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How Environmental Changes Affect Human Health?

With the increasing pace of commercialization and modernization in the century, the environmental changes are threatening human health significantly. The most counted climatic changes include increased temperatures, changes in precipitation, increased possibilities of extreme weather, and rising sea levels. These environmental changes are worsening human health by affecting the food we eat, the water we drink, the air we breathe, and most importantly, the weather we experience.

The level of impact on human health due to these uncertain environment changes depends upon two significant circumstances:

  • The capability of public health and safety systems to address and manage the changing climates
  • Most importantly, an individual’s genetic makeup, age, gender, behaviour, and economic status

No reports claim that only the people living in developing countries or children, pregnant ladies, elders, or lower-income populations are at risk of a threat to health. Climate changes are posing significant threats to the health of people living in wealthy nations such as the United States as well.

In the following article, you will study how human health is affected by different environmental changes such as warming temperatures, poor air quality, increased precipitation and humidity, and extreme weather events. The second section of the paper deals with the number of illnesses promoted with these environmental changes.

How food safety and nutrition are at risk due to extreme weather events is also a part of this section. The article is concluded with the suggestion of a few preventive actions, especially for the healthcare sector.

Section-1 Impact of Individual Environmental Changes on Human Health

Impact of Warming Temperatures on Human Health

The summers bring hotter days and more frequent and longer heatwaves. The warming average temperatures are increasing heat-related deaths, especially in the US. There, the death count is speeding significantly from thousands to tens of thousands every year during summer months. However, adaptive responses, such as increased use of air conditioners, are expected to reduce the death rate due to extreme heats.

Apart from cardiovascular, respiratory, and cerebrovascular disorders, exposures to extreme heats can lead to heat strokes and dehydration. The particular class of people who are vulnerable to the warming temperatures are:

  • People living in northern latitudes are less prepared to cope with excessive temperature
  • Outdoor workers, student-athletes, and homeless people are more prone to hot waves due to their maximum time spent in open fields
  • Low-income families may also have increased exposure to hotness due to their lack of access to air conditioning

Younger kids, pregnant ladies, elders, and people with certain medical conditions are more vulnerable to extreme heat due to their less ability to regulate body temperature. Due to impaired physiological responses of old age people during hot waves, they are unable to meet optimum cardiac output. Also, the decreased efficiency of sweating and the consumption of several medications in the advanced age makes them more prone to heatstroke.

Several reports claim that urban areas are found to be warmer than their rural surroundings. Due to this reason only, the death rates are notably high in the large metropolitan cities of the US such as St. Louis, Philadelphia, Chicago, and Cincinnati during the tropical waves. The threshold temperature for deaths in New York is 92 deg.F; above this temperature, the mortality rate increases dramatically.

A study was conducted to measure the heat factors associated with an increased rate of heatstroke. The results of the study concluded alcoholism, living on higher floors of buildings, and the use of tranquilisers as the prominent factors for increased risk of heatstroke. In contrast, the use of air conditioning, frequent exercising, consumption of fluids, and living in properly shaded homes were accountable for decreased risk of heatstroke.

Acclimatization- Usually, the death rate reduces significantly during the second heatwave despite the fact if the second heat is unusually extreme. Two possible explanations for this phenomenon can be provided:

  • Weaker and susceptible members of the community may die in the early hot waves of the summer
  • The survived population from the first heat waves become physiologically acclimatized and hence, can deal more effectively with more tropical waves.

Studies suggest that geographical acclimatization is sufficient proof for observing the relationship between warming temperatures and death rates. People moving from a cool to a subtropical climate will adopt the changes more rapidly, often within two weeks.

Impact of Air Quality on Human Health

Warming temperatures and rapid shifts in the weather patterns worsen the air quality. The degradation in air quality increases the risk of asthma and other respiratory and cardiovascular disorders. The severe climatic changes are promoting the frequency and severity of wildfires making climate prone to smoke and unhealthy air pollutants.

Increased Ozone Levels

  • The drastic environmental changes are increasing unhealthy levels of ground-level ozone, harmful air pollutants, and smog.
  • People who are exposed to higher levels of ground-level ozone are at a greater risk of dying prematurely.
  • Ground-level ozone is highly responsible for damaging lung tissue, reducing lung functioning, or inflaming airways. It can aggravate asthma or other lungs diseases.
  • The warm, stagnant air promotes the formation of ozone, and therefore, the environmental changes are increasing number of days with poor air quality.

Changes in Particulate Matter

Particulate matters are the very fine particles smaller than 2.5 micrometres (about one ten-thousandth of an inch) which remain suspended in the atmosphere. These tiny particles or liquid droplets can be dust, wildfire smoke, or sea spray.

Inhaling of the particulate matters can cause a wide range of adverse health effects, such as lung cancer, chronic obstructive pulmonary disease (COPD), and heart diseases
Fine particles produced from the wildfire smoke may often be carried out to very long distances by winds, affecting people who are far away from the source of air pollutant

Impact of Extreme Weather Events on Human Health

The extreme weather events defined as extreme precipitation, flooding, droughts, and storms threaten the health of people during and after the event. The possible ways in extreme weather events can impact human health are:

  • Reducing the access to food and availability of safe drinking water.
  • Disrupted access to hospitals and pharmacies due to damaged roads and bridges.
  • Interrupting communication, utility, and healthcare services.
  • The inadequate use of portable electric generators during and after the storms contributes towards the carbon monoxide poisoning.
  • Increased stomach and intestinal problems.
  • Mental health impacts such as depression and post-traumatic stress disorder (PTSD).

Impact of Humidity and Precipitation on Human Health

Effect of Humidity

The effect of humidity on mortality rate is very crucial. The impact of moisture decides the ability of the body to cool itself using evaporation through perspiration. The atmospheric moisture content determines human comfort.

The effect of low humidity is especially severe in winters. During cold weather when the moisture content is very low in the atmosphere, dry air passes through the nasal-pharynx and trachea, warming occurs there, and the air temperature rises to 30 deg.F in these organs. The capacity of the warmer air to hold the moisture in the pharynx causes the increased viscosity of bronchial mucus. At this stage, the microbial or viral attack is straightforward since the ability of the body to fight microorganisms is reduced due to the mucous present in the upper respiratory tract.

In the summer, when the moisture content is very high, the body’s ability to evaporate through sweat is reduced, which can lead to heat stress. Several weather/ mortality models developed for the National Oceanic and Atmospheric Administration indicate that when temperatures are sweltering, dew point temperature can be directly related to the mortality rate, especially in several eastern cities.

Effects of Precipitation

Extreme weather events in the form of precipitation can be directly connected to the mortality rates. During cold weather, the impact of snow can be statistically related to deaths due to stroke or heart attacks. Several studies report a marked increase in fatalities after three to five days of storms due to myocardial infarction.

A study was conducted to determine threshold values of accumulated snow above which the mortality rates are predicted to rise. In New York, two or more inches of snow accumulation just after one day of snowfall could be reported to show trends in mortality upwards. In Detroit, where snowfall is quite common, death rates appeared to exceed with the six inches of accumulation of snow. In Toronto, a four-inch or higher snow accumulation could be related to the increased ischemic heart diseases.

In contrast, summer rainfalls appear to show a limited impact on mortality.

Section-2 Human Health at Risk Due to Environmental Changes

2.1 Vector-Borne Diseases

The diseases caused by the transmission of infectious pathogens like viruses, bacteria, and protozoa by vectors (mosquitoes, ticks, or fleas) are called vector-borne diseases. Changes in temperature, precipitation, and extreme weather events are increasing the geographical range of diseases spread by vectors.

Temperature limits the geographical range of ticks that carry Lyme disease. An increase in temperature makes the ticks active earlier in the season, and hence, expansion of spectrum will not be unexpected. Common symptoms of Lyme disease include fever, headache, fatigue, and prominent skin rashes.

Extreme temperature ranges such as too cold, hot, wet, or dry limits the location and number of mosquitoes that carry the West Nile virus. In 1999-2010, more than three million people were found to be infected with West Nile virus in the United States

2.2 Water-related Illnesses

The environmental changes can increase the exposure towards waterborne pathogens (bacteria, viruses, and parasites such as Cryptosporidium and Giardia), harmful algae and cyanobacterial blooms responsible for producing toxins in water, and most prominently the chemicals leached in rivers by humans

The irregular changes in water temperatures promote the survival of waterborne Vibrio bacteria and harmful algal toxins in the water or seafood

Floods, precipitation, hurricane rainfall, and storms due to the environmental changes are contaminating the water bodies (lakes and beaches), and hence, making water unsafe for drinking

Several regulatory bodies such as water resources, public health, and environmental changes in different countries are providing measures for safeguarding public health. Reducing the risk of exposure and illness, even if the water is contaminated is their primary concern. The safeguards include water quality monitoring, drinking water standards, and practices, beach closures, and issuing advisories for safe practices.

2.3 Food Safety and Nutrition

Environmental changes are directly responsible for increased concentrations of carbon dioxide in the atmosphere, which is expected to affect food safety and nutrition.

The higher temperatures promote the Salmonella and other bacteria-caused food poisonings. Bacteria grow more rapidly in the warming temperatures. The effects of food poisoning caused by these environmental changes can not be limited to gastrointestinal stresses; several deaths have also been reported

Higher sea surface temperatures as an effect of environmental changes can lead to higher mercury concentrations in the seafood.

A higher concentration of carbon dioxide in the atmosphere is exceptionally responsible for lowering the protein levels and essential minerals in several crops such as wheat, rice, potatoes, and hence, making food less nutritious

Weather events such as floods or droughts can challenge the food distribution due to the damaged roads and waterways.

Section-3 Preventive Measures

Adapting strategies can minimize the effects of climate change, but the more exceptional approach for the public health systems should be to prevent environmental changes. Strict and fair policies at national and international levels are required for these preventive challenges.

Scientists have suggested various measures, out of which the most important is preventing the increase in the concentration of carbon dioxide in the atmosphere. The level of the gas shall not exceed 450-500 ppm to avoid irreversible damages to the natural systems and ecological processes. A global average increase in the temperature of 2-3 degC can cause the level to exceed the threshold value soon. Early radical action is just as today’s concentrations are approaching 390 ppm (compared with 280 ppm before industrialization). Health professionals have both the opportunity and responsibility to contribute to resolving this upcoming threat of life. Increasing awareness should be their first step. Since 1993, several doctors from fourteen countries (involving six low-income countries) have contributed their efforts by playing a central role in the Intergovernmental Panel on Climate Change’s assessment of the health effects of the environmental changes.

The health sector should promote the minimized emission of greenhouse gas from hospitals. Scientists and researchers are expected to reduce greenhouse gas emissions during their studies.


The unconstrained climate change is responsible for the potentiation of damage to the world’s economic system. However, the highest risk of environmental changes is to the vitality and health of all species, including humans. If the current trends continue to weaken the earth’s life support systems, the time of irreversible damage is not very far away. Health professionals can play a crucial role in spreading awareness of the drastic need for preventive actions towards these environmental changes.


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Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:February 18, 2022

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