Air pollution is one of the biggest problems in our urban areas. There are many factors behind this, including urbanisation, heavy increase in number of vehicles, rapid growth of unplanned population and lack of good public transport. The increasing rate of pollutants in the air is the key measure that creates smog and contributes to damaging the ozone layer. Karachi is the most polluted city in the country and also among the top 10 cities of the world with the highest level of lead poisoning. During the last three decades, air pollution and its effects on health have been the popular topics for researchers to explore aspects of pollution such as suspended particulate matter and ozone layer depletion. Such phenomena have been associated with the increase in mortality rates and hospitals admissions due to respiratory and cardiovascular disease. These effects have been found in short-term studies, which relate day-to-day variations in air pollution and health and long-term studies, which have followed cohorts of exposed individuals over time. Effects have been seen at a very low level of exposure, and it is unclear whether there can be levels of suspended particulate matter and toxic gases such as SOX and NOX below which no effect on health are likely. Airborne pollutants enter deep into the lungs and, from there, enter the blood stream, causing cardiopulmonary disease, cancer and possibly premature births. The Environmental Performance Index (EPI) ranks how well countries perform on high-priority environmental issues in two broad policy areas: protection of human health from environmental harm and protection of ecosystems. According to EPI 2014, Pakistan ranks 148 out of 178 countries with a score of 34.58. In air quality, the score is 23.02 ranking 175, and this worst possible air quality is alarming. Air quality measures population-weighted exposure to fine particulate matter and the percentage of the population burning solid fuel for cooking. The 2014 EPI is a joint project between the Yale Centre for Environmental Law and Policy (YCELP) and the Centre for International Earth Science Information Network (CIESIN) at Columbia University. The International Agency for Research on Cancer (IARC) has classified air pollution from traffic and industrial fumes as a definite cause of lung cancer and has also linked them to bladder cancer. The strong verdict from IARC, a cautious body that makes a declaration only when the evidence is strong, will put pressure on governments around the world to take action. Circa April 2013, Karachi had an estimated population of 23.5 million people and is the third largest populous city of the world. It is also the most pollution-affected city in Pakistan. As per the 2014 pollution index, the pollution score of Karachi is 97.15 making it the sixth most pollution-affected city in the world. Rapid industrialisation and urbanisation in the metropolitan areas of Karachi are responsible factors for adverse environmental conditions. The main pollution sources in Karachi are smoke and noxious gases from the many old and defective vehicles. There are two stroke engines in auto-rickshaws and old buses, which are illegally plying around in the city. These vehicles produce excessive carbon monoxide and lead; these two are the major pollutants being regularly released into the atmosphere. It is not out of place to say that Karachi is at a high risk of extensive air pollution-related health hazards. The number of vehicles in Karachi is increasing every passing day in a steeply rising trend. The traffic jams that are often seen on the major roads of the city are harming the public in one way or the other. One of the most decisive factors driving environmental degradation in Karachi is its population growth. Both increasing birth rates and demographic migrations contribute to this. Air pollution is currently costing Pakistan one percent of its total GDP in the form of respiratory health problems and premature deaths. We are losing 30,000 children to poor environmental conditions in homes and 25,000 adults to overall air pollution in the country every year. There are numerous diseases the people are suffering from due to air pollution. There is growing concern that human destruction of the environment is responsible for causing and aggravating many illnesses. Many authors blame global warming and ozone depletion for an increase in the incidence of skin cancer, malaria and other vector-borne diseases. Some argue that chronic illnesses such as asthma and allergies are directly related to air pollution. Pollution is a universal issue and needs urgent government intervention with global support, if necessary, in terms of technology and containment measures. Regular ambient air quality monitoring at all major localities is necessary to first identify the biggest contributing sources and then to control them. A big part of this lies in the detection and confiscation of vehicles not complying with current emission norms, including salvaging any that can be salvaged. Other than that, new vehicles should be allowed to be sold only if they comply with Euro III or IV standards. And, finally, there should be strict regulations on industrial stack emissions through the use of scrubbers, electrostatic precipitation as well as wet and dry dust collectors. The writer is a freelance columnist and independent researcher. He can be reached at janjuaharoon01@gmail.com and tweets @JanjuaHaroon