Table 2

Baseline characteristics according to quartiles of nitrogen dioxide levels

Lowest (Q1)
(n=10,214)
Second (Q2)
(n=9682)
Third (Q3)
(n=10,517)
Highest (Q4)
(n=9378)
P value
AgeMean, SD62.708.6462.568.9261.978.8462.099.06
Men480247.0%463947.9%486346.2%440647.0%0.128
Insurance feeLowest217521.3%250725.9%306429.1%276929.5%<0.001
Second143914.1%162516.8%208919.9%194320.7%
Third462245.3%334034.5%274026.1%228824.4%
Highest197819.4%221022.8%262425.0%237825.4%
UrbanizationHighly176217.3%199420.6%341932.5%479451.1%<0.001
Moderately285628.0%370238.2%396537.7%241925.8%
Boomtown127012.4%129213.3%211520.1%148415.8%
Others432642.4%269427.8%10189.7%6817.3%
AMD*2872.8%3143.2%3323.2%5065.4%<0.001
Alcoholism5835.7%4664.8%5765.5%4254.5%<0.001
IHD435042.6%404841.8%413639.3%371239.6%<0.001
COPD317331.1%305931.6%309729.4%259327.6%<0.001
DM251124.6%230023.8%249223.7%228424.4%0.360
Hyperlipidemia442843.4%405741.9%460843.8%429745.8%<0.001
Hypertension724070.9%676469.9%717368.2%647169.0%<0.001
  • *Indicating newly diagnosed AMD during follow-up rather than baseline patients with AMD.

  • AMD, age-related macular degeneration; COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; IHD, ischemic heart disease.