Air pollution does more than trigger asthma and wheezing. Stepping out in polluted air makes your eyes sting, your nose run, your throat dry and itchy, and your head ache. It often causes nausea, dizziness, headache and chronic allergy. Over time, it kills by triggering heart attacks, stroke and cancers.
Outdoor air pollution caused 6.2 lakh premature deaths in India in 2010, which is a six-fold jump from the 1 lakh deaths in 2000. This makes polluted outdoor air the fifth biggest killer in India after high blood pressure indoor air pollution (mainly from smoking chullahs that use biomass fuels such as wood, coal, straw, manure, etc), tobacco use, and poor nutrition, says the Global Burden of Disease 2013 (http://www.healthdata.org/research-article/global-regional-and-national-incidence-prevalence-and-years-lived-disability-2013), which tracks deaths and illnesses from all causes every 10 years.
It’s world’s biggest environmental health risk, exacerbating respiratory and heart diseases and triggering deaths from stroke (25.48%), chronic obstructive pulmonary disease (17.32%), heart disease (48.6%), lung infections (6.4%), and trachea, bronchus and lung cancer (2.02%).
One in three people in India live in critically-polluted areas that have noxious levels of nitrogen dioxide (NO2), sulphur dioxide (SO2) and lung-clogging suspended particulate matter smaller than 10 micron (SPM10) in size. Of the 180 cities monitored by India’s Central Pollution Control Board in 2012, only two -- Malapuram and Pathanamthitta in Kerala -- meet the criteria of low air pollution (50% below the standard).
Just being stuck in heavy traffic can trigger heart attacks. People who had had a heart attack were more than three times as likely to have been in traffic within an hour of getting a heart attack, found a study of 1,454 in Germany (http://www.sciencedaily.com/releases/2009/03/090313171310.htm), with risk being highest for women, people over 65 years and those with existing heart disease.
Exposure to traffic noise makes children hyperactive and sleepless, report researchers in the journal Environmental Research. Sleeping in rooms exposed to sound of nighttime traffic raises children’s blood pressure, reports a study in the journal Noise Health (http://www.ncbi.nlm.nih.gov/pubmed/236892980).
Here’s how the top three components of polluted air hurt your mind and body:
Smog is produced when airborne dust, carbon particles, noxious gases and ozone react chemically in the presence of sunlight to create a toxic mist that aggravates bronchitis, asthma, and other lung problems and reduces lung function even in healthy people. There are no safe levels of smog. Inhaling smog tightens the arteries, reducing the blood flow, and triggering heart attacks and stroke, report Harvard research in the journal Circulation (http://circ.ahajournals.org/content/128/21/e411.full). At most risk are people who have had a heart attack or angioplasty or those who have angina, heart failure, heart rhythm problems, and/or diabetes.
Ground-level ozone, which is the main constituent of smog that hangs low over Delhi throughout the year, irritates the eyes, nose, and throat. When it is inhaled, it dehydrates and inflames the protective membranes of the nose and throat, raising risk of throat and lung infections. Apart from aggravating asthma, exposure to ozone for just six to seven hours, even at relatively low concentrations, triggers asthma attacks, lowers lung function and triggers wheezing in healthy people. People over 65, children under 12 and people with asthma and lung disorders need to limit exposure as much as possible.
Suspended particulates (SPM10 and SPM2.5) from diesel and petrol fumes, power plants, industry, agricultural fires and construction dust remain hanging and air and cause irreversible damage lung and respiratory tissue damage. Combined with ground-level ozone, the main constituent of smog, SPM causes wheezing, coughing and breathing difficulties (especially during exercising).
SPM give lower visibility and contribute to the brownish-yellow colour characteristic of smog.
SPM2.5 and below are more deadly. Unlike larger particles that get filtered by the mouth and lungs, fine airborne particles are inhaled deeper and get lodged in the lower regions of the respiratory tract to lower the lungs’ working capacity and aggravates respiratory problems.
Over time, exposure damages lung tissue, causes cancer and premature death.
Nitrogen dioxide (NO2) and other oxides of nitrogen (NOX), formed from vehicular emissions and electricity and industrial plants, irritate the airways and cause frequent nose, throat and lung infections such as bronchitis and pneumonia.
People who live near busy highways are at most risk. NO2 concentrations are 30 to 100% higher within about 50 metres from busy roads as compared to areas away from roadways. Nox reacts with volatile organic compounds in the presence of heat and sunlight to form deadly ground-level ozone.
Sulphur dioxide (SO2) is released from burning fuels that contain sulphur (coal, oil, diesel etc) and from coal- and oil-fired power plants, pulp and paper mills, steel mills and smelters.
Short-term exposure affects breathing and causes wheezing, chest tightness, shortness of breath, sore throat and nose irritation. Long-term exposure aggravates breathing and heart problems, with people with asthma, chronic bronchitis, emphysema, children and people over 70 years old being at most risk.