Announcements
CUHK Releases the Fourth Batch of Test Results on Campus Environment
The Chinese University of Hong Kong (CUHK) earlier appointed an independent accredited laboratory to collect air, water and soil samples at various locations and at different times on campus and sent them for testing. Further to the three batches of environmental test results released earlier, the University announced today (3 January 2020) the fourth batch of test results, which are contaminants in air samples (A8 – A18) and a series of tear gas residue monitoring in response to the concerns of some University members over the tear gas residue hazards on CUHK campus. An analysis of five chemical components in tear gas residue including 2-chlorobenzalmalononitrile (CS), alpha-chloroacetophenone (CN), capsaicin and dihydrocapsaicin (OC), hydrogen cyanide (HCN), and nickel (Ni) in surface dust in ambient air, environmental surfaces, and water was conducted.
The summary of the test results is as follows.
(1) Air Samples
Table 1: For air samples (A8 – A18)
This batch of ambient air samples (A8 – A18) was collected both from indoor and outdoor environments around the most affected areas and more distant locations away from No. 2 Bridge. Since Hong Kong has no ambient air standards for dioxins, PCBs and PAHs, some previous statistical data of ambient air monitoring in Hong Kong and international guidelines as cited in the Final Report of < Assessment of Toxic Air Pollutant Measurements in Hong Kong > issued by the Hong Kong Environmental Protection Department (HKEPD) in 2003 are imposed for comparison.
For ease of reference, please refer to the following table for the test results of each testing parameter with a comparison to some international guidelines and Hong Kong ambient air monitoring data performed by HKEPD.
Table 1: Air Samples (A8 – A18)
| Contaminant |
Test Results |
Reference Level |
Reference Source |
|
Dioxins |
0.053 – 0.069 |
0.6 pg I-TEQ/m3 |
Japan MOE, 1999 : ambient air standard (annual average) |
|
40 pg I-TEQ/m3 |
U.S. – California, OEHHA, 2002 : Chronic inhalation exposure limit |
||
|
0.001– 0.222 |
Hong Kong ambient air monitoring (Dioxins) from Year 1999-2019 |
||
|
Total PCBs |
0.286-0.949 |
1200 ng/m3 |
U.S. – California, OEHHA, 2002 : Chronic inhalation exposure limit |
|
83 ng/m3 |
U.S. – North Carolina, NCDENR, 2002 : acceptable ambient air level (annual average) |
||
|
0.01 – 2.18 ng/m3 |
Hong Kong ambient air monitoring (Total PCBs) from Year 1998-2001 (annual average) |
||
|
PAHs as benzo[a]pyrene (BaP) |
< 0.075 – 0.151 ng/m3 |
87 ng/m3 |
WHO, 2000 – a cancer risk of one in million |
|
33 ng/m3 |
U.S. – North Carolina, NCDENR, 2002 : Acceptable ambient air level (annual average) |
||
|
0.01 – 1.68 ng/m3 |
Hong Kong Toxic Air Pollutant monitoring (BaP) from Year 1997-2001 |
(2) Test result of five chemical components in tear gas residue
This batch of tear residue samplings took place in the University Sports Centre, areas near the University’s main entrance and New Asia College and covered nine air samples, nine surface swab samples, and six water samples.
The results of on-site air sampling and swab sampling showed the concentration levels of tested pollutants (2-chlorobenzalmalononitrile (CS), alpha-chloroacetophenone (CN), capsaicin & dihydrocapsaicin (OC), hydrogen cyanide (HCN), and nickel surface dust) were below reporting limit and hence they were not detectable in the air and sampled surfaces.
The results of water sampling showed the concentration levels of tested pollutants (CS, CN, capsaicin & OC, and HCN) were below reporting limit and hence they were not detectable in the water sources. The results of nickel in water sampling showed the concentration levels were from < 1 μg/L to 2.0 μg/L. In accordance with the drinking water standards as stipulated in World Health Organization – Guidelines for Drinking Water Quality (4th edition), the concentration of nickel in water samples are not significant.
Table 2: Results of on-site air sampling and swab sampling, water sampling
| Chemical Name |
Air Samples |
Swab Samples |
Water Samples |
||
|
Test Result |
Ref. limit (mg/m3) |
Test Result |
Test Result |
Ref. limit |
|
|
2-Chlorobenzalmalononitrile (CS) |
< 0.1 |
0.4 |
< 0.2 |
< 1 µg/L |
—– |
|
Alpha-Chloroacetophenone (CN) |
< 0.1 |
0.3 |
< 0.2 |
< 1 µg/L |
—– |
|
Capsaicin |
< 0.1 |
—– |
< 0.5 |
< 0.2 mg/L |
—– |
|
Dihydrocapsaicin |
< 0.1 |
—– |
< 0.5 |
—– |
|
|
Hydrogen cyanide (HCN) |
< 0.2 |
11.05 |
< 0.5 |
< 0.02 mg/L |
0.07 mg/L |
|
Nickel (Ni) |
< 0.05 |
1 |
< 0.5 |
< 1 – 2.0 µg/L |
70 µg/L |
Remarks: *Occupational Safety and Health Administration of United States Department of Labor.
#World Health Organization – Guidelines for Drinking Water Quality, 3rd & 4th edition.
Conclusion
In conclusion, all the test results for air samples (A8 – A18) are well below their respective international guidelines or within Hong Kong ambient air monitoring data. In view of the aforementioned interpretation, the health hazards of these contaminants from air samples (A8 – A18) are negligible.
According to the test result of five chemical components in tear gas residue, the health hazards of these chemicals are also negligible.
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