TABLE 3.

Results from case studies: pollutants analyzed by each study [Color table can be viewed at wileyonlinelibrary.com]

Reference	Pollutant
	PM10	PM2.5	NO2	SO2	CO	O3	Others
73		X	X			X
74	X	X	X
86		X	−65%
46	X	X	−36%	X	X	X
72		−13% / ‐86%
64		X	X				NO, NOx
80	X	X	X	X	X	X
13	−43%	−31%	−18%		−10%	Factor of 1.5–2
127
87		X	−25%
105			−12%
120	X	−8%	X	X		+14%
91	X		X
150	X
121			X	X	X
59	X		X	X	X	X
156	X	X	X
94		X
60		X	X	X	X	X
88			−49%		−37%
89	−31%	−39%
108		−29%	−50%	X	X
63	X	X	X	X	X	X	NOx, Benzene
161			−2% / ‐70%
109		X
97	X	X	X		X	X
19	X	X	X			X
159			−45%		−46%	−61%
99	−44%	−40%	−60%
151			X
68	−9% / ‐21%	−11% / ‐26%	−10% / ‐19%	X
81	X	X	−12% / ‐60%	X	X
143	X	X
75			−19% / ‐83%	−71%	−4%		HCHO
110		X
69	−60%	−60%	−40%			−40%
111		−30%	−17%
158			−35%		−35%
132		−10%	−17%		−16%
66	−15%	−8%	−6%			+13%
129		X
67			−90%
52	X	X	X	X	X	X
95							Ultrafine particle
114			−40%	−43%		+7%
113	−35%	−45%	−20%	X	−17%	X
104	−31%	−32%	−64%	−20%	−31%
70	X		−12%
78		−21%	−35%	X	−49%	+15%	BTEX
141	X	X	−45%
142		−10% / ‐54%
82	−55%	−49%	−60%	−19%
162			X		X		Aerosol
137	X	X
115		−32%	−45%	−20%
122			X
125		−30%	−60%	−20%	−42%		NO, NOx, CO2, OC, EC
163	−14% / ‐20%	−7% / ‐16%	−23% / ‐37%	−2% / ‐20%	−7% / ‐11%	+10% / +27%
92		−19%	−16%		−25%
45	X	X	X	X
153	−14%		−41%			+34%
133	−50%	−50%	X		X		NH3
139	X	X	−57%	X	−30%		NO, NH3
147	X	X	X	X	X	X
144	−32%	−40%	−13%	X	X
47	X	X	X			X
62	−36%	−28%	X	X	X	X	NO, NOx, NH3, VOCs
53			−30%
152			−50%
85	X		−54%		−65%	+30%	NO
106	X	X	−20%	X	X	X
128	X	X	X		X	X
148			−55%			X
160	−50%		−50%	−50%
103			−13%
57	X	X	X
54		X				X
119		X	X	X
96			X		X	X
56		−50%
145		−26%	−20%	−17%	−9%	−10%
164		−12%
55	X	X	−50%			+20%	NO, NOx
155	−10%		−50%				NO, NOx
100		X	X			X
165	X	X	X		X
134			−50%
136	X		X
107	−40%	−44%	−51%	−21%
138	X	X	−30% / ‐84%	X	X	+16% / +58%
131	X	−36%	X		X
140	X	X	X	X	X
134			−50%
84	−8% / ‐42%	−8% / ‐42%	−56%			+17 / +36%	NO
98			X			X	NMVOC
76	X	X	X	X	X	X
135	X	X	X	X	X	X
93		−12%				X
118	−23%	−21%	−33%
79	−33%	−41%	−50%		−16%	+149%
83	X		−50%	X		+50%	BC
102	X	X	X	X	X	X
146			−85%
157	−45%		−50%		−51%
61	X	X	X	X	X	X
112			X
43		X				X
116	−33%	−21%	−38%		−20%
149			−14% / ‐38%
90		−33%	−29%		−17%		NO, NOx
136	−50%	−50%	−65%
126	−58%	−47%	−83%	−11%	−30%	+125%
101		−29%	−68%	−48%	−38%
33		X	X
65		X	X
124	−30%	−37%	−52%	−29%	−33%	X
130			X			X
117		X	X	X	X	X
123		X
154	X	X
77			X			X

Note: Concentration values worsened during lockdown were indicated in red, unchanged values in yellow and decreasing values in green and, when available, the relative percentage values.