Asthma is characterized by a predisposition to chronic inflammation of the lungs in which the airways (bronchi) are reversibly narrowed. The National Heart, Lung and Blood Institute defines asthma as a common chronic disorder of the airways characterized by variable and recurring symptoms, airflow obstruction, bronchial hyper responsiveness and an underlying inflammation. Because of the spectrum of severity within the asthma, some people with asthma only rarely experience symptoms, usually in response to triggers, where as other more severe cases may have marked airflow obstruction at all times. Asthma exists in two states: the steady state of chronic asthma, and the acute state of an acute asthma exacerbation. The symptoms are different depending on what state the patient is in. Common symptoms of asthma in a steady-state include: nighttime coughing, shortness of breath with exertion but no dyspnea at rest, a chronic 'throat-clearing' type cough, and complaints of a tight feeling in the chest. Severity often correlates to an increase in symptoms. Symptoms can worsen gradually and rather insidiously, up to the point of an acute exacerbation of asthma. It is a common misconception that all people with asthma wheeze—some never wheeze, and their disease may be confused with another chronic obstructive pulmonary disease such as emphysema or chronic bronchitis. An acute exacerbation of asthma is commonly referred to as an asthma attack. The cardinal symptoms of an attack are shortness of breath (dyspnea), wheezing, and chest tightness. Although the former is often regarded as the primary symptom of asthma, some patients present primarily with coughing, and in the late stages of an attack, air motion may be so impaired that no wheezing may be heard. When present the cough may sometimes produce clear sputum. The onset may be sudden, with a sense of constriction in the chest, as breathing becomes difficult and wheezing occurs (primarily upon expiration, but sometimes in both respiratory phases). It is important to note inspiratory stridor without expiratory wheeze however, as an upper airway obstruction may manifest with symptoms similar to an acute exacerbation of asthma, with stridor instead of wheezing, and will remain unresponsive to bronchodilators.

Signs of an asthmatic episode include wheezing, prolonged expiration, a rapid heart rate (tachycardia), and rhonchous lung sounds (audible through a stethoscope). During a serious asthma attack, the accessory muscles of respiration (sternocleidomastoid and scalene muscles of the neck) may be used, shown as in-drawing of tissues between the ribs and above the sternum and clavicles, and there may be the presence of a paradoxical pulse (a pulse that is weaker during inhalation and stronger during exhalation), and over-inflation of the chest. During very severe attacks, an asthma sufferer can turn blue from lack of oxygen and can experience chest pain or even loss of consciousness. Just before loss of consciousness, there is a chance that the patient will feel numbness in the limbs and palms may start to sweat. The person's feet may become cold. Severe asthma attacks, which are not responsive to standard treatments, called status asthmatics, are life threatening and may lead to respiratory arrest and death. Though symptoms may be very severe during an acute exacerbation, between attacks a patient may show few or even no signs of the disease. Asthma is caused by environmental and genetic factors, which can influence how severe asthma is and how well it responds to medication. Some environmental and genetic factors have been confirmed by further research, while others have not been. Underlying both environmental and genetic factors is the role of the upper airway in recognizing the perceived dangers and protecting the more vulnerable lungs by shutting down the airway. Asthma, in this view, is seen as an evolutionary defense. This view also suggests that removing or reducing the nasa pollutants should be successful at reducing the problem.

India accounts for one third of the world's 115 million asthma patients - and environmental pollution and poor awareness are some of the reasons. Pulmonologists and asthmatologists said the prevalence of pollen allergy, dust and mite allergy in an already polluted environment, and the growing pressures of urban living are fuelling the spurt in respiratory diseases in India. It is estimated that there may be an additional 100 million people with asthma by 2025. Since 2008 we have active in this topic and arrange camp and give the real reason for this disease.