I was curios, my 02 level is anywhere from 4 to 6 lpm.
So I got curios and did a little research on this.
Here is some of what I found. It may not affect you but it is worth the reading...some of this causes damage to the (alveolar Saks )

http://en.wikipedia.org/wiki/Oxygen_toxicity#Pulmonary

Pulmonary

Pulmonary toxicity symptoms result from an inflammation that starts in the airways leading to the lungs and then spreads into the lungs (tracheobronchial tree). The symptoms appear in the upper chest region (substernal and carinal regions).[25][26][27] This begins as a mild tickle on inhalation and progresses to frequent coughing.[25] If breathing elevated partial pressures of oxygen is not discontinued, patients experience a mild burning on inhalation along with uncontrollable coughing and occasional shortness of breath (dyspnoea).[25]

Physical findings related to pulmonary toxicity have included bubbling sounds heard through a stethoscope (bubbling rales), fever, and increased blood flow to the lining of the nose (hyperaemia of the nasal mucosa).[27] The radiological finding from the lungs shows inflammation and swelling (pulmonary oedema).[25][26]

Pulmonary function measurements are reduced, as noted by a reduction in the amount of air that the lungs can hold (vital capacity) and changes in expiratory function and lung elasticity.[27][28] Tests in animals have indicated a variation in tolerance similar to that found in central nervous system toxicity, as well as significant variations between species. When the exposure to oxygen above 0.5 bar (50 kPa) is intermittent, it permits the lungs to recover and delays the onset of toxicity.[29]

Pulmonary toxicity

The lungs, as well as the remainder of the respiratory tract, are exposed to the highest concentration of oxygen in the human body and are therefore the first organs to show toxicity. Pulmonary toxicity occurs with exposure to concentrations of oxygen greater than 0.5 bar (50 kPa), corresponding to an oxygen fraction of 50% at normal atmospheric pressure. Signs of pulmonary toxicity begins with evidence of tracheobronchitis, or inflammation of the upper airways, after an asymptomatic period between 4 and 22 hours at greater than 95% oxygen,[34] with some studies suggesting symptoms usually begin after approximately 14 hours at this level of oxygen.[35]

At partial pressures of oxygen of 2 to 3 bar (200 to 300 kPa)100% oxygen at 2 to 3 times atmospheric pressurethese symptoms may begin as early as 3 hours after exposure to oxygen.[34] Experiments on rats show pulmonary manifestations of oxygen toxicity are not the same for normobaric conditions as they are for hyperbaric conditions.[36] Evidence of decline in lung function as measured by pulmonary function testing can occur as quickly as 24 hours of continuous exposure to 100% oxygen,[35] with evidence of diffuse alveolar damage and the onset of acute respiratory distress syndrome usually occurring after 48 hours on 100% oxygen.[34] Breathing 100% oxygen also eventually leads to collapse of the alveoli (atelectasis), whileat the same partial pressure of oxygenthe presence of significant partial pressures of inert gases, typically nitrogen, will prevent this effect.[37]

Preterm newborns are known to be at higher risk for bronchopulmonary dysplasia with extended exposure to high concentrations of oxygen.[38] Other groups at higher risk for oxygen toxicity are patients on mechanical ventilation with exposure to levels of oxygen greater than 50%, and patients exposed to chemicals that increase risk for oxygen toxicity such the chemotherapeutic agent bleomycin.[35] Therefore, current guidelines for patients on mechanical ventilation in intensive care suggests keeping oxygen concentration less than 60%.[34] Likewise, divers who undergo treatment of decompression sickness are at increased risk of oxygen toxicity as treatment entails exposure to long periods of oxygen breathing under hyperbaric conditions, in addition to any oxygen exposure during the dive.[31]