TABLE 6. Changes in Air Pollutants Induced by COVID-19 Related Lockdown Measures (’−’ Sign inDicates a Decrease and ’+’ Sign Indicates an Increase in Pollutants).

Study	,	,	,
[93]	–	−33%	−15%	–	–
[96]	–	–	−4% (for lockdown), −47% for post lockdown with previous year	–	–
[97]	–	−(36.9 - 41.6)%	−(6.6 - 14.2)%	–	+ (11.6 - 33.8)%
[98]	–	−18%	–	–	+50%
[99]	–	−50%	–	–	–
[100]	–	−36%	Insignificant change	–	–
[101]	Decreased	Decreased	Both Decreased	Decreased	Increased
[102]	−8.8%	−20.4%	−26%	−17.5%	−9.7%
[103]	Decreased	Decreased NO &	Decreased &	–	Decreased
[107]	Insignificant change	−63% (fell by 24ug/m3)	−63%	Insignificant change	–
[109]	–	−33%	−7%	−7%	–
[111]	−(7–11)%	− (23 - 37)%	−(14 - 20)% , −(7 - 16)%	−(2 - 20)%	–
[112]	decreased	−(36–53)%	Decreased	–	Decreased