Dr. Shyam P Lohani

Over last few days, the Kathmandu Valley has witnessed the worst air quality of recent times among cities in the world. Air Quality Index (AQI) in many parts of Kathmandu crossed its hazardous level for few days in the last week posing a serious threat to the health of the millions. The reasons for such a dangerous level of air quality in the valley are many and include mix of weather, vehicular emission, industrial pollution, and uncontrolled seasonal wildfires.
Air pollution is caused by the presence in the atmosphere of toxic substances, mainly produced by human activities such as vehicular emission, industrial activities and unplanned urbanisation. Oftentimes, natural disasters such as dust storms, volcanic eruptions and wildfires can also deteriorate the air quality.

Impact on health
A number of pollution-related diseases, including respiratory infections, heart disease, chronic obstructive pulmonary diseases (COPD), stroke and lung cancer, are increasing alarmingly worldwide, particularly in low- and middle-income countries. Air pollution has long been regarded as a silent killer responsible for causing a variety of chronic and acute conditions. Every year out of total 12.6 million deaths associated with unhealthy environment, air pollution is solely responsible for about 7 million deaths globally, a single largest environmental health risk (WHO, 2020). In fact, low- and middle-income countries are exposed to highest level of exposures and it has been estimated that 9 out of 10 people breathe unsafe air having high levels of toxic pollutants.
AQI is a measurement of the concentration of particulate matter below 10 and 2.5 microns, carbon monoxide, sulphur, nitrogen dioxide and ground ozone. AQI has been graded into different levels, between 0-50 is termed as ‘Good’, 51-100 is ‘Moderate’, 101-150 is ‘Unhealthy for Sensitive Groups’, 151-200 is ‘Unhealthy’, 201-300 is ‘Very Unhealthy’, and level above 301 is regarded as ‘Hazardous’.
The effects of poor air quality on human health are complex, but principally cause harm to the human respiratory and the cardiovascular system. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, and the health status of the individual and genetic predisposition.
Generated from poor quality roads, construction sites, and wildfires, particulate matter (PM 10) is the suspended particle of about 10 µm diameter which causes irritation to the eyes, nose, throat and are linked to acute respiratory illnesses. PM 2.5 (particles less than 2.5 µm in diameter) has the capacity to penetrate deep into the lung causing irritation and impairing lung function and even circulate through blood. Moreover, exposure to the PM 2.5 linked to decreased life expectancy.
Air pollution is composed of a complex mixture of thousands of pollutants, including airborne Particulate Matter (PM) and gaseous pollutants like ozone (O3), nitrogen dioxide (NO2), volatile organic compounds like benzene, carbon monoxide (CO), and sulfur dioxide (SO2), etc. The high concentration of carbon monoxide (CO) forms carboxyhemoglobin (COHb) and aggravates heart attack and also affects nervous system. On the other hand, NO2 causes bronchitis and bronchopneumonia while SO2 leads to eye irritation, conjunctivitis, and shortness of breath, chronic bronchitis, asthma, various heart diseases, lung disease, and cancer.
Ozone is associated with the development of cardiovascular and respiratory diseases. Benzene, can cause eye, skin, and lung irritation in the short-term while it causes blood disorders in the long-term. Affecting the liver in the short-term and harm the immune, nervous, and endocrine systems, as well as reproductive functions, Dioxins, found in polluted air, are harmful. Lead can damage children’s brains and kidneys in large amount, and even in small amount, it can affect development index of children and ability to learn. Mercury affects the central nervous system.
Polycyclic aromatic hydrocarbons (PAHs) are toxic components of traffic exhaust and wildfire smoke. In large amounts, they have been linked to eye and lung irritation, blood and liver diseases, and even cancer. Mothers with higher PAH exposure during pregnancy had children with slower brain processing speeds and worse symptoms of attention deficit hyperactivity disorder (ADHD). Air pollution is also associated with autoimmune diseases. Therefore, air pollution has been emerging as a major threat to the global public health.

Measures
Despite having several policies and guidelines on environmental issues, Nepal is yet to have its impact felt in terms of improvement in air quality and reduction of deleterious health effects due to air pollution. Long-term strategies such as renewable fuel and clean energy production, energy conservation and efficiency, ecofriendly transportation, and green building should be adopted and implemented strictly. Awareness about the impact of poor quality air to health has not yet reached the general public level. Therefore, large scale awareness campaigns against it and promotion of preventive measures should be carried out so as to control it from grassroots level.
The current situation of air pollution is a health emergency. It is the need of the hour to control wildfires in an efficient manner. Banning open burning, monitoring pollution producing industries, replacing old and malfunctioned vehicles, encouraging use of energy efficient equipment, and promoting use of renewable energy require continuous and long-term commitment from both the government and the responsible general public. During the time of hazardous level of air pollution, the general people are urged to stay inside their home with all the windows shut and limit their outdoor activities, including daily exercise.

(Professor Lohani is the founder and academic director at Nobel College. lohanis@gmail.com)