and economic growth. An increasing population increases the demand for food, energy, and products. Therefore the agricultural, industrial, and energy generation sectors need to expand to meet the rising demands. In developing countries, health impacts of environmental hazards are associated with poverty, lack of infrastructure and access to clean drinking water, sanitation, and proper health care. In the more developed and wealthier countries, environmental effects on health are mainly associated with air and water pollution. The number of cases of people developing asthma is rising in developed countries. Scientists warn that we could witness the emergence of new diseases and the increases in existing ones, such as malaria and cholera if we do not take urgent steps to protect our ecosystems.

Air Pollution

Air pollution causes severe environmental effects on global public health. Scientists estimate that air pollution is responsible for approximately 2 million premature deaths every year worldwide. Air pollution causes respiratory infections, lung cancer, stroke, pulmonary disease, pneumonia, and heart diseases. Some studies also link exposure to air pollution with an increased risk of adverse pregnancies, neurological disorders, and cognitive impairment.

Air pollution is essentially the presence of contaminants like fumes, dust, smoke, vapour, etc., in the air. When we breathe in these pollutants, the cells in our body develop inflammation, stress, and immunosuppression. It impacts our brain, heart, and lungs and ultimately leads to disease. Microscopic pollutants can travel via our bloodstream through the entire body. The penetration of contaminants into our bloodstream leads to inflammation of our systems and carcinogenicity.

Source: https://www.worldbank.org/en/country/india/publication/catalyzing-clean-air-in-india

Children, the elderly, and pregnant women are the population most susceptible to diseases related to air pollution. Nutrition, genetic, and socio-demographic factors also play a role in increasing or decreasing a person’s susceptibility to air pollution-related diseases.

Many toxins have disastrous effects on human health. However, the ones of most concern and that impact public health the most are carbon monoxide (CO), sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM). The various pollutants mentioned have different levels and duration of exposure considered ‘safe’. Long term exposure to particulate matter increases a person’s risk of developing non-communicable diseases such as cancer, pulmonary disease, heart disease, and stroke.

Water Pollution

Polluted water and poor sanitation are responsible for the transmission of diseases like polio, typhoid, hepatitis A, diarrhoea, cholera, and dysentery. Inadequate or mismanagement of water resources can expose people to unnecessary health risks.

The improper handling and management of agricultural and industrial wastewater mean that the drinking water of hundreds of people is at a risk of getting contaminated and chemically polluted. The presence of natural chemicals such as fluoride in water, especially groundwater, plays a significant role in maintaining our health. However, some other chemicals like lead may leach into our drinking water supply from the pipes or plumbing that transports water to our taps. Lead is hazardous to human health.

The WHO estimates that around 8,29,000 people die every year due to diarrhoea. People develop diarrhoea from consuming unsafe drinking water and lack of sanitation and hygiene. Apart from this, even insects that live and breed in water bodies can transmit diseases such as dengue fever when humans consume such water.

Water quality and safety are of utmost importance to the well-being of humans. The most common sources of contaminants found in drinking water are:

1. Industry and agriculture:

Organic solvents, heavy metals, pesticides, and fertilizers

2. Human and animal waste:

Human and animal waste sewage and septic systems placed in the vicinity of a drinking water source can contaminate the source. The major contaminants include E. coli, cryptosporidium, and giardia.

3. Natural sources:

Some naturally occurring sources of water are simply unfit for consumption. For example, as groundwater travels and percolates through soil and rocks, it can pick up natural arsenic, radionuclides, and other heavy metals. This water is not suitable for drinking.

Climate Change

Climate change is currently the single biggest threat to human health. The International Panel on Climate Change (IPCC) has said that we must limit the Earth’s warming to 1.5 ^oC to avert the worst of climate change health impacts. However, even a rise in temperature of 1.5^oC is not safe. Every tenth of an increase in degree will take a severe and destructive toll on the health and lives of people. Climate change is causing the growth of food, water, and vector-borne diseases. The people affected most by climate change are those that contribute the least towards it. Health risks associated with climate change are felt by the most disadvantaged populations, including women, children, migrants, ethnic minorities, the elderly, and those with underlying health conditions.

We can already feel the impact of climate change on public health in various ways. It has caused death, illness, and mental health issues among people. Although scientists are confident that climate change affects public health, they cannot estimate the scale and impact of the health risks associated with climate change. However, we can determine the effects of climate change by the vulnerability of specific populations and their resilience and rate of adaptation. Climate change’s environmental effects on global public health will also depend on how much action we take right now to reduce emissions and avoid crossing the temperature thresholds.