Ozone can affect both healthy people and those suffering from respiratory illnesses such as asthma. Epidemiological studies done in the US and Europe have shown worsening of asthma symptoms, a spurt in use of medicine for treatment of respiratory problems and increase in hospital admissions due to asthma attacks during or immediately after "asthma episodes' in laboratories. Studies have also established rise in incidence of asthma in areas with high levels of ozone. Even in healthy people, short exposure to high levels of ozone affects lung function. The symptoms