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CUHK Releases the Third 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 two batches of environmental test results released earlier, the University announced today (20 December 2019) the third batch of test results, including the total cyanide levels in soil samples (#1 – #11), contaminants in air samples (A1 – A7), and a series of tear gas residue monitorings 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 in surface dust (Ni), in ambient air, environmental surfaces, and water was conducted.
As the three batches of campus environmental test results meet safety standards, the University has begun to clean up and rebuild the road surface of Campus Circuit East, and will reopen it for use next Monday (23 December).
The summary of the test results and the respective reference standards is as follows.
(1) Soil samples
Table 1: For soil samples (#1 – #11)
| Contaminant | Test Results | Reference Level | Reference Document |
| Total Cyanide | < 1.00 mg/kg | 4,900 mg/kg | Risk-Based Remediation Goals (RBRGs) for Soil – Public Parks, published by HKEPD |
(2) Air samples
Table 2: For air samples (A1 – A7)
| Contaminant | Test Results | Reference Level | Reference Document |
| Dioxins |
0.036 – 0.056 pg I-TEQ/m3 |
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 pg I-TEQ/m3 |
Hong Kong ambient air monitoring (the lowerest and highest readings of Dioxins between 1999 and 2019) | ||
| Total PCBs |
0.330 – 0.701 ng/m3 |
1,200 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 (the lowerest and highest readings of Total PCBs between 1998 and 2001) | ||
|
PAHs as benzo[a]pyrene (BaP) |
< 0.060 – 0.147 ng/m3 |
87 ng/m3 | WHO, 2000 – a cancer risk of one in a 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 (the lowerest and highest readings of BaP between 1997 and 2001) |
(3) Test results of five chemical components in tear gas residue
Table 3: The test methods, reporting limits and the respective harmful limits of the five chemical components are tabulated below:
| Chemical Name | Test Method | Reporting Limit | Harmful Limit (OSHA Standard) |
| 2-Chlorobenzalmalononitrile (CS) | NIOSH 304 | 0.1 mg/m3 | 0.4 mg/m3 (skin) |
| Alpha-Chloroacetophenone (CN) | NIOSH 291 | 0.1 mg/m3 | 0.3 mg/m3 |
| Capsaicin and dihydrocapsaicin (OC) | NIOSH 5041 | 0.1 mg/m3 | N/A |
| Hydrogen cyanide (HCN) | NIOSH 36010 | 0.2 mg/m3 | 11.05 mg/m3 (skin) |
| Nickel in surface dust (Ni) | NIOSH 7300 | 0.1 mg/m3 | 1 mg/m3 |
Conclusion
(1) Soil samples
The total cyanide levels in soil samples (#1 – #11) are all lower than their reporting limits (i.e. 1.00 mg/kg), which are well below the Risk-Based Remediation Goals (RBRGs) of total cyanide level in soil for public parks (i.e. 4,900 mg/kg) as quoted in the Guidance Manual for Use of Risk-Based Remediation Goals for Contaminated Land Management published by the Hong Kong Environmental Protection Department (HKEPD) in 2007 (see table 1).
This indicates that the total cyanide levels in these soil samples are not significant and the results are comparable to other soil samples (S1 – S9) collected in the more distant locations away from No. 2 Bridge.
(2) Air samples
Seven ambient air samples (A1 – A7) were collected both in indoor and outdoor environments around the most affected areas in the vicinity of 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 HKEPD in 2003 are imposed for comparison.
Table 2 shows that all test results for air samples (A1 – A7) are well below their respective reference level of international guidelines or within Hong Kong ambient air monitoring data.
(3) Test results of five chemical components in tear gas residue
The first batch of tear gas residue samplings took place in the Jockey Club Postgraduate Hall 1 and covered nine air samples, nine surface swab samples, and six water samples. The results revealed that the chemical components in these samples are well below their respective reporting limits (see table 3). Other test results of tear gas residue monitoring covering other areas such as the University Sports Centre, the University’s main entrance, and New Asia College will be uploaded onto the CUHK website as soon as available.
In conclusion, the health hazards of the aforementioned contaminants in the soil (#1 – #11) and air (A1 – A7) samples, as well as the five chemical components in tear gas residue are negligible.
Related information may be viewed here (www.cuhk.edu.hk/english/whats-on/focus/campus-env-result.html).
