id	keyword
american_scientific_journal-1273	distribution
american_scientific_journal-1273	parameter
american_scientific_journal-1273	burr
american_scientific_journal-1273	data
american_scientific_journal-1273	nitrogen
american_scientific_journal-1273	xii
american_scientific_journal-1273	air
american_scientific_journal-1273	maximum
american_scientific_journal-1273	dioxide
american_scientific_journal-1273	dagum
american_scientific_journal-1273	concentrations
american_scientific_journal-1273	pollution