Morning walk is strongly recommended by both the health experts as well as many generalists owing to an age-old tradition, belief and actual accrued benefits. It is widely accepted that a person doesn’t need any special efforts or preparation in lieu of the accrued benefits for boosting physical and mental health in that it definitely improves heart function, assists to the body weight management, enhances mood, increases body energy and fitness as well good in regulation of the body rest and sleep. It is also held that these benefits are truly possible only when such a walk is done early before the daily distractions set in to interfere with other daily routines. When regularly done, it provides full-body reset, supports metabolism and circulation, and mental health through release of endorphins, which are better known as mood elevators and natural painkillers.

Why and how this author became a regular practitioner of this healthy routine is a story in itself dated as back as over four decades as of now. As a college student, he spent about nine years in the University of Lucknow staying in a boys’ hostel (Tilak Hostel) for the science students, named after the renowned freedom fighter Bal Gangadhar Tilak. While working as a research student leading to a Ph.D., he appeared for the Civil Services and the Indian Forest Service Examination (IFS) largely owing to then prevailing uncertainties for employment in the Education Sector. While appearing for the Personality Test, one of the benchmarks test criteria was a successful continuous walk of twenty-five km in four hours. For this I had about a few weeks for preparation and during that time I started long running and walking during early hours. Although later on, I joined another civil service but the joy and satisfaction of the morning walk was such that I adopted it for all time to come in my life.

At many places, more so in the densely populated and industrial cities, the atmospheric pollution renders the air hazardous, and therefore, unsafe for walking.

Generally speaking, the air pollution is due to presence of particulate matter (PM) such as soot, dust, sulphates, etc., and gaseous pollutants such as carbon monoxide, sulphur dioxide, nitrogen oxides, ozone, etc. Primary cause of these pollutants includes the burning of fossil fuels, industrial emissions, agricultural activities, waste burning, and natural causes like wildfires, releasing harmful matter into the atmosphere.

Particulate and Gaseous Pollutants

Particulate pollutants involve minute solid particles and liquid droplets suspended in the air of varying viz. PM2.5, PM10 micrometre or micron comprising of soot, black carbon, mineral dust, fly ash, nitrates, sulphates, pollen, etc. A micrometre is informally known as micron in common jargon, which is equal to one-millionth of a metre or a thousandth of a millimetre. The usual sources of particulate pollution are fossil fuels burning in power plants, motorized vehicles, etc., industrial emissions, biomass (waste) burning, agriculture activities including ammonia, pesticides, etc., construction, mining, wildfires and dust storms.

The most common gaseous pollutants are Carbon Monoxide, Sulphur Dioxide, Nitrogen Oxides and Ozone. Of these, the Carbon Monoxide is a colourless and odourless gas produced due to partial or incomplete combustion of fuels by vehicles, heating/burning; Sulphur Dioxide is mainly produced during the burning of coal and oil in power plants and other industries; and Nitrogen Oxides are also products of the combustion process in vehicles, power plants, etc. As for Ozone is concerned, the Stratospheric Ozone naturally formed in the process of the solar ultraviolet rays hitting Oxygen is considered good as it forms the protective atmospheric layer. On the other hand, the ground-level Ozone created as a secondary pollutant due to oxides of Nitrogen and volatile organic compounds (VOCs) reacting with sunlight forms harmful smog. Such VOCs are chemicals from paints, organic solvents, vehicle fuels, industrial processes, and Ammonia from fertilizers and livestock (urine/faeces).

Major Causes of Air Pollution Apart from the type and nature of pollutants, an aware health-conscious person must also know about the causes of air pollution that renders outdoor activities difficult and hazardous at times. The major sources of the said pollution are briefly summarized as under:

• Fossil Fuels, combustion thereof chiefly involving the fossil fuels, power plants, motorized vehicles, including heating and burning activities.
   
• Industrial processes, including manufacturing and running of factories, mining and related business establishments.
   
• Agricultural activities, chiefly owing to the use of chemical fertilizers, pesticides, and maintenance of livestock.
   
• Household chorus, owing to the cooking, heating, smoking, trash, cleaning agents.
   
• Natural occurrences of wildfires, dust storms, volcanic eruptions, etc.
   
• Waste management, by burning and dumping trash/ garbage.

Thus, primary as well as secondary pollutants are attributable largely to human triggered activities and natural events, too. Many chemical reactions produced secondary pollutants such as smog and acid rain. Fossil fuels such as coal, oil and gas combustion, burning, exhaust and non-exhaust emissions from electricity generation, transportation, heating and industrial manufacturing processes are major sources of atmospheric pollution. Agricultural activities, construction and mining, household activities and waste management too have a sizeable share leading to a recurring degradation of atmospheric conditions. As against above, the natural causes such as wildfires, volcanic eruptions, windblown dust and storms, and biological agents like pollen from plants, meld spores and dander are lesser yet potential sources of pollutants.

Parameters Impacting Atmospheric Conditions

The common parameter impacting atmospheric conditions as well as suitability for the man for the outdoor activities including walking is the air quality index (AQI) at the given time which is sum total of several factors. These factors include the density of the particulate and non-particulate matters, humidity, wind, temperature, pressure, dew point, ultra violet rays (UV index), and visibility owing to fog, etc. These factors are inter-related and fall in the categories of primary and secondary factors. While each of these factors have their own impact on atmosphere and consequent pluses and minuses on human health and their outdoor activities, here we shall mainly be dealing with the impact of AQI, fog and humidity on human outdoor activities and health, including the morning walk.

1.  Air Quality Index (AQI)

The AQI is a system of determining the complex air pollution data into a single and easily understandable data on health advisory indicating how clean or polluted it is and its impact on human health. The usual measurement of AQI is done through the ground-based monitors as well as satellites which constantly track factors in terms of PM2.5, PM10, Ozone, Carbon Monoxide, Sulphur Dioxide, nitrates, Ammonia, Lead, etc., generally converting their concentrations on a scale of O to 500. It ranges from good to hazardous with the ascending numbers, more is the number of PM2.5, PM 10, higher is the health risk (see Table below).

2. Dense Fog

Even if AQI is good, the dense fog can adversely affect health during a morning walk. A low AQI would mean that you are not inhaling large amounts of pollutants but the physical properties of fog itself might qualify to impact the human respiratory system leading to other health hazards. Actually, the fog comprises of tiny water droplets and inhaling the cold and damp air could cause airways to constrict, particularly among the people with prior conditions like asthma, bronchitis or other chronic obstructive pulmonary disease. The immediate symptoms may be coughing, wheezing and/or shortness of breath. The visibility itself might pose a considerable risk of accidents, especially for those walking on or near roads. Then people are also prone to catching infections, as the fog droplets are also capable of trapping allergens, bacteria, and viruses found at the ground level

Therefore, it is advisable to avoid going out when the weather out has dense foggy conditions. However, if AQI is good to moderate and a person is keen to go out, he must take adequate precautions for a safe morning walk. For this, one should wear appropriate dress in layers to stay warm and use a mask or scarf to cover mouth and nose to make sure that adequately warm and safe air is inhaled by lungs. People should avoid going out and resort to the yogic and aerobic exercises indoors when the fog is dense and visibility is severely low outside. Besides, one also needs to stay hydrated and consult his healthcare provider (doctor) for suitable advice on exercise and walk in foggy conditions.

3. High Humidity

As such, walking in high humid condition with good to moderate AQI is considered safe for healthy people, although it requires proper precautions owing to heavy moisture with a potential for trapped pollutants. Generally speaking, 40 to 60% humidity shall be considered ideal but in winters, air is saturated with as high as 98% or more humidity at many places. The high humidity makes air denser and heavier, which might offer airway resistance causing a sensation of breathlessness to sensitive people as well as children and elderly. Besides, humidity also serves like a blanket trapping fine particulate matter closer to several feet above the ground level. Further sweat evaporation in high humid conditions is also impaired, impacting body temperature regulation and consequent unwarranted fatigue or chill.

Due to the aforesaid reasons, sensitive group of people need to be mindful of the humid weather too. For instance, if a person has asthma, chronic obstructive pulmonary disease (COPD) or any heart conditions, high humidity may trigger bronchial constriction i.e. the narrowing of airways. Therefore, it is better to avoid outdoor activities, including walk, or reduce its intensity when humidity is very high (say 90% and above). Such people could opt for a walk after sunrise because the sunlight disperses moisture and trapped pollutants to a considerable extent improving both the air quality and body comfort. People can also opt for the protective gears like suitable clothing with moisture-wicking layers and facial masks, capable of filtering fine particles that might have been trapped in the humid air. Of course, alternatives like yoga or treadmill walking are always advisable both when AQI and humidity is beyond healthy range.

AQI Surge: Walking Hazards 

The Indian cities are experiencing a recurring patter of the worsening of air quality as the winter weather sets in November onwards. The Diwali festive season could be more appropriately taken as the usual benchmark following which the temperature starts falling in the large parts of the Northern India with AQI rising dramatically. The issue is so often politicised by the rival political parties in the metro cities like the national capital Delhi but the fact is none of them are able to effectively deal with this problem while in power. The usual pattern is that a thick blanket of smog develops across many cities and, consequently, the sky so often appears hazy, the air smells with unpleasant odour and breathing outdoors gets heavier than usual impacting millions of people.

While the common people suffer with the health and hazards posed thus as the AQI surges crossing the severe category thereby rendering the air unsafe to breathe for the humans of all ages, the politicians and their dedicated followers (sycophants, flatterers and bootlickers) simply blame it to the emissions of firecrackers during the festivities (mainly Diwali), stubble burning in certain northern states, particularly Punjab, vehicular emissions, construction activities, manufacturing as well as cold weather conditions. Blaming it on to a particular festival lasting 2-3 days seems purported and politically motivated to derive mileage out of it but largely it appears to be a cumulative impact of man driven activities which the man is unable to control or cop with. The consequent nemesis is the dramatical rise in respiratory discomfort, eyes irritation, itching and fatigue, cough and skin ailments even among healthy people, and aggravation of the condition of lungs and heart disease patients.

In the context of AQI, usually the is considered more or less safe from 0-100, a red flag with caution is raised up to 101 t0 200, as soon as it crosses 200 it is declared severe and unhealthy, while above 300 level the air is categorized as hazardous for human health. In many Indian cities, a constant trend of AQI 300 plus is noted during winter months which is definitely a cause of concern and dangerous for all living beings. Although, AQI below 50 is classified as “good” by the regulatory bodies but the fact is any level of PM2.5 exposure may not be entirely safe, and even low concentrations can cause damage over a period. Therefore, as a matter of fact, the said AQI with PM2.5 graded as “good” simply indicates the minimum level of the public health risk. In fact, the AQI is a public communication tool simplifying the complex air quality data associated with the public health advice and caution from the minimum to maximum risk levels.

Let’s understand then as to what is the rationale behind setting the AQI standards with the graded benchmarking. In a nutshell, these are relative pollution risks and person’s own body defence mechanisms vis-à-vis policies of the air quality evolved as science-based benchmarks. For instance, a level below 50 µg/m³ is considered "good" because the health risks at this concentration are significantly lower compared to high concentrations such as an AQI of 150 or 300 plus. Similarly, when AQI is low, the defence mechanism of a healthy body with its built-in antioxidants level and immune system may efficiently and successfully neutralize it with minimum stress over the respiratory system. Thus, the standards prescribed are essentially with an endeavour to strike a balance between ideally the theoretical zero-risk and realistic potential harms, which are needed as pollution control measures.

When people inhale particulate matter, the lungs primarily try to clear it via mucus and cilia with the larger particles getting trapped in mucus in airways and moved up by cilia (fine hairs) for coughing and/or swallowing. The small particles reach alveoli and are engulfed by immune cells (macrophages) digesting them. When the concentration of particles is more, they obviously bypass the defence mechanism and even enter blood stream, causing deep penetration, oxidative stress, impaired clearance, inflammation and cellular damages through blood in lungs and other organs such as heart and brain. In short, larger concentration of the particulate matter irritates, stresses and triggers inflammation disrupting normal lung repair leading to chronic disease and COPD exacerbation.

Fine particles (PM2.5) are capable of penetrating deep into the lungs and enter the bloodstream, thereby causing harm to almost each organ in the body. The immediate health hazards may involve respiratory symptoms like coughing, wheezing, shortness of breath, chest pain, burning sensation and reddening of eyes and skin, headache, nausea, dizziness, fatigue, including asthma attacks, heart attack and strokes in different people. The long-term health hazards due to prolonged exposures involve development of chronic respiratory diseases, cardiovascular diseases, neurological disorders and mental health issues, weak immune system, reproductive issues, and even cancer. Needless to mention, while a normal healthy adult is prone to the aforesaid health risks owing to the prolonged or chronic exposure, the children, elderly people and people with chronic conditions like asthma, COPD, or heart disease especially fall in a greater risk category.

What is Recommended on High AQI?

When the air quality is within the range of good to moderate AQI, people may opt for the early morning walk subject to other environmental conditions and stimuli such as fog, humidity, etc. However, when AQI falls in the range of poor/very poor to severe/hazardous levels, a lot of human deliberation and discretion is required. For instance, people could still exercise outdoors or go out for a walk with poor AQI taking adequate precaution and protection but with AQI above 200 falling under severe or hazardous levels, they must stay indoors avoiding exercise and walk in open. With increasing awareness and tools readily available to indicate weather conditions, people can easily minimize adverse effects of atmospheric pollution on their health.

Every aware person should develop a practice to monitor air quality on daily basis in checking AQI particularly during the winter months. These days several smart phone apps and websites provide real time updates on air quality of almost every location. So, whenever the AQI surge touches “very poor” or “severe” levels, it would be wise to minimize the outdoor exposure including the routines like walking and jogging; instead, settle for indoor activities like yoga and aerobic exercises. In such case, it’s also necessary that have a healthy indoor environment. Therefore, the windows and doors must be closed during the high smog period. These days, air purifiers with high efficiency particulate air (HEPA) filters are available with the capacity to capture more than 99% airborne particles, including dust, mold, pollen, and even micro germs. Certain indoor plants like the Snake plant, Areca Palm, Peace Lily, etc., could also be grown which are considered natural purifiers absorbing pollutants and augmenting oxygen.

When outside air is highly polluted, the dust accumulation inside too cannot be ruled out; hence it is necessary to properly manage ventilation points. In this endeavour, using humidifiers or even keeping bowls of water inside would help to maintain moisture in the air and trap the dust particles to a certain degree. Needless to mention, the inside floors and surfaces should be regularly cleaned. When the AQI is high beyond acceptable limit, it is wise to stay indoors and where necessary, one must protect self with an appropriate good quality mask. One needs to remember that only specified masks like N95 or N99 are effective in blocking particulate matter of PM2.5 category, the ordinary and even surgical masks are not designed to stop fine particulate matter.

Apart from the aforesaid measures, doctors and health experts advise to take special care in staying hydrated with good nutrition, which also plays a crucial role in combating with the pollution related stress and hardship. In the description in the foregoing paragraphs, it was mentioned that inhaled particulate matter causes oxidative stress and consequent damages in the body. Hence anti-oxidant rich foods need to be supplemented to neutralize these damages. Therefore, a regular intake of vitamin C-rich fruits like oranges, guava, lemon and amla and leafy greens (salads) like spinach, coriander and kale are recommended as they are known to be rich in vitamins and antioxidants. Similarly, intake of fish, walnuts and flax seeds being rich source of Omega-3 fatty acids, combined with anti-inflammatory spices like turmeric and ginger serve as the natural sources reducing inflammation and boosting immunity.

Taking Special Care of Vulnerable Groups

Vulnerable groups like children, elderly people and people with a history of chronic diseases especially related to lungs and heart are more at risk; hence need more protection and care. It is well known that children breath faster with a higher heart rate, so naturally their air intake is also relatively more compared to the normal adults. Similarly, the elderly people and people with known lungs or heart conditions too are more susceptible requiring extra precaution. To make sure that a person and family stay safe and healthy from the polluted atmosphere, the following precaution must be taken.

• Children, elderly and people with a history of chronic diseases must stay indoors when pollution i.e. AQI, fog is high outside. Children may be specially educated of the pollution
  health risks.
   
• Limit vigorous activity inside home and outdoor play/running when the AQI is high. People may opt for indoor activities like yoga, aerobics, breathing/light exercises particularly those that support the lung health and oxygen intake.
   
• Necessary tool kit viz. medicines, inhalers and emergency contacts shall be kept handy, which may be required in contingencies.
   
• Healthy diet rich in antioxidants shall be taken by all age groups.
   
• Proactive health check-up of the elderly people and people with a chronic history is desirable, including prompt consultation with medical expert(s) when needed.
   
• The use of air purifiers and dehumidifiers to maintain indoor atmosphere shall be practiced as per needs.
   
• Everyone must stay hydrated and avoid dense/traffic areas.
   
• Appropriate masks shall be used while in outdoors for whatever reasons.
   
• People with a history of asthma, bronchitis or heart issues may have prior health check-ups with the onset of winter season, especially lung function tests, blood pressure test, and allergy/oxygen level tests to pre-empt pollution effects.

Use of Masks

During the COVID-19 period (2020-22), maximum awareness about the use of masks was spread globally including in India and a variety of masks falling in the category of N95 masks, surgical masks, barrier face masks (of even fancy material and look), etc., providing various degrees of virus protection with relative advantages and disadvantages were popularized. Of these, the barrier face masks and surgical face masks are not found suitable for the protection against tiny dust particles and microbe present in polluted air. The barrier masks are of low efficiency offering least protection (about 40% or less) against PM2.5 according to reports while the surgical mask come with varying filtration efficiency (about 60-90%) but still fall short of the requisite standards due to various reasons. Accordingly, most experts recommend the use N95 or its variant masks such as N99, KN95, FFP2 that come with much higher efficiency viz. 95% and above.

N95 and N99 masks have NIOSH (National Institute for Occupational Safety and Health) certification and are readily available in India through retailers and online through e-commerce. Here “N” signifies that it is not resistant to oil-based particles and the numbers indicate the percentage of efficiency of filtration. A brief analysis of the two is given here. While N95 masks assure filtration of at least 95% airborne particles, N99 masks boasts of 99% efficiency, and both are effective for the outdoor walk and running. Here an important point to note is that although N99 mask offers a higher filtration rate but N95 is considered a better option in daily use as it balances filtration efficiency with a superior comfort and breathability. They are capable of capturing particulate matter of size 2.5 to 0.3 microns. Due to a higher breathing resistance, a prolonged use of N99 may cause tiredness and suffocation; hence their use is often advised for specific industrial and/or high-risk situations. Generally speaking, N95 masks are recommended for use owing to reasonably good protection and ease in breathing.

End Remarks

As such geographically India falls in a zone of the northern hemisphere more prone to heat, wind and dust and the situation is further aggravated due to vast population and associated human activities rendering the air more polluted and unsustainable during the winter months in the large part of the Northern India. In such a scenario, people need to develop constant awareness and safety measures in their daily routine to stay healthy and fit. In polluted atmosphere with unsustainable AQI, people need to limit their morning walk and other outdoor activities simultaneously taking prescribed precautions and safety measures. The working people must follow the recommended heathy practices particularly while outdoor (commuting) during the peak hours, say 8.00 to 10.00 AM in morning and 5.00 to 8.00 pm in the evening.

To recap in short, important health tips include the regular use of AQI apps for updates on pollution levels, stop or limit morning walk/outdoor exercises, wear appropriate mask outdoors s protection against the foul air, walk in parks and green areas with less traffic, keep windows and doors of house/office closed, use air purifiers and dehumidifier to keep inside air clean, take antioxidants-rich diet, especially take protective measures for children, elderly and other vulnerable groups, resort to yoga and breathing exercises, stay hydrated taking plenty of water, and take preventive health check-ups. Most of these recommendations and suggestions are based on experts’ opinion. The author would recommend one more: While following the recommended tips, even more important for you is to try, learn and listen to your own inner voice for dos and don’ts for you, nothing can beat it.

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