Following is a question by the Hon Andrew Wan and a written reply by the Secretary for Security, Mr John Lee, in the Legislative Council today (November 20):

Question:
 
     It has been reported that on the afternoon of October 28 this year, a number of members of the public smelled a pungent odour akin to the smell of tear gas in the vicinity of Leung King Estate of Tuen Mun, and the odour subsequently spread to the vicinity of Tuen Mun Town Centre and the pier. A number of persons were unwell and made assistance calls for emergency ambulance service.  Later on that day, the Police posted on a social media platform a message stating that the Police and fire personnel, after conducting inspections, could not ascertain the cause and origin of the odour. The Police also clarified that they had not used tear gas nor, as circulated on the Internet, conducted testing of any unknown gas, in Tuen Mun that day. Suspecting that the odour was associated with Police operations, some residents gathered outside Tai Hing Operational Base that night, and the rally eventually developed into confrontations between the Police and members of the public. The Police fired multiple rounds of tear gas to disperse the crowd, with some of the rounds landing on the podium or corridor of some private housing courts. In this connection, will the Government inform this Council:
 
(1) whether it will continue to investigate the origin and cause of the aforesaid odour and if the odour was associated with tear gas; if it will, of the details; if not, the reasons for that;
 
(2) whether it knows if the Chinese People's Liberation Army Hong Kong Garrison (Hong Kong Garrison) used in its military sites on that day any equipment that would emanate pungent odour; if it knows of any such cases, of the details; if not, whether it will make enquiries with the Hong Kong Garrison; and
 
(3) whether the police officers concerned had taken into account the potential health hazards caused to innocent members of the public before firing tear gas rounds at residential buildings; if so, of the details; whether the Police will undertake not to adopt such a practice again; if they will not, of the reasons for that?
 
Reply:
 
President,
      
     On the suspected irritant odour incident reported in different areas of Tuen Mun on October 28 this year, relevant government departments have been proactively following up and made responses. On November 1, the Government also issued a consolidated response on the follow-up and investigation work in respect of the incident.  The follow-up work of various government departments on the above incident is summarised as follows:
 
(1) The Fire Services Department (FSD) received 18 emergency calls regarding a pungent odour in Tuen Mun district between 3.33pm and 4.25pm on October 28. FSD immediately despatched its personnel to investigate along Pui To Road, Ming Kum Road, Tin King Road, Shek Pai Tau Road, Ching Chung Koon Road, Tsun Wen Road and its vicinity, as well as entering the Tai Hing Operational Base for investigation. No unusual smell was detected during the operation. On the following two days (October 29 and 30), FSD continued to conduct investigations into the relevant areas and again could not detect any unusual smell. FSD did not receive any further emergency calls from the public reporting unusual odours in these areas.
 
(2) Since 3.34 pm on October 28, the Police have received multiple reports that there was an irritant odour in the vicinity of Tuen Mun. Police and FSD officers attended the scene, yet initial investigations could not confirm the odour's cause and origin. The incident was classified as an odd smell found case. The Police clarified that they did not use tear gas or conduct testing of any unknown gas in Tuen Mun during daytime on that day, as circulated on the Internet.
 
(3) The Environmental Protection Department (EPD) received 10 complaints of an odd smell between 3.50pm and 4.59pm on October 28. Upon arrival on site at around 5.35pm and having touched base with FSD officers, EPD officers conducted investigations in the vicinity of Tai Hing Operational Base, Blossom Garden, Venice Garden, Tuen Mun North West Swimming Pool, Leung King Estate and Tin King Estate. No obvious smell or suspicious odour could be traced.
 
     EPD officers conducted further investigations again on October 29 and 30 and November 1, with the area expanded to cover Kwong Shan Tsuen, the residential areas and schools nearest the Tsing Shan Firing Range, Kin Sang Estate, Shek Pai Tau Road, Shan King Estate, Tai Hing Estate, Chelsea Heights, Choy Yee Bridge, Ho Tin Stop, Tuen Mun Stop, Tuen Mun Heung Sze Wui Road and Siu Hei Stop. Drainage manhole covers as well as exhaust outlets of food premises and industrial buildings along the way in the area were also inspected in order to trace any possible residue smell or its source, but none was detected.
 
     EPD analysed the meteorology and air quality monitoring data obtained on October 28. The South China region was affected by a southward moving northeast monsoon on that day. The wind direction in Hong Kong changed from easterly to north-westerly since noon and brought in an air mass with a higher background pollution level, resulting in higher than normal pollutant concentrations (including ozone, nitrogen dioxide, PM10 and PM2.5) since around noon. Elevated pollution levels in Hong Kong occur often in autumn and winter. Its impact could affect various regions in Hong Kong, not only Tuen Mun. Exposure to ozone can cause irritating effects on humans. However, the level of ozone recorded on October 28 was not exceptionally high for autumn and winter. The highest concentration recorded on that day was less than half of the highest value recorded this September. It is not conclusive that ozone was the main cause of the irritant odour.
 
     The operation outside the Tai Hing Police Operational Base in Tuen Mun on the evening of October 28 was law enforcement action taken by the Police in accordance with their statutory duty. In view of such serious illegal acts as road blocking, unlawful assemblies and violent confrontations at the place during the time, the Police took action after conducting a risk assessment. The operation concerned was not related to the suspected irritant odour reported during daytime.
 
     My reply to the various parts of the question is as follows:
 
(1) Various government departments have thoroughly investigated the above incident. There has been no new finding. They will continue to monitor the situation.
 
(2) The Chinese People's Liberation Army Hong Kong Garrison performs its defence functions and responsibilities in Hong Kong in strict accordance with the Basic Law and the Law of the People's Republic of China on the Garrisoning of the Hong Kong Special Administrative Region. We do not comment on defence functions which are not the affairs of the Hong Kong Special Administrative Region Government.
 
(3) The Police stress that they would not need to use any force if members of the public could express their views in a peaceful and rational manner. The Police have the statutory duty to safeguard the public safety and public order of Hong Kong. It will be beneficial to all aspects if members of the public can co-operate with the Police in their law enforcement actions.
 
     The Police use tear gas to stop crowd gatherings or illegal acts. Tear gas is basically suspended particulates. Most of the suspended particulates will be carried away in the air after tear gas is dispersed.  Even if a trace amount of the particulates remain, the effect will be very limited. People affected by tear gas would be able to recover in a short period of time by leaving the area affected by tear gas, thoroughly washing with plenty of water and soap, and changing contaminated clothes.
 
     The Police will take into account the safety and interests of people affected as far as possible when using tear gas. Before undertaking operations, the Police will, as far as they can, maintain close contact with the management offices of buildings, commercial tenants ,elderly homes etc, nearby through different channels to remind them of the actions that may be taken in relation to demonstrations, so that they can make corresponding arrangements.  During the operations, the Police will also make use of the social media and press releases to appeal to residents in the vicinity to pay attention to the situation, and close windows and stay in a safe indoor place if necessary.

Ends/Wednesday, November 20, 2019
Issued at HKT 15:25

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